Characteristics and application of common engineering plastics
2022-07-31 318
Characteristics and application of common engineering plastics
Engineering plastics are widely used in mechanical equipment, automotive electronics and various engineering structures because of their low density, excellent mechanical, electrical, chemical and heat resistance, good wear reduction and dimensional stability.
Engineering plastics are high polymer materials. This paper mainly introduces the following from their characteristics and applications:
Polyoxymethylene (POM)
Polyamide / nylon (PA)
Polycarbonate (PC)
ABS resin (ABS)
Polytetrafluoroethylene (PTFE)
Organic glass (PMMA)
Polyphenylene oxide (PPO)
Polyoxymethylene (POM)
Features: high rigidity, hardness and tensile strength; The fatigue strength and rigidity are higher than those of nylon; Good self-lubricating performance, good wear resistance, friction coefficient of 0.15 ~ 0.35; Long term service temperature (-40 ~ 100 ℃), stable size, small creep and good electrical insulation; However, the density is high, and the acid resistance and flame retardancy are poor.
Usage: general structural parts with certain strength requirements, wear-resistant transmission parts working under light load, no lubrication or less lubrication conditions, such as various bearings, shaft sleeves, gears, automobile leaf spring bushings in the automotive industry.
(creep: under the condition that the stress remains constant, the strain increases with time, that is, under the stress condition, the plastic extends slowly along the stress direction.)
Polyamide / nylon (PA)
Features: high strength, good toughness, stiffness, fatigue resistance, oil resistance, corrosion resistance and good self lubrication. However, the water absorption is very large, which affects the dimensional stability and reduces the mechanical properties to a certain extent.
Usage: used for making all kinds of bearings, gears, impellers, bushings, transmission belts, damping pads, nylon ropes, sealing rings and cams, electrical bellows, etc.
Polycarbonate (PC)
Features: low density, excellent impact strength, good heat resistance and dimensional stability, non-toxic, transparent, not easy to fire, and easy to process and shape.
Application: it is used in construction plate, auto parts, medical devices, aerospace, electronic appliances, optical lens, optical disc basic materials, LED lighting, such as automotive dashboard, socket, vacuum cleaner handle, gear, etc.
ABS resin (ABS)
Features: tough and hard, good wear resistance, oil resistance, corrosion resistance and dimensional stability. Low temperature impact resistance is good, and the use temperature range is - 40 ~ 100 ℃. It is easy to form and machine, but it can dissolve, swell or stress crack in organic solvents.
Applications: in the mechanical industry, it is used to manufacture gears, bearings, motors and various instrument housings, handrails on automobiles, and steering wheels. In addition, it can also be used for textile equipment, electrical parts, musical instruments, furniture, etc.
Polytetrafluoroethylene (PTFE)
Features: it has good mechanical properties in a wide range (it can be safely used from -250 ° to 260 °), high chemical stability, corrosion resistance to strong acids, bases, oxidants and organic solvents, and is known as the "king of plastics". It has good wear reduction performance. Its static friction coefficient is smaller than that of plastics. Its friction coefficient to metal is 0.07-0.14, its friction coefficient to itself is 0.04, and it is also an excellent electrical insulation material, The disadvantage is low strength and poor rigidity.
Usage: parts and components on chemical equipment, such as lining or coating, as anti-wear self-lubricating parts, such as bearings, piston rings, sealing rings, etc., as electrical insulation materials and parts.
Organic glass (PMMA)
Features: excellent light transmittance, certain heat and cold resistance, corrosion resistance, good insulation performance, stable size, easy to form, but general mechanical strength, low surface hardness, easy to be scratched by hard objects.
Usage: transparent parts with certain strength are required, such as window glasses on aircraft and cars, optical instruments used in construction, electrical and other fields, as well as various transparent models, decorations, billboards, etc.
Polyphenylene oxide (PPO)
Features: high strength, good heat resistance, good mechanical properties under high temperature, long-term use temperature range (- 170 ~ +190 °), low molding shrinkage and stable size.
Usage: it is suitable for wear-resistant transmission parts under high temperature, such as precision gears, bearings, etc., and can be used as medical instruments with shells to replace stainless steel. It is used as pump impeller, valve, pipeline, etc. in chemical equipment.