Nylon (PA) Injection Molding - A Comprehensive Guide

Nylon (PA) Molding Guide

Nylon (polyamide) is one of the most important engineering thermoplastics, widely used in Chinese injection molding for automotive, industrial, and consumer applications. This guide covers the key considerations for sourcing nylon parts from China.

Nylon Types and Applications

PA6 (Nylon 6): most common general-purpose nylon. Good balance of strength, stiffness, and cost. Applications: gears, bearings, housings. PA66 (Nylon 66): higher thermal and mechanical properties than PA6. Used for higher-temperature automotive applications. PA12 (Nylon 12): excellent chemical resistance, low moisture absorption. Used for fuel lines, medical tubing. PA6/6T, PA9T, PA46: high-temperature nylons for automotive under-hood applications. Glass-fiber reinforced (PA6-GF30, PA66-GF30): most common engineered compound.

Critical Processing Factors

Nylon is hygroscopic (absorbs moisture from air). Proper drying is critical: 80-120C for 2-4 hours depending on grade. Undried nylon causes splay marks, brittleness, and dimensional variation. Chinese factories should have desiccant dryers for nylon processing. Mold temperature: 80-120C (higher for glass-filled grades). Moisture content should be below 0.2% before molding.

Buyer's Tip: Nylon absorbs moisture after molding, which causes dimensional changes. A nylon part that measures perfectly at the factory may change by 0.2-0.5% after shipping due to moisture absorption. For precision nylon parts, specify: (1) Condition (as-molded or moisture-conditioned) for inspection, (2) The target moisture content for your application, (3) Dimensional tolerances at the conditioned state. Nylon parts in humid environments will be larger than dry parts.

What This Means for Your Project: Nylon molding from China is cost-effective (40-60% savings vs US) but requires careful moisture management. For precision applications, plan for post-mold conditioning (48 hours at 23C, 50% RH) before dimensional inspection. Glass-filled nylon wears molds faster - expect 25-50% shorter mold life for GF-nylon compared to unfilled.

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