Plastics Engineering Thermoplastics, High‑Performance Polymers & Processing
A practical guide to plastic materials used in product development: material families, tradeoffs, typical applications, molding/processing notes, additives and testing. Use this guide to select candidate resins, anticipate manufacturing impacts and plan validation tests for NPI and production.
- High‑performance polymers (PEEK, PEI), engineering thermoplastics (PA, POM, PC) and commodity resins
- Molding processes: injection, overmold, extrusion, blow molding, thermoforming
- Additives, fillers, flame retardancy, glass‑fill tradeoffs and tool wear considerations
Material Families & Typical Uses
High‑Performance Polymers
PEEK, PEI (ULTEM), PPS used for high temp, chemical exposure, electrical insulation and demanding mechanical loads.
Engineering Thermoplastics
PA (Nylon), POM (Acetal), PC, PBT, PET structural components, gears, housings, connectors and functional assemblies.
Commodity Plastics
ABS, PP, HDPE, LDPE housings, consumer parts, low cost enclosures and large thin‑wall sections.
High‑Performance Polymers (PEEK / PEI / PPS)
Properties & tradeoffs
High Tg and continuous use temperatures (PEEK up to ~250°C) Excellent chemical resistance and dimensional stability Higher raw material cost and specialized processing equipment
Manufacturing notes
Requires high‑temperature molds, controlled drying, and often slower cycle times. Tooling must accommodate high melt temps and potential abrasion for filled variants.
Engineering Thermoplastics PA, POM, PC, PBT, PET
These are the workhorses for structural, moving and load‑bearing plastic parts. Glass fill and mineral fill variants extend modulus and heat deflection but affect tool wear and impact strength.
PA66 / PA6
Good toughness and wear resistance; hygroscopic — design for moisture absorption and dimensional change.
POM (Acetal)
Low friction and excellent dimensional stability for gears and sliding components.
PC (Polycarbonate)
High toughness and optical grades available; prone to scratching without coatings.
Additives, Fillers & Flame Retardants
Additives tailor properties: glass or mineral fillers increase stiffness; flame retardants meet safety standards; anti‑UV, antioxidants and pigments add durability and appearance. Each additive affects flow, mechanical behavior and processing.
Glass Fill
Increases modulus and dimensional stability; increases density and tool wear.
Mineral Fill
Reduces CTE, can improve thermal mass; may reduce impact strength.
Flame Retardants
Halogenated or non‑halogenated chemistries consider environmental and RoHS constraints.
Molding & Forming Processes
Choose the process that aligns with geometry, volumes and material: injection molding for complex high‑precision parts; overmolding for multi‑material assemblies; extrusion for continuous profiles; blow molding for hollow containers; thermoforming for large thin shells.
Injection Molding
Best for complex, repeatable parts; supports multi‑cavity and family tooling.
Overmolding / Insert Molding
Integrate elastomeric seals or soft touch features onto rigid substrates to reduce assembly.
Extrusion/Blow/Thermoform
Used for continuous profiles, hollow parts and sheet forming respectively; lower tooling cost for some geometries.
Design for Molding (DFM) Guidance
Good DFM reduces cycle time, rejects and cost. Key guidance includes uniform wall thickness, appropriate draft, gentle radii, well‑placed ribs and bosses, gate location, and avoiding thick sections that cause sink & internal stresses.
| Design Item | Good Practice | Notes |
|---|---|---|
| Wall thickness | Keep uniform & thin where possible | Varies by material — consult resin datasheet |
| Ribs & bosses | Use ribs for stiffness; boss thickness ≤ 0.6× wall | Gusset ribs reduce sink |
| Draft | ≥ 0.5° (cosmetic) to 2°+ (textured) | Increase for textured surfaces |
| Gate location | Place to balance flow and minimize weld lines | CAE helps optimize |
Sustainability & Recyclability
Design for recyclability by minimizing mixed materials and using compatible adhesives/coatings. Thermoplastics are generally recyclable; consider PCR (post‑consumer recycled) content and the tradeoff with mechanical properties. Document material composition for end‑of‑life processing.
Practical steps
- Prefer single‑polymer constructions where possible
- Avoid incompatible coatings that contaminate recycling streams
- Specify recyclability and PCR content targets early in product design
Testing, Validation & Regulatory
Common tests
Tensile, flexural, Izod/Charpy impact HDT, Vicat softening, TGA/DSC Flammability (UL94), CTI for electrical insulation
Compliance
RoHS / REACH declarations FDA / EU food contact approvals where applicable Medical: ISO 10993 and USP requirements for implants/contacts
Representative Specs & Lead Times
| Item | Typical Lead Time | Notes |
|---|---|---|
| Unfilled commodity resin | Available off‑the‑shelf | Short lead times |
| Glass‑filled engineering resin | 1–4 weeks (supply dependent) | MOQ and drying requirements |
| High‑performance polymer (PEEK/PEI) | 2–6+ weeks | Longer lead times and higher cost |
| Custom color or masterbatch | 2–8 weeks | Depends on batch creation and approvals |
Representative Projects
Glass‑Filled PA66 Structural Bracket
Replaced machined metal with glass‑filled PA66, reduced weight by 45% and achieved required stiffness; implemented increased gate size and tool coating to manage wear.
PC/ABS Housing with UV‑Stable Coating
Consumer electronics housing using PC/ABS blend with post‑paint and soft‑touch coating; designed draft and texture for consistent finish.
