In the field of machining, choosing the right plastic for machining is the core prerequisite for ensuring product performance and improving processing efficiency. The properties of different plastics vary significantly, and the application scenarios they are suitable for are also different. This article will focus on 7 types of plastics that are most suitable for machining, break down the characteristics, advantages and typical applications of each material in detail, and provide practical selection suggestions based on real cases to help you accurately match materials according to your own processing needs, and finally supplement professional views and FAQs to provide a comprehensive reference for the selection of plastic for machining.
1. Introduction
With the development of the manufacturing industry towards precision and lightweight, the proportion of plastics in machining continues to increase. According to industry data, engineering plastics will account for 58% of the global machining plastics market in 2024, an increase of 12 percentage points from 2020. Compared with metals, plastics have the advantages of low processing energy consumption, good insulation, corrosion resistance, and flexible molding, and are widely used in electronics, automotive, medical, chemical and other industries. However, not all plastics are suitable for machining, and plastics with good dimensional stability, processing consistency and mechanical properties can better meet the processing needs. Here are 7 plastics that are best suited for machining applications.
2. Polyoxymethylene (POM)
2.1 Features and Benefits
POM is known as "super steel" and is one of the preferred materials in plastic for machining. Its core characteristics include: high crystallinity, excellent dimensional stability, stable shrinkage rate of 1.5%-2.0%, and not easy to deform after processing; It has excellent wear resistance and fatigue resistance, low friction coefficient (0.1-0.3), and can withstand reciprocating motion for a long time. High mechanical strength, tensile strength can reach more than 60MPa, close to some metal materials. In addition, POM has good machining performance, is not easy to produce burrs when cutting, and the machining accuracy is easy to control, making it suitable for mass production of high-precision parts.
2.2 Application fields
POM is widely used in scenarios that require high precision and wear resistance, typical cases include: a precision machinery manufacturer uses POM to process micro transmission gears, compared with metal gears, the processing efficiency is increased by 40%, the noise is reduced by 25 decibels, and the service life is extended by 3 times; In the automotive industry, POM is used to process parts such as gearbox sliders and throttle bodies, which can effectively improve the movement stability of components. In the electronics industry, POM can make precision accessories such as keyboard keys and connectors to ensure smooth operation.
3. Polycarbonate (PC)
3.1 Features and Benefits
PC is an amorphous engineering plastic, the core advantage is that the impact resistance is extremely strong, the impact strength is 250 times that of ordinary glass, 30 times that of acrylic; High light transmittance (up to 90%), close to glass, and good UV resistance; It has excellent thermal stability, with a thermal deformation temperature of more than 130°C and can work stably in an environment of -40°C to 120°C. At the same time, PC machining is highly adaptable and can be formed through various processing methods such as cutting, drilling, and milling, making it suitable for making transparent or load-bearing parts with complex structures.
3.2 Applications
The application of PC is concentrated in scenarios that require transparency and impact resistance: in the medical industry, a medical device company uses PC to process surgical instrument protective covers, which can not only resist collision damage, but also ensure that medical staff can clearly observe the operation process; In the electronics industry, PCs are used to make mobile phones, computer shells and display screen protectors; In the automotive industry, PC can process lampshades, dashboards and other components, which have both light transmission and impact resistance. In the aerospace field, PCs are used to make transparent panels for aircraft interiors.
4. Polystyrene (PS)
4.1 Features and Benefits
PS is a general-purpose plastic with excellent processing performance, and its core characteristics include: good rigidity, tensile strength of more than 40MPa; Excellent processing fluidity, fast prototyping, low resistance during cutting, and efficient production of high-precision simple structural parts; The cost is low, compared with engineering plastics, the price is 30%-50% lower, suitable for mass production of low value-added parts. However, PS is more brittle, has poor impact resistance, and average chemical resistance, making it not suitable for stress or exposure to chemicals.
4.2 Applications
PS is suitable for processing general parts with low performance requirements, and typical applications include: In the electronics industry, an electronic component manufacturer uses PS to make component trays, because its processing accuracy is easy to control, which can better protect the components from damage; In the packaging industry, PS can process foam cushioning materials and food packaging boxes; In the field of office equipment, PS is used to make the shell and internal support parts of printers and copiers; In the toy industry, PS is a common material used to make plastic toys, and complex shapes can be achieved through injection molding.
5. Polypropylene (PP)
5.1 Features and Benefits
PP is a cost-effective plastic for machining, the core advantage is excellent chemical resistance, can withstand the corrosion of most acids and alkalis (such as hydrochloric acid, sulfuric acid, sodium hydroxide, etc.), oil and solvent; Good toughness, strong impact resistance, even in a low temperature environment of -20°C, it can still maintain good toughness; Light weight, density only 0.91g/cm³, one of the smallest density varieties among common plastics; The processing difficulty is low, cutting, welding, and forming are easy to achieve, and the processing scrap rate is low.
5.2 Applications
The application of PP focuses on chemical resistance and lightweight scenarios: in the chemical industry, a chemical enterprise uses PP to process and transport hydrochloric acid pipes, and there is no corrosion and leakage phenomenon after 5 years of use, far exceeding the service life of traditional metal pipes; In the automotive industry, PP is used to process bumpers, interior panels and other components, which can effectively reduce the weight of the body; In the food industry, PP can make food packaging containers, infusion sets, etc., because it is non-toxic, odorless, and meets food-grade standards; In the construction industry, PP is used to process water supply and drainage pipes and ventilation pipes.
6. Polyvinyl chloride (PVC)
6.1 Features and Benefits
PVC is a widely used general-purpose plastic, and its core characteristics include: good flame retardancy, which can meet the V0 flame retardant standard without adding additional flame retardants; The mechanical strength is moderate, with a tensile strength of more than 50MPa, which can meet the stress requirements of most general parts. Excellent weather resistance, can resist the erosion of natural environments such as ultraviolet rays, wind and rain, and is not easy to age after long-term outdoor use; It has low cost and mature processing technology, making it suitable for large-scale production. However, it should be noted that PVC processing is easy to decompose and produce toxic gas at high temperatures, and the processing temperature needs to be controlled.
6.2 Applications
PVC is suitable for processing flame retardant and weather-resistant parts, typical applications include: in the construction industry, PVC is the core material for making door and window profiles, floor leather, wallpaper, a building materials manufacturer uses PVC processing door and window profiles, the service life can reach more than 20 years; In the electronics industry, PVC is used to make insulation layers for wires and cables, which have both insulation and flame retardant. In the medical industry, PVC can process consumables such as disposable infusion tubes and urinary catheters; In the chemical industry, PVC is used to make small chemical storage tanks, valves and other components.
7. Polyamide (PA)
7.1 Features and Benefits
PA (nylon) is a high-performance engineering plastic, the core advantage is high mechanical strength, tensile strength can reach more than 80MPa, excellent wear resistance, low friction coefficient, suitable for making transmission parts; Good toughness, strong impact resistance, can withstand large impact loads; Excellent oil resistance and long-term operation in oily environments. However, PA has strong hygroscopicity, and undried materials are prone to dimensional deformation after processing, so they need to be dried at 120°C for 4-6 hours in advance, and annealing is needed to release internal stress after processing.
7.2 Applications
PA is widely used in transmission and oil-resistant scenarios: in the automotive industry, an auto parts manufacturer uses PA to process engine valve covers, intake manifolds and other components, which reduce the weight by 30% compared with metal parts, and have good oil resistance and stable service life; In the machinery industry, PA is used to make precision bearings, gears, racks and other transmission parts, and the bearings processed by PA in a machinery factory can still work normally for more than 5,000 hours without lubrication; In the electronics industry, PA can be used to make connectors, terminals, and other components to ensure the stability of connections.
8. Polytetrafluoroethylene (PTFE)
8.1 Features and Benefits
PTFE is known as the "plastic king", which is the best plastic for machining, which can withstand almost all known acids and alkalis, solvents and oxidants, including aqua regia, hydrofluoric acid and other highly corrosive substances. The friction coefficient is extremely low (0.04), which is the smallest friction coefficient among solid materials, and has excellent self-lubricating performance. It has good high temperature resistance, and the operating temperature range is -200°C to 260°C, which can work stably in extremely high temperature environments. However, PTFE processing is difficult, the melt fluidity is poor, and special processing technology is required, and the cost is high.
8.2 Applications
PTFE is suitable for machining precision parts in extreme environments: In the aerospace field, PTFE is used to make seals, conduits and other components of aircraft engines, which can adapt to high temperatures, high pressures and corrosive environments; In the chemical industry, a high-end chemical enterprise used PTFE to process the sealing gasket of the reactor, which has not leaked for 10 years after being used in a strong corrosive medium; In the medical industry, PTFE is used to make implantable medical devices such as artificial blood vessels and heart valves, which will not cause rejection reaction due to its good biocompatibility. In the electronics industry, PTFE is used to make insulating components for high-frequency communication equipment.
9. Suggestions for choosing suitable plastics
9.1 Consider Mechanical Properties
Select according to the stress and working environment of the parts: if the parts are long-term friction stress components such as transmission gears and bearings, give priority to materials with good wear resistance such as POM, PA, PTFE, etc.; If the parts are protective covers, shells and other impact-resistant parts, materials with good toughness such as PC and PP are more suitable; If the parts need to work in a high-temperature environment, the thermal stability of PTFE, PC, POM is better; If the parts need to be exposed to chemicals, prefer materials with strong chemical resistance, such as PTFE and PP.
9.2 Consider cost and machinability
When mass production of low value-added parts, you can choose materials such as PS, PP, PVC, etc., which are low cost and simple to process; When producing high-precision and high-demand precision parts, it is necessary to choose high-performance materials such as POM, PA, and PTFE, which can improve product life and reliability although the cost is high. At the same time, it is necessary to combine its own processing equipment conditions: small processing plants with simple equipment give priority to PP, PS and other materials with low processing difficulty; Enterprises with professional equipment and technology can choose materials such as PTFE and PC, which are difficult to process but have better performance.
10. Conclusion
The above 7 plastics are the preferred categories of plastic for machining, each with its own unique advantages and adaptation scenarios: POM is suitable for precision transmission scenarios, PC is good at transparent impact resistance scenarios, PS is suitable for low-cost general scenarios, PP has advantages in chemical resistance and lightweight, PVC focuses on flame retardant and weather resistance, PA is suitable for transmission oil resistance, and PTFE is suitable for extreme corrosion and high-temperature environments. When choosing, it is necessary to comprehensively consider the mechanical performance requirements, working environment, cost budget, and processing conditions of the parts to achieve accurate matching of materials and applications, and improve processing efficiency and product competitiveness.
Yigu Technology Perspective
Yigu Technology believes that the core of plastic for machining selection is "performance adaptation + cost balance". At present, the requirements of the manufacturing industry for plastic processing are becoming more and more refined, and it is difficult for a single material to meet the needs of complex scenarios. Enterprises should give priority to materials with matching properties based on their own product characteristics, and at the same time, they can use modification technology to improve material properties (such as enhancing the dimensional stability of PA). In addition, in-depth cooperation with professional material suppliers to obtain targeted processing technology suggestions can effectively reduce processing risks, improve product quality, and maximize benefits.
FAQ
1. Batch processing of high-precision parts, which plastic for machining is preferred? Preferential choice of POM, which has excellent dimensional stability, easy control of processing accuracy, and high processing efficiency, is suitable for mass production; If the part needs to be oil-resistant, you can choose dry-treated PA to ensure accuracy and meet the requirements of oil resistance.
2. Which material is more suitable for plastic parts for outdoor use? Prefer PVC or PP, both of which have excellent weather resistance, can resist ultraviolet rays and wind and rain erosion, and are not easy to age in long-term outdoor use. If transparency is required, you can choose PC with anti-UV agent.
3. Is PTFE necessary for machining parts exposed to highly corrosive chemicals? Not necessarily. If the chemical is ordinary acid and alkali, the chemical resistance of PP can meet the demand, and the cost is much lower than that of PTFE. If you are exposed to highly corrosive substances such as aqua regia and hydrofluoric acid, or work in a high-temperature corrosive environment, you must choose PTFE.
4. How to solve the dimensional deformation problem after PA machining? The core is to do a good two-step treatment: dry the PA material at 120°C for 4-6 hours before processing to completely remove the moisture; After processing, the parts are annealed (100°C insulation for 2 hours) to release internal stress, which can effectively reduce dimensional deformation.
