In traditional manufacturing, automotive parts, home appliances, machinery equipment, valves, and hardware industries, choice of plastic materials directly determines product strength, service life, dimensional stability, and assembly reliability. Different materials vary greatly in toughness, heat resistance, wear resistance, chemical resistance, and processing characteristics. Choosing wrong material can easily lead to problems such as deformation, cracking, wear, and poor fit.

 

This article compiles information on the 15 most commonly used engineering and general-purpose plastics in injection molding, providing a systematic and easy-to-understand explanation of material characteristics, inherent weaknesses, chemical compatibility, assembly points, and practical application scenarios. It is an essential practical reference for technical, production, quality, and design personnel.

Characteristics: Low density, good toughness, flexural strength, fatigue resistance, excellent flowability, low cost, resistant to acid, alkali, and salt solutions, long-term operating temperature 80–100℃.
Weaknesses: Brittle at low temperatures, moderate weather resistance, relatively high shrinkage, difficult to print on, difficult to bond.
Compatibility: Resistant to most chemicals, but not resistant to strong oxidizers.
Assembly Points: Suitable for snap-fit connections, screw-on structures, ultrasonic welding, and thermal welding; not suitable for strong structural adhesives.
Application Examples: Automotive air ducts, protective panels, battery housings, appliance housings, valve bases, insulating parts, and everyday structural components.

Characteristics: Balanced rigidity and toughness, good impact resistance, high surface gloss, easy to electroplate and paint, strong dimensional stability.
Weaknesses: Moderate heat resistance (80–90℃), not resistant to strong solvents, and has average weather resistance.
Compatibility: Resistant to oils and weak acids and alkalis, but not resistant to ketones and aromatic hydrocarbon solvents.
Assembly Points: Can be glued, ultrasonically welded, and screwed; suitable for precision snap-fit assembly.
Application Examples: Automotive interior parts, instrument panel housings, door handles, rearview mirror housings, appliance panels, and electronic structural components.

Properties: High strength, good toughness, wear resistance, oil resistance, heat resistance 100–110℃, good flowability, easy to mold.
Weaknesses: High hygroscopicity; significant dimensional change after water absorption, decreased rigidity; prone to hydrolysis at high temperatures.
Compatibility: Good oil and solvent resistance, but not resistant to strong acids and alkalis.
Assembly Points: Suitable for precision gear, clip, and insert assembly. Ambient humidity must be controlled before use to avoid dimensional fluctuations.
Application Examples: Automotive wiring harness brackets, clips, gears, oil pump components, valve fitting plastic parts, wear-resistant structural parts.

Properties: Higher strength, rigidity, and heat resistance than PA6; long-term operating temperature 120–150℃; excellent fatigue resistance and wear resistance.
Weaknesses: High water absorption, prone to hydrolysis at high temperatures, significant shrinkage.
Compatibility: Excellent oil and chemical resistance, but not resistant to strong acids and alkalis.
Assembly Points: Suitable for high-temperature, high-load structural components. Drying is recommended before assembly to ensure dimensional stability.
Application Examples: Engine peripheral parts, bearing housings, fan blades, terminal blocks, high-strength clips.

Characteristics: High rigidity, extremely strong dimensional stability, good self-lubrication, wear-resistant, fatigue-resistant, oil-resistant, performance close to metal.
Weaknesses: Not resistant to high temperatures, not resistant to strong acids and alkalis, easily decomposes into formaldehyde at high temperatures, poor weather resistance.
Compatibility: Good oil and solvent resistance, not resistant to strong oxidizers.
Assembly Points: Suitable for precision sliding parts, gears, and bushings. Avoid strong impacts during assembly to prevent stress cracking.
Application Examples: Automotive door locks, valve cores, guide rails, bearings, gears, precision structural components.

Characteristics: High transparency, extremely high impact strength, heat resistance 120–130℃, dimensional stability, good flame retardancy. Weaknesses: Prone to stress cracking, sensitive to notches, moderate chemical resistance, high processing temperature.
Compatibility: Resistant to weak acids and alkalis, but not resistant to esters and ketones.
Assembly Points: Avoid excessive interference fit, use moderate assembly force, suitable for ultrasonic welding and gluing.
Application Examples: Automotive headlight covers, instrument panels, transparent windows, charger housings, safety structural components.

Characteristics: High strength, good heat resistance, chemical corrosion resistance, low water absorption, dimensional stability, easy to mold.
Weaknesses: Moderate low-temperature toughness, prone to anisotropic shrinkage.
Compatibility: Oil-resistant, solvent-resistant, good weather resistance.
Assembly Points: Suitable for screw fixing, connectors, and precision assembly of terminals; high stability.
Application Examples: Automotive connectors, coil frames, terminal blocks, electronic and electrical structural components.

Characteristics: High strength, good rigidity, weather-resistant, chemical-resistant, low water absorption, strong dimensional stability.
Weaknesses: Narrow processing temperature range, prone to warping and deformation.
Compatibility: Good oil and solvent resistance.
Assembly Points: Suitable for high-strength structural components and housing assembly; structurally stable and not easily deformed.
Application Examples: Automotive structural components, electronic housings, high-strength functional components.

Characteristics: Soft and elastic, comfortable to touch, adjustable hardness, can be overmolded with hard rubber, simple processing.
Weaknesses: Low heat resistance (60–80℃), low overall strength, prone to swelling upon contact with oil.
Compatibility: Resistant to weak acids and alkalis, not resistant to oils and ester solvents.
Assembly Points: Mostly used for overmolding, anti-slip, sealing, and cushioning; not suitable for bearing heavy loads.
Application Examples: Automotive buttons, grips, sealing strips, shock absorbers, tool overmolded handles.

 

Characteristics: Good elasticity, higher strength than TPE, wear-resistant, oil-resistant, resistant to repeated bending, long service life.
Weaknesses: Moderate heat resistance, prone to hydrolysis at high temperatures, higher price than ordinary TPE.
Compatibility: Good oil and solvent resistance.
Assembly Points: Suitable for sealing, cushioning, and wear-resistant soft rubber parts; can be laminated with hard rubber through secondary injection molding.
Application Examples: Automotive dust covers, oil pipe sleeves, seals, casters, wear-resistant soft rubber parts.

Characteristics: Good toughness, low-temperature resistance, extremely strong chemical resistance, low cost, excellent flowability.
Weaknesses: Low rigidity, prone to creep, difficult to print on, difficult to bond.
Compatibility: Resistant to most acids and alkalis; extremely chemically stable.
Assembly Points: Suitable for heat welding and snap-fit connections; not suitable for adhesive bonding.
Application Examples: Insulating parts, hoses, linings, containers, low-load structural parts.

Characteristics: High rigidity, good transparency, easy to mold, low cost.
Weaknesses: Brittle, poor impact resistance, low heat resistance, prone to cracking upon impact.
Compatibility: Resistant to weak acids and alkalis, not resistant to organic solvents.
Assembly Points: Only suitable for light-load assembly; avoid hammering, squeezing, and interference fits.
Application Examples: Liners, packaging, shells, decorative parts.

Characteristics: High transparency, good weather resistance, high surface gloss, strong appearance and texture.
Weaknesses: Brittle, easily scratched, moderate chemical resistance, prone to stress cracking.
Compatibility: Resistant to weak acids and alkalis, not resistant to ketones and ester solvents.
Assembly Points: Avoid interference fits; suitable for screw pressing, not suitable for strong adhesive fixing.
Application Examples: Transparent covers, lenses, decorative panels, automotive headlight covers.

Characteristics: High heat resistance, low water absorption, extremely stable dimensions, good flame retardancy, hydrolysis resistance, and resistance to damp heat.
Weaknesses: Relatively high price, moderate fluidity.
Compatibility: Excellent chemical resistance, oil resistance, and hot water resistance.
Assembly Points: High-end precision structural components, dimensionally stable at high temperatures, suitable for harsh working conditions.
Application Examples: Automotive water pump components, electronic housings, high-temperature structural components, fluid control components.

Characteristics: Low cost, good chemical resistance, flame retardant, adjustable hardness (soft/hard).
Weaknesses: Low heat resistance, easily decomposes at high temperatures, subject to numerous environmental restrictions.
Compatibility: Good acid and alkali resistance, moderate oil resistance.
Assembly Points: Suitable for low-temperature processing and assembly, not suitable for high-temperature welding and high-strength structural components.
Application Examples: Wire sheaths, hoses, seals, low-end housings, insulating components.
Choosing right materials minimizes product development pitfalls; a thorough understanding of properties makes manufacturing much more efficient.
Mastering properties of plastics is core foundation for improving product quality, reducing defect rates, and extending product lifespan.
Understanding materials is essential for successful manufacturing.