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Engineering plastic properties
Compare material properties before choosing an engineering plastic for a real part.
Use this guide to connect heat resistance, chemical resistance, wear, strength, stiffness, dimensional stability and electrical behavior to material selection, stock shape, machining and RFQ decisions.
Short answer
Material properties only help when they are tied to the operating environment.
Engineering plastic properties should not be read as isolated numbers. A material that looks strong at room temperature may creep under load, swell with moisture, soften near heat, crack under chemicals or move after machining. Start with the part function, then compare the property group that controls failure risk.
Property map
Match the property group to the engineering question.
| Property group | What it helps answer | Common material directions | What to confirm before RFQ |
|---|---|---|---|
| Heat resistance | Will the part keep stiffness, shape and function at service temperature? | PEEK, PPS, PEI, PI, PAI, PPSU, PTFE | Continuous vs peak temperature, load while hot, chemical exposure and tolerance needs. |
| Chemical resistance | Will the part survive contact with fluids, cleaners, fuels or process chemicals? | PTFE, PEEK, PPS, PVDF, PP, PE | Chemical name, concentration, temperature, exposure time and stress level. |
| Wear and friction | Will sliding, rolling or rubbing surfaces last without galling or excessive wear? | POM, nylon, UHMW, PTFE, PEEK, filled grades | Load, speed, mating material, lubrication, debris and replacement interval. |
| Strength and stiffness | Will the part carry load without bending, cracking or permanent deformation? | PEEK, PAI, PI, PEI, PC, POM, filled nylon | Load direction, impact, wall thickness, ribs, creep and safety factor. |
| Dimensional stability | Will the part hold size after machining, storage and use? | POM, PET, PPS, PEEK, PEI, filled grades | Moisture, temperature cycles, internal stress, flatness and tight fits. |
| Electrical behavior | Does the part need insulation, dielectric strength, ESD control or low conductivity? | PEI, PEEK, PPS, PC, PTFE, ESD grades | Voltage, dielectric need, static control, heat and certification requirements. |
Material families
Use properties to narrow the shortlist, then validate the grade.
PEEK
High heat, chemical resistance, strength and dimensional stability make PEEK a premium option for demanding parts. Review cost and whether PPS, PEI or POM can meet the duty.
PPS
Strong chemical and heat resistance with good dimensional stability. Often useful for pump, valve, electrical and under-hood environments.
PEI
Good heat resistance, stiffness, flame behavior and electrical insulation. Useful when PEEK-level performance is not required.
POM and PET
Practical choices for precision machined mechanical parts where low friction, wear resistance and stable dimensions matter.
Nylon
Tough and wear resistant, but moisture absorption can change dimensions. Review humidity and fit-critical features.
PTFE, UHMW and PVDF
Useful for low friction, chemical contact or non-stick behavior. Review creep, softness, wear mode and tolerance expectations.
Property review workbench
Turn operating conditions into a focused material shortlist.
Inputs that make property selection useful
A property chart is only the starting point. The best material shortlist comes from the part function, the service environment and the manufacturing route that will turn stock or resin into the final part.
- Primary failure risk: heat softening, chemical attack, wear, creep, cracking, swelling, electrical failure or cosmetic damage.
- Use conditions: continuous temperature, peak temperature, chemical name, load, speed, moisture and cleaning cycle.
- Part format: sheet, rod, tube, machined part, printed prototype, molded component or replacement part.
- Decision boundary: lowest practical cost, highest performance, stable supply, tight tolerance, documentation or fast prototype.
Property trade-offs
Strong material choices usually balance one property against another.
| If you optimize for | Watch the trade-off | Practical selection move |
|---|---|---|
| High temperature | Higher material cost, tougher machining, stock availability and tolerance movement under load. | Compare PEEK, PPS, PEI, PAI and PI against the actual continuous temperature and load. |
| Chemical resistance | Softness, creep, lower stiffness or poor thread strength in some chemical-resistant plastics. | Match the chemical, concentration and temperature, then review wall thickness and sealing geometry. |
| Low friction | Creep, wear debris, lower strength or looser tolerance after service. | Review load, speed, mating surface and lubrication before choosing PTFE, POM, UHMW, nylon or filled PEEK. |
| Dimensional stability | Material may be less impact-resistant, more expensive or more sensitive to machining stress. | Pair material choice with realistic tolerance, stress relief, stock form and inspection plan. |
| Electrical behavior | ESD fillers can change mechanical, wear, color or cleanliness behavior. | Separate insulation, dielectric strength, static control and clean-environment requirements. |
Selection path
Turn property research into a material decision.
| Step | Question to answer | Common mistake |
|---|---|---|
| 1. Define environment | What heat, chemicals, moisture, load, wear and electrical conditions will the part see? | Choosing from a generic property table without service conditions. |
| 2. Rank failure risks | Is the main risk softening, cracking, swelling, wear, creep, insulation failure or dimensional movement? | Optimizing one property while ignoring the real failure mode. |
| 3. Shortlist materials | Which material families meet the critical properties with realistic cost and availability? | Jumping to PEEK when PPS, PEI, POM or nylon may satisfy the application. |
| 4. Check stock and process | Is the material available as sheet, rod, tube, plate, filament or molding resin for the part geometry? | Selecting a material that is hard to source in the required form. |
| 5. Review drawing risk | Do tolerances, wall thickness, holes, flatness and surface finish match plastic behavior? | Applying metal-style tolerances to moisture- or heat-sensitive plastics. |
Manufacturing fit
Properties also change the production route.
CNC machining
Best when stock-shape material behavior, precision features and low-volume production matter.
Custom cutting
Useful for sheet, plate, rod or tube blanks where the material form already solves most of the problem.
3D printing
Good for geometry and fit validation, but printed properties may differ from machined stock or molded resin.
Injection molding
Useful when resin, geometry and demand are stable enough to justify tooling and repeated production.
Drawing review
Property selection improves when the drawing shows what the part must survive.
A material request like “heat resistant plastic” or “chemical resistant plastic” is not enough. A useful drawing package explains the operating environment and identifies the features that actually control part performance.
- Mark critical dimensions, mating faces, sliding surfaces, sealing zones and cosmetic surfaces.
- State temperature range, chemical exposure, load direction, wear mode and electrical requirements.
- State whether material documents, traceability, inspection or regulatory paperwork are required.
- Tell us whether the part is for prototype, replacement, fixture use, pilot run or production release.
Application matrix
Use application context to prioritize properties.
| Application context | Property priority | Likely material direction |
|---|---|---|
| Pump, valve and chemical equipment | Chemical resistance, temperature, creep and sealing stability. | PTFE, PEEK, PPS, PVDF, PFA or selected PE/PP grades. |
| Wear strips, guides and rollers | Wear resistance, friction, impact and dimensional stability. | POM, nylon, UHMW, PTFE-filled grades or PEEK. |
| Electrical and semiconductor fixtures | Heat, dimensional stability, dielectric behavior, cleanliness and ESD needs. | PEI, PEEK, PPS, PAI, PI or ESD-capable grades. |
| Automotive and machinery parts | Heat, wear, vibration, impact, chemical exposure and cost balance. | POM, nylon, PPS, PEEK, PC or filled engineering plastics. |
| Transparent guards and covers | Impact, clarity, UV, heat, chemical cleaning and scratch risk. | PC, acrylic, PETG or selected specialty transparent materials. |
Related pages
Continue from properties to material and manufacturing review.
FAQ
Questions buyers ask about engineering plastic properties.
What engineering plastic properties matter most?
The most important properties depend on the application, but common decision points include temperature resistance, chemical resistance, wear, strength, stiffness, creep, moisture absorption, dimensional stability and electrical behavior.
Which engineering plastics resist high temperature?
PEEK, PI, PAI, PPS, PEI, PPSU and selected fluoropolymers are often reviewed for high-temperature applications, but grade, load, chemical exposure and manufacturing route should be defined before selection.
Which plastics are good for wear and low friction?
POM, nylon, UHMW, PTFE, PEEK and filled grades are common wear or low-friction candidates. The best choice depends on load, speed, temperature, mating surface and lubrication.
What is the difference between chemical resistance and dimensional stability?
Chemical resistance describes how the material responds to fluids or cleaners. Dimensional stability describes how well the part holds size under temperature, moisture, stress and machining conditions.
Can a lower-cost plastic replace PEEK?
Sometimes. PPS, PEI, POM, nylon, PTFE or PVDF may be suitable when the real temperature, chemical, wear and load requirements are below PEEK-level demand.
Can material properties be quoted from a drawing?
Yes. A drawing or model plus operating conditions helps review material properties, stock form, manufacturing route, tolerance, inspection and RFQ requirements.
Material property review
Send drawings and use conditions before locking the plastic grade.
Include drawing or 3D model, material target, temperature, chemical exposure, load, wear, electrical needs, quantity, tolerance, surface finish, inspection needs and target lead time.