plastic gear Technical Overview

Common Plastic Gear Materials and Their Applications

Material selection is the single most important decision in plastic gear design. UNITECH-GEAR provides this comprehensive guide:

POM — Polyoxymethylene (Acetal)

The industry workhorse. Excellent fatigue resistance, low friction coefficient (0.2-0.3 dry), good dimensional stability, and very low moisture absorption (0.2%). Available as homopolymer (Delrin®) and copolymer grades. Best for: General-purpose gears, cams, bearings, automotive actuators. Temperature range: -40°C to 100°C continuous. Limitations: Poor UV resistance, attacked by strong acids.

PA6 / PA66 — Nylon

High strength and toughness. Excellent wear resistance and fatigue strength. Glass-fiber reinforced grades (PA6+GF15%, PA66+GF30%, PA66+GF50%) dramatically improve strength and stiffness. Best for: High-load gears, power tool gears, automotive under-hood applications. Temperature range: -40°C to 120°C (PA66). Limitations: Moisture absorption (up to 2.5% at saturation for unfilled) causes dimensional changes and property shifts. Not recommended for precision applications with wide humidity variation unless GF-reinforced.

PBT — Polybutylene Terephthalate

Good all-around performer. Excellent dimensional stability, low moisture absorption (0.1%), good electrical insulation properties. Often glass-fiber reinforced (PBT+GF20%, PBT+GF30%). Best for: Automotive electrical components, appliance gears, sensor housings. Temperature range: -40°C to 120°C. Limitations: Lower fatigue resistance than POM, notch sensitive.

PEEK — Polyether Ether Ketone

Premium high-performance material. Exceptional strength (tensile 100 MPa+), temperature resistance (260°C continuous), chemical resistance, and wear properties. Best for: Aerospace, medical implants, semiconductor equipment, oil & gas — applications where failure is not an option. Temperature range: -60°C to 260°C. Limitations: High material cost ($80-120/kg vs. $3-8/kg for POM), requires high mold temperatures (160-190°C), more challenging to process.

TPE / TPU — Thermoplastic Elastomers

Flexible and forgiving. Used for flexible gears, damping elements, and overmolded grip surfaces on gear knobs. Best for: Low-load flexible couplings, noise-isolating gear mounts, soft-touch surfaces. Limitations: Very low load capacity, high friction, poor dimensional stability for precision applications.

Material Selection Framework

Consider these factors in order: (1) Mechanical requirements — load, speed, duty cycle, (2) Environmental conditions — temperature, humidity, chemical exposure, UV, (3) Precision requirements — tolerance, backlash, transmission accuracy, (4) Regulatory — FDA, medical grade, UL, automotive specs, (5) Cost targets — material cost, processing cost, tooling amortization. UNITECH-GEAR engineers help evaluate trade-offs for each unique application.