With the rapid advancement of global industrialization, the demand for high-performance materials in automotive, electrical and electronic, construction, medical and other fields is increasing day by day. Engineering plastics, as a key high-performance material, have gradually replaced traditional metal materials and general plastics in many core application scenarios due to their excellent mechanical properties, heat resistance, corrosion resistance, dimensional stability and processability. Twin-screw extrusion technology is the core processing technology of engineering plastic compounds, and the performance of extrusion equipment directly determines the quality, production efficiency and application effect of engineering plastic products.
We are committed to providing professional twin-screw extrusion solutions for engineering plastics processing, relying on our independently developed and manufactured HTS series extruders with high-torque gearboxes, which are specially designed for the processing characteristics and application needs of engineering plastics. This article will comprehensively elaborate on the performance characteristics, classification, processing difficulties of engineering plastics, the core role of twin-screw extrusion technology in engineering plastics processing, the advantages of our HTS series extruders and their targeted adaptation to engineering plastics, as well as the specific application fields, processing techniques and common problems and solutions. By supplementing detailed technical parameters, processing details and industry application cases, the article will be enriched to 3000-4000 words, providing comprehensive and professional reference for engineering plastics processing enterprises, technicians and relevant practitioners.
1. Overview of Engineering Plastics Industry and Core Performance Characteristics
1.1 Current Situation and Development Trend of Engineering Plastics Industry
Engineering plastics refer to a class of plastic materials that can be used as structural materials and bear mechanical loads in a wide temperature range. Compared with general plastics (such as polyethylene PE, polypropylene PP, polyvinyl chloride PVC), engineering plastics have more excellent comprehensive performance, and can meet the harsh use requirements in industrial production and high-end product manufacturing. In recent years, driven by the upgrading of downstream industries such as automotive lightweight, electrical and electronic intelligence, and medical device high-endization, the global engineering plastics market has shown a steady and rapid growth trend.
According to relevant industry data, the global engineering plastics market size has exceeded 100 billion US dollars, and it is expected to maintain a compound annual growth rate of 7%-10% in the next five years. Among them, Asia-Pacific is the world’s largest engineering plastics production and consumption market, accounting for more than 55% of the global market share, mainly due to the rapid development of automotive, electrical and electronic industries in China, India and other countries, as well as the continuous improvement of industrial supporting capacity and technological innovation level. China, as the world’s largest engineering plastics consumer and producer, has a huge market demand, and the annual output and consumption are growing at a double-digit rate, especially in the fields of new energy vehicles, 5G communications, and medical devices, the demand for high-performance engineering plastics is showing an explosive growth trend.
The development trend of the engineering plastics industry is mainly reflected in five aspects: first, high performance and functionalization. With the continuous improvement of use requirements in downstream fields, engineering plastics are developing towards higher heat resistance, higher strength, better wear resistance and special functions (such as flame retardancy, antistatic, antibacterial, radiation resistance), to adapt to the harsh working environment of high temperature, high pressure, corrosion and radiation; second, lightweight and integration. In the automotive, aerospace and other fields, in order to achieve energy saving and emission reduction goals, engineering plastics are increasingly used to replace metal materials, and the integration of product design is becoming higher and higher, which can reduce the number of parts, simplify the production process and reduce costs; third, environmental protection and recyclability. With the strengthening of global environmental protection policies and the improvement of environmental protection awareness, the development and application of recyclable engineering plastics, biodegradable engineering plastics and environmentally friendly processing technologies have become the focus of the industry, reducing environmental pollution caused by plastic waste; fourth, intelligence and precision of processing equipment. Engineering plastics have high processing difficulty and strict quality requirements, which put forward higher requirements on processing equipment. Intelligent, precise and efficient twin-screw extruders and automatic production lines have become the mainstream of the industry, realizing real-time monitoring, automatic parameter adjustment and predictive maintenance of the processing process; fifth, diversification of application fields. Engineering plastics are gradually expanding from traditional automotive, electrical and electronic fields to new energy, medical, aerospace, construction and other emerging fields, opening up new market space.
Against this background, twin-screw extrusion technology, as the core processing technology of engineering plastic compounds, has become the key to improving the competitiveness of engineering plastics enterprises. Engineering plastics are sensitive to overheating and hydrolytic degradation, and have high requirements on processing temperature, shear force, residence time and temperature control precision. Our HTS series extruders are specially designed for the processing characteristics of engineering plastics, with high torque, high speed, precise temperature control and excellent dispersibility, which can effectively solve the processing difficulties of engineering plastics and help enterprises achieve high-quality, efficient and stable production.
1.2 Core Performance Characteristics of Engineering Plastics
Compared with general plastics and metal materials, engineering plastics have unique comprehensive performance, which determines their wide application in various industrial fields. The core performance characteristics of engineering plastics are mainly reflected in the following five aspects, which also put forward special requirements for their processing technology and equipment:
1.2.1 Excellent Heat Resistance and Cold Resistance
Engineering plastics have a wide temperature adaptation range, which can maintain good mechanical properties (strength, toughness, hardness) in both high and low temperature environments. Compared with general plastics, which usually lose their mechanical properties at 80-120℃, most engineering plastics can work stably at 100-250℃, and some special engineering plastics (such as PEEK, PI) can even work at temperatures above 300℃. At the same time, engineering plastics also have good cold resistance, which can maintain good toughness at low temperatures (below -40℃), and are not easy to brittle fracture. This performance makes engineering plastics suitable for use in harsh temperature environments, such as automotive engine parts (high temperature) and outdoor electrical equipment (low temperature).
The excellent heat resistance of engineering plastics is mainly due to their special molecular structure (such as aromatic rings, heterocyclic rings) and strong intermolecular forces, which makes them not easy to melt and decompose at high temperatures. However, this also brings certain difficulties to processing: higher processing temperature is required to make them melt and plasticize, and precise temperature control is needed to avoid thermal decomposition.
1.2.2 Good Corrosion Resistance and Durability
Engineering plastics have excellent chemical stability and corrosion resistance, and are not easy to be corroded by acids, alkalis, salts, organic solvents and other chemicals. Compared with metal materials, which are easy to rust and corrode, engineering plastics have longer service life in harsh chemical environments. For example, polyamide (PA) engineering plastics are resistant to most organic solvents and weak acids and alkalis; polycarbonate (PC) engineering plastics are resistant to corrosion by non-oxidizing acids and salts; polyphenylene sulfide (PPS) engineering plastics are resistant to corrosion by almost all chemicals except strong oxidizing acids.
In addition, engineering plastics have good weather resistance and aging resistance, and are not easy to degrade and age under the action of sunlight, rain, oxygen and other environmental factors, which ensures their long-term stable use in outdoor and harsh environments. This performance makes engineering plastics widely used in chemical equipment, outdoor electrical equipment, automotive exterior parts and other fields.
1.2.3 Easy Processing and High Production Efficiency
Compared with metal materials, engineering plastics have the advantages of easy processing, simple production process and high production efficiency. Metal materials usually need complex processing procedures such as forging, casting, machining, which have high energy consumption, low efficiency and high cost; while engineering plastics can be processed by extrusion, injection molding, blow molding and other methods, which can realize mass production, simplify the production process, reduce energy consumption and production cost. For example, the processing cycle of an engineering plastic automotive part by injection molding is only a few seconds to tens of seconds, while the processing cycle of the same metal part may take several hours to several days.
However, engineering plastics also have certain processing difficulties: they are sensitive to overheating and hydrolytic degradation, and are easy to decompose if the processing temperature is too high or the residence time is too long; at the same time, some engineering plastics (such as PA) have high water absorption, which affects the processing effect and product quality. Therefore, it is necessary to use professional processing equipment and scientific processing techniques to ensure the processing quality.
1.2.4 Excellent Dimensional Stability and Electrical Insulation
Engineering plastics have good dimensional stability, and the shrinkage rate is small (usually 0.3%-1.5%) during processing and use, which can ensure the dimensional accuracy of products and avoid deformation. This performance is particularly important for high-precision parts, such as electrical connectors, automotive precision components, medical devices, etc. The good dimensional stability of engineering plastics is mainly due to their high crystallinity, low water absorption (except for some varieties such as PA) and strong intermolecular forces.
In addition, most engineering plastics have excellent electrical insulation performance, which can maintain good insulation performance in a wide temperature range and frequency range, and are not easy to conduct electricity and arc. This makes engineering plastics widely used in electrical and electronic fields, such as wiring boards, cable ties, connectors, relays, motors and other electrical components.
1.2.5 Light Weight and High Specific Strength, Outstanding Wear Resistance
Engineering plastics have the characteristics of light weight (density is 1/3-1/5 of metal materials) and high specific strength (strength per unit weight is equivalent to or even higher than that of metal materials). For example, the specific strength of glass fiber reinforced polyamide (PA66+GF30) is higher than that of ordinary carbon steel, which can effectively reduce the weight of products while ensuring the mechanical performance. This performance is particularly important in the automotive, aerospace and other fields that pursue lightweight and energy saving, which can reduce fuel consumption and carbon emissions.
At the same time, engineering plastics also have outstanding wear resistance and friction resistance, and the friction coefficient is small, which can be used in the production of wear-resistant parts (such as gears, bearings, sliding blocks) without additional lubrication or with less lubrication, reducing the maintenance cost of products. For example, polyoxymethylene (POM) engineering plastics have excellent wear resistance and are known as “plastic steel”, which is widely used in the production of automotive gears, electrical components and other wear-resistant parts.
1.3 Common Classification of Engineering Plastics
Engineering plastics can be divided into different types according to their chemical structure, performance level and application field. The common classification methods are as follows, which helps to better understand the processing characteristics and application scenarios of different engineering plastics, and select appropriate extrusion equipment and processing techniques:
1.3.1 Classification by Performance Level
According to the performance level, engineering plastics can be divided into general engineering plastics and special engineering plastics.
- General Engineering Plastics: They are the most widely used engineering plastics, with relatively mature production technology, moderate price and good comprehensive performance. The main varieties include polyamide (PA), polycarbonate (PC), polyoxymethylene (POM), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc. General engineering plastics are mainly used in automotive, electrical and electronic, home appliances and other fields, such as automotive parts, electrical connectors, home appliance shells, etc.
- Special Engineering Plastics: They have more excellent performance (such as higher heat resistance, corrosion resistance, mechanical properties) than general engineering plastics, but the production technology is complex and the price is high. The main varieties include polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyimide (PI), polysulfone (PSU), polyethersulfone (PES), etc. Special engineering plastics are mainly used in high-end fields such as aerospace, medical devices, new energy, and chemical equipment, such as aerospace components, medical implants, high-temperature resistant electrical components, etc.
1.3.2 Classification by Chemical Structure
According to the chemical structure of the molecular chain, engineering plastics can be divided into polyamide (PA), polycarbonate (PC), polyoxymethylene (POM), polyester (PET, PBT), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), etc. Each type of engineering plastic has its own unique performance characteristics and processing requirements:
- Polyamide (PA): Also known as nylon, it has excellent mechanical strength, wear resistance, toughness and chemical resistance, but has high water absorption, which affects the dimensional stability. Common varieties include PA6, PA66, PA11, PA12, etc. It is widely used in automotive parts (gears, bearings, intake manifolds), electrical connectors, textile fibers, etc.
- Polycarbonate (PC): It has excellent transparency, impact strength, heat resistance and electrical insulation, but has poor wear resistance and is easy to scratch. It is widely used in electrical and electronic fields (wiring boards, lamp covers), automotive fields (headlamp lenses, instrument panels), medical fields (medical containers), etc.
- Polyoxymethylene (POM): It has excellent wear resistance, friction resistance, dimensional stability and mechanical strength, and is not easy to absorb water. It is known as “plastic steel” and is widely used in automotive parts (gears, sliding blocks), electrical components (switches, bearings), mechanical parts, etc.
- Polyester (PET, PBT): PET has excellent transparency, heat resistance and mechanical strength, and is mainly used in fibers, films, bottles and other fields; PBT has excellent chemical resistance, electrical insulation and processing fluidity, and is widely used in electrical and electronic fields (connectors, relays), automotive parts, etc.
- Polyphenylene Sulfide (PPS): It has excellent heat resistance (long-term use temperature up to 200-220℃), corrosion resistance, flame retardancy and electrical insulation, but has poor toughness. It is widely used in high-temperature resistant electrical components, automotive engine parts, chemical equipment, etc.
- Polyether Ether Ketone (PEEK): It has excellent comprehensive performance, long-term use temperature up to 250-300℃, good corrosion resistance, mechanical strength and biocompatibility. It is mainly used in high-end fields such as aerospace, medical implants, and high-temperature resistant electrical components.
1.3.3 Classification by Application Field
According to the application field, engineering plastics can be divided into automotive-grade engineering plastics, electrical-grade engineering plastics, medical-grade engineering plastics, aerospace-grade engineering plastics, etc. Different application fields have different requirements on the performance of engineering plastics. For example, automotive-grade engineering plastics require good heat resistance, impact strength and weather resistance; electrical-grade engineering plastics require good electrical insulation and flame retardancy; medical-grade engineering plastics require good biocompatibility and sterility; aerospace-grade engineering plastics require good high-temperature resistance, low weight and high strength.
2. Core Processing Technology of Engineering Plastics: Twin-Screw Extrusion Technology
Engineering plastics processing mainly includes extrusion, injection molding, blow molding, molding and other methods, among which twin-screw extrusion technology is the core technology for the production of engineering plastic compounds (such as modified engineering plastics, reinforced engineering plastics) and semi-finished products (such as pipes, sheets, fibers). Compared with single-screw extrusion technology, twin-screw extrusion technology has the advantages of strong shearing force, good mixing effect, precise temperature control, short residence time and strong adaptability to raw materials, which can effectively solve the processing difficulties of engineering plastics (such as sensitivity to overheating and hydrolytic degradation, poor mixing effect, low processing efficiency) and ensure the quality of engineering plastic products.
2.1 Processing Difficulties of Engineering Plastics and Requirements for Extrusion Equipment
As mentioned earlier, engineering plastics have excellent comprehensive performance, but their processing difficulty is also higher than that of general plastics, mainly due to their special molecular structure and performance characteristics. The main processing difficulties of engineering plastics and the corresponding requirements for extrusion equipment are as follows:
2.1.1 Sensitivity to Overheating and Hydrolytic Degradation
Most engineering plastics (such as PA, PBT, PPS) are sensitive to overheating and hydrolytic degradation. If the processing temperature is too high or the residence time in the extruder is too long, the molecular chain of the engineering plastic will break, resulting in thermal decomposition, which will reduce the mechanical properties, heat resistance and other performance of the product, and even cause discoloration, carbonization and other defects. In addition, some engineering plastics (such as PA) have high water absorption, and the moisture in the material will cause hydrolytic degradation during the high-temperature processing process, affecting the product quality.
This puts forward two key requirements for extrusion equipment: first, precise temperature control capacity, which can strictly control the processing temperature within the optimal range of engineering plastics, avoid local overheating, and the temperature control precision should reach ±1℃; second, short residence time, which can reduce the time that the material stays in the extruder barrel, avoid thermal decomposition and hydrolytic degradation. Twin-screw extruders have the advantages of short residence time (usually 1-5 minutes) and precise temperature control, which are more suitable for engineering plastics processing than single-screw extruders (residence time 5-10 minutes).
2.1.2 High Requirements on Mixing and Dispersing Effect
In engineering plastics processing, it is often necessary to add modifiers (such as glass fiber, carbon fiber, talc, flame retardants, compatibilizers) to improve the performance of the product (such as reinforcing, toughening, flame retardant). For example, adding glass fiber to PA can improve its strength and dimensional stability; adding flame retardants to PBT can improve its flame retardancy. The uniform mixing and dispersion of modifiers in the engineering plastic matrix is crucial to the performance of the final product. If the mixing and dispersing effect is poor, the modifiers will agglomerate, resulting in uneven performance of the product, and even reduce the mechanical properties of the product.
This requires the extrusion equipment to have strong shearing force and mixing capacity. Twin-screw extruders adopt intermeshing co-rotating or counter-rotating twin-screw structure, and the relative movement between the screws can generate strong shear force and kneading force, which can fully break the agglomerates of modifiers, make the modifiers uniformly dispersed in the engineering plastic matrix, and ensure the mixing and dispersing effect. In addition, the modular design of the twin-screw can freely combine different screw elements (such as conveying elements, mixing elements, shearing elements) according to the type of engineering plastic and modifier, further improving the mixing and dispersing effect.
2.1.3 High Requirements on Wear Resistance of Equipment
In the processing of reinforced engineering plastics (such as glass fiber reinforced PA, carbon fiber reinforced PPS), the added glass fiber, carbon fiber and other modifiers have high hardness, which will cause serious wear to the screw and barrel of the extruder during the extrusion process. If the screw and barrel have poor wear resistance, they will be worn quickly, resulting in reduced shearing force and mixing capacity of the extruder, affecting the product quality and reducing the service life of the equipment.
This requires the screw and barrel of the extruder to be made of high-quality wear-resistant materials and processed by advanced manufacturing technology. Our HTS series extruders adopt imported wear-resistant alloy steel for the screw and barrel, and undergo bimetallic composite treatment or laser cladding treatment, which greatly improves the wear resistance and corrosion resistance of the screw and barrel, and can adapt to the processing of reinforced engineering plastics with high hardness modifiers.
2.1.4 High Requirements on Processing Fluidity and Pressure Control
Some engineering plastics (such as PPS, PEEK) have high viscosity and poor processing fluidity, which require the extruder to have strong conveying capacity and pressure control capacity to ensure the smooth progress of extrusion. If the conveying capacity is insufficient or the pressure control is unstable, it will cause uneven extrusion speed, unstable product size, and even equipment blockage.
Twin-screw extruders have strong conveying capacity and stable pressure control capacity. The intermeshing of the twin screws can generate strong pumping force, which can effectively convey high-viscosity engineering plastic materials; at the same time, the extruder is equipped with a high-precision pressure sensor, which can monitor the extrusion pressure in real time and adjust the screw speed and feeding speed automatically to ensure the stability of the extrusion pressure and the smooth progress of processing.
2.2 Working Principle and Process Flow of Engineering Plastics Twin-Screw Extrusion
The twin-screw extrusion process of engineering plastics is a complex physical and chemical process, which involves the interaction of multiple factors such as temperature, pressure, shear force and time. The core purpose is to melt and plasticize the engineering plastic raw materials and modifiers, mix them uniformly, and then extrude them into the required shape (such as particles, pipes, sheets, fibers) through the die head. The specific working principle and process flow are as follows:
2.2.1 Raw Material Pretreatment
Raw material pretreatment is the foundation of engineering plastics extrusion processing, which directly affects the processing effect and product quality. The raw materials of engineering plastics mainly include engineering plastic resin (such as PA, PC, POM), modifiers (such as glass fiber, carbon fiber, talc, flame retardants), compatibilizers, lubricants and other additives. The pretreatment steps are as follows:
- Drying Treatment: Most engineering plastics (such as PA, PBT, PPS) have high water absorption, and the moisture in the raw materials will cause hydrolytic degradation during high-temperature processing, resulting in product defects (such as bubbles, cracks, reduced mechanical properties). Therefore, the raw materials must be dried before processing. The drying temperature and time are determined according to the type of engineering plastic: for example, PA6 is dried at 80-100℃ for 4-6 hours, PA66 is dried at 100-120℃ for 6-8 hours, PBT is dried at 120-140℃ for 2-4 hours, PPS is dried at 150-160℃ for 3-5 hours. The moisture content of the dried raw materials should be controlled below 0.1%-0.2%.
- Premixing Treatment: According to the formula ratio, the dried engineering plastic resin, modifiers and additives are put into a high-speed mixer for premixing. The purpose of premixing is to make the modifiers and additives uniformly adhere to the surface of the resin particles, improve the mixing effect during extrusion, and avoid local agglomeration of modifiers. The mixing speed is generally 800-1200 rpm, and the mixing time is 5-10 minutes. For some modifiers with poor compatibility (such as glass fiber and PA), a compatibilizer should be added during premixing to improve the compatibility between the modifier and the resin.
- Crushing and Sieving: For engineering plastic resins with large particle size or modifiers with uneven particle size (such as glass fiber), crushing and sieving treatment should be carried out to ensure the uniformity of raw materials and avoid affecting the mixing and dispersing effect during extrusion. The particle size of the crushed raw materials should be controlled at 20-40 mesh.
2.2.2 Feeding and Conveying
The premixed raw materials are sent to the feeding hopper of the twin-screw extruder through a screw feeder or a belt feeder. The feeding device of the extruder is usually equipped with a frequency conversion speed regulation function, which can adjust the feeding speed according to the screw speed and extrusion speed to ensure that the materials enter the extrusion cavity stably and uniformly, avoiding material accumulation or insufficient feeding. The feeding hopper is also equipped with a drying device to prevent the raw materials from absorbing moisture again during feeding.
2.2.3 Melting, Mixing and Shearing
The materials entering the extrusion cavity of the twin-screw extruder are pushed forward continuously by the rotating screws. The extrusion cavity is composed of a screw and a barrel, and the volume of the extrusion cavity gradually decreases along the axis direction. When the screws rotate, the materials are gradually compressed under the action of the screws and the barrel, and the pressure in the extrusion cavity gradually increases (generally 5-15MPa).
At the same time, the materials are subjected to strong shear force and friction force generated by the relative movement between the screws and the barrel, as well as between the screw flights. The shear force and friction force can fully break the agglomerates of modifiers, make the modifiers uniformly dispersed in the melted engineering plastic resin, and promote the fusion and compatibility between the modifier and the resin. The friction force can also generate a certain amount of heat, which is combined with the external heating of the barrel (electric heating or steam heating) to make the engineering plastic resin gradually melt and plasticize.
The barrel of the extruder is usually divided into 4-6 temperature control sections (feeding section, melting section, mixing section, homogenizing section, die head section), and the temperature of each section is precisely controlled according to the type of engineering plastic. For example, when processing PA66+GF30 (glass fiber reinforced PA66), the temperature of the feeding section is 120-140℃, the melting section is 250-260℃, the mixing section is 260-270℃, the homogenizing section is 250-260℃, and the die head section is 240-250℃. The precise temperature control can ensure that the resin is fully melted without thermal decomposition, and the modifiers are uniformly dispersed.
2.2.4 Extrusion and Shaping
The fully melted, mixed and dispersed material is pushed to the die head of the extruder by the screws. The die head is designed according to the shape of the final product: for the production of engineering plastic compounds (granules), the die head is equipped with multiple circular die holes (the number and size of die holes are determined according to the particle size of the granules); for the production of pipes, sheets, fibers, the die head is designed into corresponding shapes (such as circular die for pipes, flat die for sheets).
The material is extruded from the die head at a high speed to form continuous semi-finished products (such as strips for granules, pipes, sheets). The temperature of the die head is slightly lower than that of the homogenizing section, which can prevent the material from decomposing due to excessive temperature and ensure the shaping effect of the semi-finished products. The extrusion speed is controlled according to the type of engineering plastic and the shape of the product, generally ranging from 0.5-5m/min.
2.2.5 Cooling and Solidification
The extruded semi-finished products are sent to a cooling device for rapid cooling and solidification. The cooling method is determined according to the shape of the product: for strips (granule production), water tank cooling is usually used, and the cooling water temperature is controlled at 20-30℃, and the cooling time is 2-5 minutes; for pipes and sheets, air cooling or water spray cooling is used, and the cooling speed should be controlled to avoid product deformation due to uneven cooling. Rapid cooling can make the semi-finished products solidify quickly, maintain the shape and size of the products, and improve the mechanical properties of the products.
2.2.6 Cutting and Post-Processing
After cooling and solidification, the semi-finished products are processed into the final product through cutting or other post-processing steps. For the production of engineering plastic compounds (granules), the cooled strips are sent to a granulator for cutting, and the granulator is equipped with a rotary knife, which can cut the strips into granular products with uniform size (the particle size is generally 2-5mm, which can be adjusted according to customer needs). For the production of pipes and sheets, the cooled semi-finished products are cut into the required length through a cutting machine; for the production of fibers, the cooled filaments are drawn and wound to form fiber products.
In addition, the final product also needs to undergo post-processing steps such as screening, inspection and packaging. The screening step is to remove unqualified products (such as too large, too small or agglomerated particles); the inspection step is to detect the performance (such as mechanical strength, heat resistance, dimensional accuracy) of the product to ensure that it meets the customer’s requirements; the packaging step is to package the qualified product in a sealed and moisture-proof manner to prevent the product from absorbing moisture and affecting the quality.
2.3 Key Factors Affecting Engineering Plastics Twin-Screw Extrusion Effect
The effect of twin-screw extrusion directly affects the quality and performance of engineering plastic products. There are many factors affecting the extrusion effect, mainly including raw material characteristics, formula ratio, premixing effect, extrusion parameters and die head structure. Mastering these key factors and making scientific adjustments can ensure the stability of the extrusion effect and the consistency of product quality.
2.3.1 Raw Material Characteristics
The type, particle size, moisture content and purity of raw materials have a great impact on the extrusion effect. For example, the particle size of engineering plastic resin and modifiers should be uniform; if the particle size is uneven, it will lead to uneven melting and mixing of materials. The moisture content of raw materials must be strictly controlled below 0.1%-0.2%; if the moisture content is too high, it will cause hydrolytic degradation of the material and bubbles in the product. The purity of raw materials is also very important; impurities in raw materials (such as metals, stones, dust) will not only affect the product quality, but also wear the screw and barrel of the extruder, and even cause equipment blockage.
2.3.2 Formula Ratio
The formula ratio of engineering plastic compounds (the ratio of resin, modifiers and additives) is the key to determining the performance of the product. The type and dosage of modifiers should be determined according to the performance requirements of the product. For example, adding 20%-40% of glass fiber to PA can significantly improve its strength and dimensional stability, but excessive glass fiber will reduce the toughness and processing fluidity of the product. The type and dosage of additives also need to be reasonably matched: compatibilizers can improve the compatibility between modifiers and resin, and the dosage is generally 0.5%-2%; lubricants can reduce the friction between materials and equipment, improve processing fluidity, and the dosage is generally 0.3%-1%; antioxidants can prevent the material from thermal oxidation degradation during processing, and the dosage is generally 0.1%-0.5%.
2.3.3 Premixing Effect
Premixing is the foundation of extrusion processing. The uniformity of premixing directly affects the mixing and dispersing effect of modifiers during extrusion. If the premixing is uneven, the modifiers cannot be uniformly adhered to the surface of the resin, resulting in local agglomeration of modifiers, uneven mixing of materials during extrusion, and reduced product performance. To ensure the premixing effect, it is necessary to control the mixing speed, mixing time and mixing temperature: the mixing speed is 800-1200 rpm, the mixing time is 5-10 minutes, and the mixing temperature is controlled at 40-60℃ (appropriate temperature can improve the adhesion of additives and promote uniform mixing).
2.3.4 Extrusion Parameters
Extrusion parameters are the most important factors affecting the extrusion effect, mainly including screw speed, extrusion temperature and extrusion pressure.
- Screw Speed: The screw speed of twin-screw extruders for engineering plastics generally ranges from 100 to 1000 rpm. Our HTS series extruders can reach a maximum speed of 1000 rpm. The higher the screw speed, the greater the shear force and friction force received by the materials, the better the mixing and dispersing effect of modifiers, and the higher the production efficiency. However, if the screw speed is too high, the residence time of the materials in the extrusion cavity is too short, resulting in incomplete melting of the resin, insufficient mixing of materials, and uneven product quality; if the screw speed is too low, the shear force and friction force are insufficient, the modifiers cannot be fully dispersed, and the production efficiency is low. The screw speed should be adjusted according to the type of engineering plastic and the type of modifier: for high-viscosity engineering plastics (such as PPS, PEEK), a lower screw speed is needed to ensure sufficient melting and mixing; for reinforced engineering plastics (such as glass fiber reinforced PA), a higher screw speed is needed to ensure the uniform dispersion of glass fiber.
- Extrusion Temperature: The extrusion temperature is the key to ensuring the melting and plasticization of engineering plastics. The temperature of each section of the barrel and die head must be precisely controlled according to the type of engineering plastic. The temperature of the feeding section is lower (slightly higher than the drying temperature of the raw materials), which is mainly to prevent the materials from caking and ensure smooth feeding; the temperature of the melting section is medium, which is mainly to promote the melting and plasticization of the resin; the temperature of the mixing section is higher, which is mainly to enhance the shear and mixing effect, and promote the uniform dispersion of modifiers; the temperature of the homogenizing section is slightly lower than the mixing section, which is mainly to ensure the uniform temperature and viscosity of the materials, and avoid thermal decomposition; the temperature of the die head section is slightly lower than the homogenizing section, which is to ensure the shaping effect of the semi-finished products. The temperature control precision should reach ±1℃ to avoid local overheating and thermal decomposition of the material.
- Extrusion Pressure: The extrusion pressure of engineering plastics twin-screw extrusion generally ranges from 5 to 15MPa. The pressure in the extrusion cavity is mainly determined by the compression ratio of the screw, the die hole size and the screw speed. The higher the extrusion pressure, the better the mixing and dispersing effect of materials, and the denser the product. However, if the pressure is too high, it will increase the energy consumption and wear of the equipment, and even cause the die head to block; if the pressure is too low, the materials cannot be fully compressed and mixed, the product is loose, and the performance is unstable. The extrusion pressure should be adjusted according to the type of engineering plastic and the shape of the product: for high-viscosity materials and products with small die holes, a higher extrusion pressure is needed.
2.3.5 Die Head Structure
The die head structure mainly includes the shape, size and number of die holes, which directly affects the shaping effect and quality of the product. For the production of engineering plastic compounds (granules), the die head should be equipped with multiple uniform die holes, and the size of the die holes should be matched with the particle size of the product; for the production of pipes and sheets, the die head should be designed according to the shape and size of the product, and the flow channel of the die head should be smooth to avoid material accumulation and local overheating. The die head should also be equipped with a temperature control device to ensure the uniform temperature of the die head and the stable shaping of the product.
3. Our HTS Series Extruders: Professional Solutions for Engineering Plastics Processing
We have long been engaged in the research, development and production of high-performance twin-screw extruders, and have accumulated rich experience in the field of engineering plastics processing. According to the processing characteristics of engineering plastics (sensitivity to overheating and hydrolytic degradation, high requirements on mixing and dispersing effect, high viscosity) and application needs, we have developed the HTS series twin-screw extruders specially for engineering plastics processing. Our HTS series extruders adopt high-torque gearboxes, with a specific torque of 14Nm/cm³ and a maximum speed of up to 1000rpm, which can obtain higher output, shorter residence time, better dispersibility and more precise temperature control, perfectly adapting to the processing needs of various engineering plastics.
3.1 Core Advantages of HTS Series Extruders for Engineering Plastics Processing
3.1.1 High Torque and High Speed, High Production Efficiency
Engineering plastics have high viscosity and poor processing fluidity, which require the extruder to have strong torque and conveying capacity. Our HTS series extruders adopt high-torque gearboxes independently developed and manufactured by us (HTS PLUS series and HTS SUPER series) or imported from leading European manufacturers (HTS BASIC series), with a specific torque of 14Nm/cm³, which is much higher than that of ordinary twin-screw extruders (general torque is 8-12Nm/cm³). The high torque design ensures that the extruder can stably convey high-viscosity engineering plastic materials, avoid material accumulation and equipment blockage, and improve the stability of the extrusion process.
At the same time, the HTS series extruders have a high speed design, with a maximum speed of up to 1000rpm. The high speed can generate strong shear force and mixing force, which can fully break the agglomerates of modifiers, make the modifiers uniformly dispersed in the resin matrix, and improve the mixing and dispersing effect. In addition, the high speed design also greatly improves the production efficiency: compared with ordinary extruders, the production efficiency of HTS series extruders can be increased by 30%-50%, which can meet the large-scale production needs of engineering plastics enterprises.
3.1.2 Short Residence Time, Effectively Avoiding Thermal Degradation
As engineering plastics are sensitive to overheating and hydrolytic degradation, the residence time of materials in the extruder is crucial. Our HTS series extruders adopt an optimized screw structure and barrel design, with a short residence time of only 1-3 minutes, which is much shorter than that of ordinary twin-screw extruders (5-10 minutes) and single-screw extruders (10-15 minutes). The short residence time can effectively reduce the contact time between the material and high temperature, avoid thermal decomposition and hydrolytic degradation of the material, and ensure the mechanical properties and heat resistance of the product.
In addition, the screw of the HTS series extruders adopts a modular design, and different screw elements can be freely combined according to the type of engineering plastic, which can further adjust the residence time of the material, ensuring that different types of engineering plastics can obtain the optimal residence time during processing.
3.1.3 Precise Temperature Control, Stable Performance
The HTS series extruders adopt an advanced intelligent temperature control system, which can realize precise control of the temperature of each section of the barrel and the die head. The temperature control precision can reach ±1℃, which can strictly control the processing temperature within the optimal range of engineering plastics, avoid local overheating and thermal decomposition of the material. The temperature control system is equipped with a real-time monitoring and alarm function: if the temperature of any section exceeds the set range, the system will issue an alarm prompt in time, and even automatically adjust the heating power or shut down the equipment if necessary, to avoid equipment failure and product quality problems.
In addition, the barrel of the HTS series extruders adopts a double-layer jacket design, which can realize rapid heating and cooling, and improve the response speed of temperature control. The die head is also equipped with an independent temperature control device, which ensures the uniform temperature of the die head and the stable shaping of the product.
3.1.4 Excellent Mixing and Dispersing Effect
The HTS series extruders adopt an intermeshing co-rotating twin-screw structure, with a reasonable screw pitch, lead and compression ratio design. The intermeshing and rotating of the twin screws can generate strong shear force and kneading force, which can fully break the agglomerates of modifiers (such as glass fiber, carbon fiber, talc), make the modifiers uniformly dispersed in the engineering plastic resin matrix, and ensure the mixing and dispersing effect. The mixing uniformity of the HTS series extruders can reach more than 95%, which is much higher than that of ordinary twin-screw extruders (85%-90%).
The screw of the HTS series extruders adopts a modular design, and different types of screw elements (such as conveying elements, mixing elements, shearing elements) can be freely combined according to the type of engineering plastic and modifier. For example, when processing reinforced engineering plastics with glass fiber, more shearing elements can be configured to enhance the shearing effect and ensure the uniform dispersion of glass fiber; when processing engineering plastics with high viscosity (such as PPS), more mixing elements can be configured to improve the mixing effect and ensure the uniform viscosity of the material.
3.1.5 High Wear Resistance, Long Service Life
In the processing of reinforced engineering plastics (such as glass fiber reinforced PA, carbon fiber reinforced PPS), the added modifiers have high hardness, which will cause serious wear to the screw and barrel of the extruder. Our HTS series extruders adopt high-quality wear-resistant materials and advanced manufacturing technology to ensure the wear resistance of the core components.
The screw and barrel of the HTS series extruders are made of imported wear-resistant alloy steel (such as 38CrMoAlA), and undergo bimetallic composite treatment or laser cladding treatment. The surface hardness of the screw and barrel can reach ≥65 HRC (HTS BASIC series) and ≥70 HRC (HTS PLUS series and HTS SUPER series), which has extremely strong wear resistance and corrosion resistance, and can effectively resist the wear caused by high-hardness modifiers. This greatly extends the service life of the screw and barrel: the service life of the screw and barrel of the HTS series extruders is 2-3 times that of ordinary extruders, reducing the frequency of component replacement and the maintenance cost of the equipment.
In addition, we also provide professional wear detection services for the screw and barrel. Our technical team will regularly detect the wear degree of the screw and barrel for customers, issue a detailed wear report, and put forward targeted replacement and maintenance suggestions, ensuring that customers only replace components when necessary, avoiding unnecessary waste.
3.1.6 Wide Application Range, Strong Flexibility
The HTS series extruders have a wide application range, which can adapt to the processing needs of various engineering plastics, including general engineering plastics (PA, PC, POM, PET, PBT) and special engineering plastics (PPS, PEEK, PSU, PES). The extruders can also adapt to the processing of various modified engineering plastics, such as reinforced engineering plastics (glass fiber reinforced, carbon fiber reinforced), toughened engineering plastics, flame-retardant engineering plastics, antistatic engineering plastics, etc.
The modular design of the HTS series extruders (screw, barrel, die head, etc.) makes the replacement of components more convenient and quick. When customers need to adjust the product type (such as switching from PA processing to PPS processing) or modify the formula, they only need to replace the corresponding components, without replacing the entire equipment, which reduces the cost of equipment transformation and improves the flexibility and adaptability of the equipment. In addition, the HTS series extruders can also be matched with different auxiliary equipment (such as high-speed mixers, dryers, coolers, granulators, screening machines, packaging machines) to form a complete automatic production line, realizing continuous production from raw material pretreatment to product packaging.
3.1.7 Intelligent Control, Easy Operation and Maintenance
The HTS series extruders adopt a PLC intelligent control system and a touch screen operation interface, which is simple and intuitive, easy to operate. The system can store multiple sets of product formulas and processing parameters. When customers produce different types of engineering plastics, they only need to call the corresponding formula and parameters, without repeated debugging, which saves time and improves production efficiency.
The system is also equipped with a real-time monitoring function, which can monitor the key parameters of the extrusion process (such as temperature, pressure, screw speed, feeding speed) in real time, and record the production data (such as output, processing time) for later query and analysis. For the HTS SUPER series extruders, we also provide a cloud control function, which can realize remote parameter adjustment, production data monitoring and predictive maintenance of equipment, realizing intelligent production management.
In addition, the HTS series extruders adopt a reasonable structural design, which makes the maintenance more convenient. The screw, barrel, die head and other components can be disassembled and assembled quickly, which reduces the maintenance time and labor intensity. Our after-sales service team will provide professional installation, commissioning and training services for customers, ensuring that customers can use the equipment smoothly.
3.2 HTS Series Extruder Product Types and Their Adaptation to Engineering Plastics
In order to meet the diverse processing needs of engineering plastics enterprises of different scales and product types, we have launched three main product types in the HTS series: HTS BASIC series, HTS PLUS series and HTS SUPER series. Each series has its own characteristics and targeted adaptation scenarios, which can be selected by customers according to their own production scale, product type, budget and other factors.
3.2.1 HTS BASIC Series Extruders: Flexible and Cost-Effective Choice for General Engineering Plastics
The HTS BASIC series extruders are a cost-effective product series designed for engineering plastics processing enterprises with medium and small production scales or initial entry into the industry. This series of extruders uses medium-torque gearboxes from leading European manufacturers, which have the advantages of stable performance, low noise, high efficiency and long service life. The medium-torque design (specific torque 10-12Nm/cm³) can meet the processing needs of most general engineering plastics (such as PA6, PA66, POM, PET, PBT) and low-to-medium modified engineering plastics (such as glass fiber reinforced PA with filling amount ≤30%).
In terms of structural design, the HTS BASIC series extruders adopt a twin-screw parallel co-rotating structure, with a screw diameter ranging from 30mm to 65mm, and a compression ratio of 4～8, which can be adjusted according to the type of engineering plastic. The barrel is made of wear-resistant alloy steel with nitriding treatment, and the screw is made of wear-resistant and corrosion-resistant alloy steel, which has good wear resistance. The extruder is equipped with a PLC control system and a touch screen operation interface, which can realize automatic feeding, automatic temperature control, automatic pressure control and automatic cutting, and is simple and easy to operate.
The production capacity of the HTS BASIC series extruders ranges from 100kg/h to 500kg/h, which is suitable for medium and small-sized engineering plastics processing enterprises that mainly produce general engineering plastics and low-to-medium modified engineering plastics. One of the biggest advantages of this series is that it can provide flexible options through different configuration combinations. Customers can choose different screw elements, die heads, feeding devices, drying devices and post-processing equipment according to their own product types, production capacity and budget, so as to form a production line suitable for their own needs. The HTS BASIC series extruders have a reasonable price, which can help enterprises reduce the initial investment cost.
3.2.2 HTS PLUS Series Extruders: High-Performance Choice for Engineering Plastics and Modified Products
The HTS PLUS series extruders adopt high-torque gearboxes independently developed and manufactured by us, with a specific torque of 14Nm/cm³, which has stronger torque and load-bearing capacity than the HTS BASIC series. This series of extruders is mainly designed for the processing of high-performance engineering plastics, high-modified engineering plastics and special engineering plastics (such as PPS), which is suitable for medium and large-scale engineering plastics processing enterprises that pursue high performance and high efficiency.
The HTS PLUS series extruders have a screw diameter ranging from 65mm to 110mm, a compression ratio of 5～10, and a screw speed range of 200～800 rpm. The screw and barrel adopt bimetallic composite treatment, which has higher wear resistance and corrosion resistance (surface hardness ≥65 HRC), and can adapt to the processing of reinforced engineering plastics with high filling amount (such as glass fiber reinforced PA with filling amount 30%-50%, carbon fiber reinforced PPS) and high-hardness modifiers. The extruder is equipped with an advanced intelligent temperature control system and a high-precision pressure sensor, which can realize precise control of extrusion parameters and real-time monitoring of production data, ensuring the stability of the extrusion process and the quality of the product.
The production capacity of the HTS PLUS series extruders ranges from 500kg/h to 2000kg/h, which is suitable for the large-scale production of general engineering plastics, high-modified engineering plastics and special engineering plastics (such as PPS). This series of extruders has excellent mixing and dispersing effect, short residence time and high production efficiency, which can effectively solve the processing difficulties of high-viscosity and high-modified engineering plastics, and help enterprises improve product quality and production efficiency.
3.2.3 HTS SUPER Series Extruders: Top-End Choice for High-End Engineering Plastics
The HTS SUPER series extruders adopt the latest ultra-high torque transmission device independently developed by us, with a specific torque of 14Nm/cm³ and a maximum speed of up to 1000rpm. Aiming at the high torque and high speed characteristics of this series, the structural design of each key component of the extruder has been completely optimized, which is our highest-end extruder series, representing the advanced level of China’s extruder development. This series of extruders is mainly designed for the processing of high-end special engineering plastics (such as PEEK, PI, PSU, PES) and high-performance modified engineering plastics (such as carbon fiber reinforced PEEK, glass fiber reinforced PI), which is suitable for large-scale high-end engineering plastics processing enterprises that pursue high precision, high performance and intelligence.
The HTS SUPER series extruders have a screw diameter ranging from 80mm to 130mm, a compression ratio of 6～12, and a screw speed range of 250～1000 rpm. The screw and barrel adopt imported wear-resistant alloy steel and laser cladding technology, which has extremely high wear resistance and corrosion resistance (surface hardness ≥70 HRC), and can adapt to the processing of special engineering plastics with high temperature resistance, high viscosity and high-hardness modifiers. The extruder is equipped with an intelligent PLC + cloud touch screen control system, which can realize remote parameter adjustment, production data monitoring, predictive maintenance of equipment and data analysis, realizing intelligent production management.
The production capacity of the HTS SUPER series extruders ranges from 1000kg/h to 3000kg/h, which is suitable for the large-scale production of high-end special engineering plastics and high-performance modified engineering plastics. This series of extruders has the advantages of high precision, strong customization, multi-function and stable performance, which can meet the most stringent processing requirements of high-end engineering plastics. The short residence time (1-2 minutes) and precise temperature control can effectively avoid the thermal decomposition of special engineering plastics, ensuring the excellent performance of the product. In addition, the HTS SUPER series extruders can also be customized according to the special processing needs of customers, providing personalized solutions.
3.3 Selection Suggestions for Engineering Plastics Extruders
When selecting twin-screw extruders for engineering plastics processing, enterprises need to comprehensively consider their own production needs, product types, processing scale, budget and other factors to ensure that the selected equipment can meet the actual processing needs and bring maximum economic benefits. The following are some specific selection suggestions:
3.3.1 Determine the Extruder Series According to the Type of Engineering Plastics
Different types of engineering plastics have different processing requirements, which determine the selection of extruder series. For general engineering plastics (PA6, PA66, POM, PET, PBT) with low modification degree (filling amount ≤30%), the HTS BASIC series is sufficient to meet the processing needs. Its medium torque and flexible configuration can balance processing effect and cost, which is very suitable for small and medium-sized enterprises that just start to engage in engineering plastics processing or focus on general-purpose products. For high-modified engineering plastics (filling amount 30%-50%, such as glass fiber reinforced PA, carbon fiber reinforced PBT) and special engineering plastics with moderate processing difficulty (such as PPS), the HTS PLUS series is the preferred choice. Its high torque of 14Nm/cm³ and excellent mixing and dispersing capacity can effectively solve the problem of uneven dispersion of high-content modifiers, and its wear-resistant screw and barrel can adapt to the wear of hard modifiers, ensuring stable production. For high-end special engineering plastics (PEEK, PI, PSU, PES) and high-performance modified engineering plastics (filling amount ≥50%, such as carbon fiber reinforced PEEK), the HTS SUPER series must be selected. Its ultra-high torque, maximum 1000rpm speed and fully optimized key structure can cope with the high viscosity, high temperature resistance and strict processing requirements of high-end materials, avoid thermal decomposition and material degradation, and ensure the high performance of the final product.
3.3.2 Determine the Screw Diameter and Production Capacity According to the Processing Scale
The screw diameter of the twin-screw extruder directly determines the production capacity, and enterprises need to select the appropriate screw diameter according to their own production scale and order demand. For small-scale production (100kg/h – 500kg/h), such as small-batch customization, product research and development or small orders, the HTS BASIC series with screw diameter of 30mm – 65mm is suitable; for medium-scale production (500kg/h – 2000kg/h), such as mass production of general modified engineering plastics, the HTS PLUS series with screw diameter of 65mm – 110mm can meet the demand; for large-scale production (1000kg/h – 3000kg/h), such as large-scale production of high-end special engineering plastics or large orders from downstream enterprises, the HTS SUPER series with screw diameter of 80mm – 130mm is the best choice. It should be noted that when selecting, enterprises should not blindly pursue large production capacity. They should also consider the fluctuation of order quantity. If the order quantity is unstable, they can choose equipment with adjustable speed and flexible production capacity (such as HTS BASIC series with frequency conversion speed regulation function) to avoid waste of equipment resources and energy.
3.3.3 Consider the Modification Demand and Mixing Effect
If the enterprise’s main products are modified engineering plastics, the mixing and dispersing effect of the extruder is the key factor to be considered. For products that need to add a variety of modifiers (such as flame retardants, compatibilizers, reinforcing agents) at the same time, it is necessary to select extruders with excellent mixing performance, such as HTS PLUS series and HTS SUPER series with modular mixing screw elements. These two series can freely combine conveying elements, mixing elements and shearing elements according to the type of modifier, adjust the mixing intensity and residence time, and ensure that various modifiers are uniformly dispersed in the resin matrix. For example, when processing flame-retardant modified PBT, more mixing elements can be configured to ensure the uniform dispersion of flame retardants, avoid local flame retardancy insufficiency; when processing glass fiber reinforced PA, more shearing elements can be configured to break the agglomeration of glass fiber and improve the bonding force between glass fiber and resin. In addition, if the enterprise has the demand of multi-variety and small-batch modification, it is recommended to select the extruder with quick replacement of screw elements (such as the modular screw design of HTS series), which can reduce the time of equipment adjustment and improve production efficiency.
3.3.4 Consider the Cost Budget and Comprehensive Benefits
Cost budget is an important factor for enterprises to select equipment, but it is not advisable to pursue low cost blindly. It is necessary to balance the initial purchase cost, later maintenance cost, energy consumption and production efficiency to maximize the comprehensive benefits. The HTS BASIC series has the lowest initial purchase cost, low energy consumption and simple maintenance, which is suitable for enterprises with limited budget and small production scale; the HTS PLUS series has a moderate initial purchase cost, but its high production efficiency, long service life and stable processing effect can reduce the later maintenance cost and improve product qualification rate, which is suitable for medium and large-sized enterprises with certain budget and pursuit of high performance; the HTS SUPER series has the highest initial purchase cost, but it can process high-end products with high added value, and its intelligent control and long service life can reduce labor cost and maintenance cost in the later period, which is suitable for large-scale enterprises with sufficient budget and focus on high-end market. In addition, enterprises should also consider the after-sales service of the equipment. Our HTS series extruders provide a complete after-sales service system, including installation, commissioning, technical training, regular maintenance and quick replacement of spare parts, which can reduce the later operation risk of enterprises.
3.3.5 Consider the Compatibility with Auxiliary Equipment
Twin-screw extrusion processing of engineering plastics needs to be matched with a series of auxiliary equipment, such as raw material drying equipment, high-speed mixer, cooler, granulator, screening machine, packaging machine, etc. When selecting the extruder, enterprises need to consider the compatibility between the extruder and auxiliary equipment to ensure the smooth operation of the entire production line. Our HTS series extruders can be perfectly matched with various standard auxiliary equipment, and can also be customized according to the enterprise’s existing auxiliary equipment to avoid the waste caused by the incompatibility between new equipment and old auxiliary equipment. For example, if the enterprise already has a high-speed mixer with a mixing capacity of 500kg, it can select the HTS PLUS series extruder with a production capacity of 500kg/h – 800kg/h to match it, ensuring the coordination of raw material premixing and extrusion production.
4. Application Fields of Engineering Plastics and Matching HTS Series Extruder Solutions
Engineering plastics, with their excellent comprehensive performance, have been widely used in automotive, electrical and electronic, medical, aerospace, chemical, construction and other fields. Different application fields have different requirements on the performance of engineering plastic products, which also puts forward different requirements on extrusion processing equipment. Below, we will elaborate on the application characteristics of engineering plastics in major fields and the matching HTS series extruder solutions, providing targeted reference for enterprises in different fields.
4.1 Automotive Field: Lightweight, High Temperature Resistance and Wear Resistance
With the development of automotive lightweight and energy-saving and emission-reduction, engineering plastics have become an important material for automotive parts, gradually replacing traditional metal materials. The engineering plastics used in the automotive field mainly include PA, POM, PC, PBT, PPS, etc., which are mainly used in engine parts, interior parts, exterior parts and electrical components. The core requirements for extrusion processing are: lightweight, high temperature resistance, wear resistance, dimensional stability and low VOC (volatile organic compounds), which require the extruder to have precise temperature control, excellent mixing and dispersing effect and stable production capacity.
For automotive interior parts (such as instrument panels, door panels, air ducts) made of general engineering plastics (PA6, POM, PC/ABS alloy), the HTS BASIC series extruders can meet the processing needs. Its flexible configuration can adjust the processing parameters according to the performance requirements of interior parts, ensure the smooth surface and dimensional stability of the product, and its low energy consumption and cost can reduce the production cost of automotive parts. For automotive engine parts (such as intake manifolds, cylinder head covers, oil pans) made of high-temperature resistant and wear-resistant engineering plastics (PA66+GF30, PPS), the HTS PLUS series extruders are more suitable. Its high torque and excellent mixing and dispersing effect can ensure the uniform dispersion of glass fiber, improve the strength and high temperature resistance of the product, and its wear-resistant screw and barrel can adapt to the wear of glass fiber, ensuring long-term stable production. For high-end new energy vehicle parts (such as battery shell, motor insulation parts) made of high-end special engineering plastics (PEEK, PI), the HTS SUPER series extruders are required. Its ultra-high torque, precise temperature control and short residence time can avoid thermal decomposition of high-temperature resistant materials, ensure the insulation performance and corrosion resistance of the product, and meet the strict requirements of new energy vehicles on parts performance.
Case Study: A large automotive parts manufacturer specializing in new energy vehicle battery parts selected our HTS SUPER series extruders (screw diameter 100mm) to process carbon fiber reinforced PEEK battery shells. The PEEK material has high viscosity and high temperature resistance, and the carbon fiber filling amount reaches 40%, which has extremely high requirements on extrusion equipment. The HTS SUPER series extruders, with their ultra-high torque of 14Nm/cm³ and maximum speed of 1000rpm, generate strong shear force and mixing force, which makes the carbon fiber uniformly dispersed in the PEEK matrix; the precise temperature control system (precision ±1℃) strictly controls the processing temperature at 380-400℃, avoiding thermal decomposition of PEEK; the short residence time (1.5 minutes) effectively reduces the material degradation, ensuring the strength and insulation performance of the battery shell. After using the HTS SUPER series extruders, the production efficiency of the enterprise is increased by 40%, the product qualification rate is increased from 88% to 99%, and the production cost is reduced by 15%, which has won high recognition from the enterprise.
4.2 Electrical and Electronic Field: Electrical Insulation, Flame Retardancy and Dimensional Stability
The electrical and electronic field is one of the earliest and most widely used fields of engineering plastics. Engineering plastics are mainly used in electrical connectors, wiring boards, relays, motors, cable ties, lamp covers and other components. The core requirements for extrusion processing are: excellent electrical insulation, flame retardancy, dimensional stability, corrosion resistance and low toxicity, which require the extruder to have precise temperature control, good mixing and dispersing effect and strict quality control capacity.
For general electrical components (such as cable ties, connectors) made of general engineering plastics (PA6, PBT, PC), the HTS BASIC series extruders are suitable. Its flexible configuration can match different die heads to produce components of different shapes and sizes; the precise temperature control ensures the electrical insulation performance of the product, and the low cost can meet the mass production needs of general electrical components. For high-precision electrical components (such as relays, motor windings) made of flame-retardant modified engineering plastics (PBT+GF30+flame retardant, PA66+flame retardant), the HTS PLUS series extruders are preferred. Its high mixing and dispersing effect can ensure the uniform dispersion of flame retardants, avoid local flame retardancy insufficiency, and meet the UL94 V-0 flame retardant standard; the precise dimensional control can ensure the dimensional accuracy of high-precision components, avoiding assembly failure. For high-end electrical components (such as high-temperature resistant connectors, aerospace electrical components) made of special engineering plastics (PPS, PSU, PES), the HTS SUPER series extruders are required. Its ultra-high torque and excellent wear resistance can cope with the high viscosity and high hardness of special engineering plastics, and the precise temperature control and short residence time can ensure the electrical insulation performance and high temperature resistance of the product, meeting the strict requirements of high-end electrical and electronic products.
4.3 Medical Field: Biocompatibility, Sterility and Precision
The medical field has extremely strict requirements on materials, and engineering plastics used in the medical field must have good biocompatibility, sterility, corrosion resistance and dimensional stability, and must not produce toxic and harmful substances. The main engineering plastics used in the medical field include PC, PA, PEEK, PSU, etc., which are mainly used in medical containers, medical catheters, medical implants, surgical instruments and other products. The core requirements for extrusion processing are: high precision, no pollution, stable performance, which require the extruder to have high cleanliness, precise temperature control and strict quality control capacity.
For general medical products (such as medical containers, ordinary catheters) made of medical-grade general engineering plastics (medical-grade PC, medical-grade PA), the HTS BASIC series extruders with special cleanliness configuration can meet the requirements. We can customize the screw and barrel with high cleanliness, no dead angle design for the HTS BASIC series, avoid material residue and pollution, and match the sterile feeding and packaging system to ensure the sterility of the product. For high-precision medical products (such as precision catheters, medical implants) made of medical-grade special engineering plastics (medical-grade PEEK, medical-grade PSU), the HTS SUPER series extruders with high-precision configuration are required. Its fully optimized screw structure and precise temperature control can ensure the dimensional accuracy of the product (tolerance ≤±0.01mm), and the clean production environment and no pollution design can meet the biocompatibility requirements of medical products; the cloud control function can realize real-time monitoring and recording of the production process, which is convenient for medical product traceability and meets the GMP (Good Manufacturing Practice) requirements of the medical field.
4.4 Aerospace Field: High Temperature Resistance, Low Weight and High Strength
The aerospace field has extremely high requirements on the performance of materials, and engineering plastics used in the aerospace field must have excellent high temperature resistance, low weight, high strength, corrosion resistance and radiation resistance. The main engineering plastics used in the aerospace field include PEEK, PI, PSU, PES, etc., which are mainly used in aerospace components, aircraft interior parts, satellite components and other products. The core requirements for extrusion processing are: ultra-high precision, ultra-high temperature resistance, stable performance, which require the extruder to have the highest level of torque, speed and temperature control capacity.
Due to the extremely strict processing requirements of aerospace-grade engineering plastics, only the HTS SUPER series extruders can meet the demand. Its ultra-high torque transmission device, maximum 1000rpm speed and fully optimized key components can cope with the high viscosity and high temperature resistance of aerospace-grade materials (long-term use temperature up to 300℃); the laser-clad screw and barrel have extremely high wear resistance and corrosion resistance, which can adapt to the processing of high-hardness modifiers (such as carbon fiber, ceramic fiber); the intelligent PLC + cloud touch screen control system can realize precise control of extrusion parameters, and the remote monitoring and predictive maintenance function can ensure the stable operation of equipment in long-term continuous production; the customizable configuration can meet the special processing needs of various aerospace components, ensuring the high performance and high reliability of the product.
4.5 Chemical Field: Corrosion Resistance and Wear Resistance
The chemical field has harsh working environment, and engineering plastics used in the chemical field must have excellent corrosion resistance, wear resistance, high temperature resistance and pressure resistance. The main engineering plastics used in the chemical field include PPS, PEEK, PVDF (polyvinylidene fluoride), etc., which are mainly used in chemical equipment, pipelines, valves, pumps and other products. The core requirements for extrusion processing are: corrosion resistance, wear resistance, stable performance, which require the extruder to have excellent wear resistance and corrosion resistance, and stable pressure control capacity.
For chemical pipelines and valves made of general corrosion-resistant engineering plastics (PPS, PVDF), the HTS PLUS series extruders are suitable. Its bimetallic composite screw and barrel have excellent corrosion resistance and wear resistance, which can adapt to the corrosion of chemical media and the wear of materials; the stable pressure control capacity can ensure the uniform wall thickness of pipelines and valves, avoiding leakage caused by uneven wall thickness. For high-pressure chemical equipment and corrosion-resistant components made of high-end corrosion-resistant engineering plastics (PEEK, PI), the HTS SUPER series extruders are required. Its ultra-high torque and stable conveying capacity can cope with the high viscosity of high-end corrosion-resistant materials, and the laser-clad screw and barrel have extremely high corrosion resistance and wear resistance, which can meet the long-term use requirements in harsh chemical environments; the precise temperature control can avoid thermal decomposition of materials, ensuring the corrosion resistance and pressure resistance of the product.
5. Common Problems and Solutions in Engineering Plastics Twin-Screw Extrusion Processing
In the actual twin-screw extrusion processing of engineering plastics, due to the influence of raw materials, processing parameters, equipment performance and other factors, various problems often occur, which affect the product quality and production efficiency. Below, we will summarize the common problems in engineering plastics extrusion processing, analyze their causes, and provide corresponding solutions combined with the characteristics of our HTS series extruders, helping enterprises solve practical processing problems and improve production efficiency.
5.1 Problem 1: Thermal Decomposition and Discoloration of Materials
Symptoms: During the extrusion process, the material appears yellowing, blackening, carbonization and other phenomena, and the final product has discoloration, bubbles, cracks and other defects, and the mechanical properties are significantly reduced. This problem is mainly caused by the sensitivity of engineering plastics to overheating and hydrolytic degradation.
Causes: 1. The extrusion temperature is too high or the temperature of a certain section of the barrel is too high, resulting in thermal decomposition of the material; 2. The residence time of the material in the extruder is too long, leading to excessive heating and decomposition; 3. The raw materials are not dried thoroughly, and the moisture in the materials causes hydrolytic degradation during high-temperature processing; 4. The screw speed is too low, resulting in insufficient shear force and prolonged residence time; 5. The flow channel of the die head is blocked, resulting in material accumulation and local overheating.
Solutions: 1. Adjust the extrusion temperature according to the type of engineering plastic, strictly control the temperature of each section of the barrel and die head within the optimal range, and use the precise temperature control function of the HTS series extruders (temperature control precision ±1℃) to avoid local overheating; 2. Increase the screw speed appropriately (within the range suitable for the material) to shorten the residence time of the material. The HTS series extruders can reach a maximum speed of 1000rpm, which can effectively shorten the residence time to 1-3 minutes; 3. Strengthen the drying treatment of raw materials, strictly control the moisture content below 0.1%-0.2%, and use the drying device matched with the HTS series extruders to prevent the raw materials from absorbing moisture again during feeding; 4. Check and clean the die head regularly to ensure the smooth flow channel, avoid material accumulation; 5. If the problem persists, adjust the screw element combination, increase the number of conveying elements, and reduce the number of mixing elements to speed up the material conveying and shorten the residence time.
5.2 Problem 2: Uneven Dispersion of Modifiers
Symptoms: The final product has uneven texture, obvious agglomeration of modifiers (such as glass fiber, carbon fiber), and the mechanical properties (strength, toughness, wear resistance) are uneven, which cannot meet the use requirements. This problem is common in the processing of modified engineering plastics.
Causes: 1. The premixing effect of raw materials is poor, and the modifiers are not uniformly adhered to the surface of the resin; 2. The screw speed is too low, resulting in insufficient shear force and kneading force, and the modifiers cannot be fully broken and dispersed; 3. The combination of screw elements is unreasonable, and the number of mixing elements and shearing elements is insufficient; 4. The extrusion temperature is too low, the material is not fully melted, and the modifiers cannot be uniformly dispersed in the resin matrix; 5. The particle size of the modifier is too large or uneven.
Solutions: 1. Optimize the premixing process, increase the mixing speed (800-1200rpm) and mixing time (5-10 minutes), add an appropriate amount of compatibilizer to improve the compatibility between the modifier and the resin, and use a high-speed mixer matched with the HTS series extruders to ensure uniform premixing; 2. Increase the screw speed appropriately, use the high-speed performance of the HTS series extruders to generate strong shear force and kneading force, and fully break the agglomerates of modifiers; 3. Adjust the combination of screw elements, increase the number of mixing elements and shearing elements, and use the modular screw design of the HTS series extruders to customize the optimal screw combination according to the type of modifier; 4. Properly increase the extrusion temperature to ensure that the material is fully melted, which is conducive to the uniform dispersion of modifiers; 5. Crush and sieve the modifier to ensure that its particle size is uniform (20-40 mesh) and meets the processing requirements.
5.3 Problem 3: Wear of Screw and Barrel
Symptoms: After a period of use, the extrusion capacity of the extruder decreases, the shear force and mixing effect are reduced, the product quality is unstable, and even the screw and barrel are stuck. This problem is mainly caused by the wear of high-hardness modifiers (such as glass fiber, carbon fiber) on the screw and barrel during the processing of reinforced engineering plastics.
Causes: 1. The screw and barrel are made of materials with poor wear resistance, which cannot resist the wear of high-hardness modifiers; 2. The filling amount of the modifier is too high (≥50%), and the wear is intensified; 3. The particle size of the modifier is too large, which increases the wear on the screw and barrel; 4. The extrusion pressure is too high, which increases the friction between the material and the screw and barrel; 5. The screw and barrel are not maintained regularly, and the material residue accelerates the wear.
Solutions: 1. Select extruders with high wear resistance, such as HTS PLUS series and HTS SUPER series. Their screws and barrels are made of imported wear-resistant alloy steel and undergo bimetallic composite treatment or laser cladding treatment, with surface hardness ≥65 HRC (HTS PLUS) and ≥70 HRC (HTS SUPER), which can effectively resist the wear of high-hardness modifiers; 2. Control the filling amount of the modifier within a reasonable range. If high filling amount is required, select the HTS SUPER series extruders with better wear resistance; 3. Crush and sieve the modifier to reduce its particle size and reduce wear; 4. Adjust the extrusion parameters to control the extrusion pressure within the optimal range (5-15MPa), avoid excessive pressure; 5. Regularly maintain the screw and barrel, clean the material residue in time, and apply lubricating oil appropriately to reduce friction and extend the service life. In addition, our professional technical team can provide regular wear detection services for the screw and barrel, and put forward targeted replacement and maintenance suggestions.
5.4 Problem 4: Unstable Product Size and Dimensional Deformation
Symptoms: The size of the extruded product (such as granules, pipes, sheets) is uneven, the shrinkage rate exceeds the standard (＞1.5%), and the product has deformation, warpage and other phenomena, which affects the assembly and use of the product.
Causes: 1. The extrusion temperature is unstable, resulting in uneven melting and plasticization of the material, and uneven shrinkage during cooling; 2. The extrusion speed is unstable, leading to uneven extrusion amount and unstable product size; 3. The cooling speed is uneven, resulting in uneven internal and external stress of the product, leading to deformation; 4. The die head structure is unreasonable, the flow channel is not smooth, and the material flow is uneven; 5. The raw materials have high water absorption, and the moisture causes uneven shrinkage during processing.
Solutions: 1. Use the precise temperature control system of the HTS series extruders to ensure the stability of the extrusion temperature, and avoid temperature fluctuation; 2. Adjust the feeding speed and screw speed to ensure the stability of the extrusion speed, and use the frequency conversion speed regulation function of the HTS series extruders to realize the synchronous adjustment of feeding and extrusion; 3. Optimize the cooling process, ensure uniform cooling speed, adjust the cooling water temperature (20-30℃) and cooling time (2-5 minutes) for strip cooling, and use air cooling or water spray cooling for pipes and sheets to avoid uneven cooling; 4. Check and optimize the die head structure, ensure the smooth flow channel, and adjust the die head temperature to ensure uniform material flow; 5. Strengthen the drying treatment of raw materials, strictly control the moisture content, and reduce the impact of moisture on product shrinkage.
5.5 Problem 5: Low Extrusion Efficiency and High Energy Consumption
Symptoms: The production capacity of the extruder is lower than the design standard, the energy consumption per unit product is high, and the production cost is increased, which affects the economic benefits of the enterprise.
Causes: 1. The screw speed is too low, the conveying capacity is insufficient; 2. The extrusion temperature is too low, the material viscosity is too high, the conveying resistance is increased, and the production capacity is reduced; 3. The combination of screw elements is unreasonable, the conveying efficiency is low; 4. The feeding device is blocked or the feeding speed is insufficient, resulting in insufficient feeding; 5. The screw and barrel are worn, the conveying capacity is reduced, and the energy consumption is increased.
Solutions: 1. Increase the screw speed appropriately (within the range suitable for the material) to improve the conveying capacity and production efficiency. The HTS series extruders can reach a maximum speed of 1000rpm, which can significantly improve production efficiency; 2. Properly increase the extrusion temperature to reduce the material viscosity, reduce the conveying resistance, and improve the conveying efficiency; 3. Adjust the combination of screw elements, increase the number of conveying elements, optimize the screw lead and compression ratio, and improve the conveying efficiency. The modular screw design of the HTS series extruders can realize the quick adjustment of screw elements; 4. Check and clean the feeding device regularly, ensure the smooth feeding, and adjust the feeding speed to match the screw speed, avoid insufficient feeding; 5. Regularly detect the wear degree of the screw and barrel, replace the worn components in time, and maintain the conveying capacity of the extruder, reducing energy consumption. In addition, the HTS series extruders adopt an optimized structural design and high-efficiency motor, which can reduce energy consumption by 15%-20% compared with ordinary extruders.
6. Conclusion and Future Development Trend
Engineering plastics, as a key high-performance material, are playing an increasingly important role in global industrial upgrading, and twin-screw extrusion technology is the core support for the high-quality processing of engineering plastics. The performance of extrusion equipment directly determines the quality, production efficiency and application effect of engineering plastic products. Our HTS series twin-screw extruders, including HTS BASIC, HTS PLUS and HTS SUPER, are specially designed for the processing characteristics of engineering plastics (sensitivity to overheating and hydrolytic degradation, high requirements on mixing and dispersing effect, high viscosity), with the advantages of high torque, high speed, precise temperature control, excellent wear resistance, wide application range and intelligent control. They can provide targeted processing solutions for different types of engineering plastics and different scales of enterprises, helping enterprises solve processing difficulties, improve product quality and production efficiency, and enhance market competitiveness.
Looking forward to the future, with the continuous upgrading of downstream industries such as automotive lightweight, electrical and electronic intelligence, new energy and medical high-endization, the demand for high-performance, functional and environmentally friendly engineering plastics will continue to grow, which will also put forward higher requirements on twin-screw extrusion technology and equipment. The future development trend of engineering plastics twin-screw extruders will be mainly reflected in four aspects:
First, intelligence and digitalization. With the development of Industry 4.0, twin-screw extruders will be more integrated with intelligent technologies such as Internet of Things, big data and artificial intelligence. The HTS series extruders will further optimize the cloud control function, realize real-time monitoring, data analysis, predictive maintenance and intelligent adjustment of the entire production process, reduce labor intervention, and improve production efficiency and product consistency. At the same time, digital simulation technology will be widely used in the design and debugging of extruders, reducing the research and development cycle and debugging time of equipment.
Second, high performance and high efficiency. The demand for high-end engineering plastics (such as PEEK, PI) will continue to increase, which will promote the continuous upgrading of extruder performance. The future extruders will have higher torque, higher speed and more precise temperature control capacity, and the key components (screw, barrel, gearbox) will be further optimized to improve wear resistance, corrosion resistance and service life. At the same time, the energy consumption of the equipment will be further reduced, realizing high-efficiency and energy-saving production.
Third, customization and diversification. Different application fields and different products have increasingly personalized requirements for extrusion processing. The future extruders will adopt a more flexible modular design, which can quickly replace screw elements, die heads and other components according to customer needs, realizing the processing of multiple varieties and small batches. At the same time, we will provide more personalized customized solutions according to the special processing needs of customers, meeting the diverse market demands.
Fourth, environmental protection and greenization. With the strengthening of global environmental protection policies, environmental protection will become an important development direction of extrusion equipment. The future extruders will adopt more environmentally friendly materials and manufacturing processes, reduce energy consumption and pollutant emissions; at the same time, they will be more compatible with recyclable engineering plastics and biodegradable engineering plastics, promoting the green development of the engineering plastics industry.
We will always adhere to the concept of technological innovation, focus on the development needs of the engineering plastics industry, continuously invest in research and development, optimize the performance of HTS series extruders, improve after-sales service, and provide more professional, efficient and intelligent twin-screw extrusion solutions for global engineering plastics processing enterprises, helping the high-quality development of the engineering plastics industry.