ABS PC Nylon POM Injection Molding China | Guide

Quick Material Selector

Before opening a tool, answer the question the part actually poses. The table below maps a common requirement to a starting resin. It is a triage, not a substitute for a grade-specific check — use it to open the conversation, then confirm with the deep dives and the decision path.

If your part must…	Start with	Watch out for
Be transparent and impact-resistant	PC	Chemical stress cracking
Be low-cost, opaque, easy to mold and paint	ABS	Lower heat resistance
Absorb impact, flex fatigue or wear, tolerate some moisture	Nylon (PA)	Moisture-driven size change
Hold tight dimensions, run low-friction, resist creep	POM	Higher, anisotropic shrinkage
Combine stiffness with dimensional stability	Glass-filled PA or POM	Warpage and mold abrasion

Choose by Function, Not by Name

The most common material mistake is picking a resin because it is familiar — "we always use ABS" — and then fighting the part through production. Resin choice should follow the job: what load the part sees, what temperature it lives in, whether it must be clear, whether it slides against something, and how tightly it must hold dimension. A housing, a gear and a transparent cover are three different problems even if they are all "plastic."

Once the function is clear, the order of decisions is consistent: material family → specific grade → part geometry and tolerance → mold and gate design → process and quality plan. Getting the family right early avoids a late tooling change, which is where most cost and delay hide. The deeper sections of this page walk that chain for each of the four resins.

The Four Resins at a Glance

These four cover the large majority of engineering-plastic injection molding outside of specialty polymers. They split into two behavioural groups — amorphous (ABS, PC) and semi-crystalline (Nylon, POM) — and that split, more than the name, drives shrinkage, warpage and mold design.

Resin	Class	Typical use	Planning shrinkage	Key trade-off
ABS	Amorphous	Enclosures, housings, trims	~0.5–0.7%	Cheap and easy; not clear, modest heat
PC	Amorphous	Covers, lenses, shields	~0.5–0.7%	Clear and tough; stress-crack prone
Nylon (PA6/PA66)	Semi-crystalline	Gears, clips, wear parts	~1.0–2.0%	Tough and fatigue-resistant; moisture
POM (Acetal)	Semi-crystalline	Precision gears, bushings	~1.8–3.0%	Stable and low-friction; high shrink

How to Read a Material Spec: Material → Grade → Application

A useful specification names three things, in this order:

On the drawing and purchase order, write the grade, not just the family. "ABS" on a PO leaves the molder free to substitute a grade with different shrinkage or heat performance — and the part may not fit. A controlled grade with lot traceability is what keeps the second order identical to the first.

ABS: When It Earns Its Place

Acrylonitrile butadiene styrene is the default engineering plastic for a reason: it is easy to mold, dimensionally predictable, takes paint and texture well, and is inexpensive. It pairs good stiffness with decent impact and a smooth surface that suits consumer and industrial enclosures.

Where it fits. Indoor housings, appliance and electronics bodies, trims and brackets where cost and surface finish lead. Where it struggles. Continuous outdoor UV without stabilization, high heat, and contact with some solvents and strong chemicals. It is opaque, so it cannot serve a transparent requirement. For a deeper ABS-specific dive, see our custom ABS plastic molding page.

Polycarbonate (PC): Clarity, Impact and Heat

Polycarbonate is the choice when a part must be transparent and tough, or when it must survive higher heat than ABS allows. Its impact strength is exceptional, and it holds shape at temperatures where ABS would soften. That combination puts it in covers, lenses, guards and transparent shields.

Where it fits. Transparent or tinted parts needing impact and heat resistance. Where it struggles. PC is prone to stress cracking when exposed to certain chemicals and to high sustained stress at gate or boss areas; it is also very hygroscopic and must be dried thoroughly. UV-stabilized grades handle outdoor use. Do not assume a generic "PC" is flame-rated — that requires a specific FR grade documented by UL94.

Nylon (PA): Toughness, Moisture and Friction

Nylon — polyamide, usually PA6 or PA66 — is the workhorse for parts that move or take repeated load. It absorbs impact, resists fatigue and wears well against metal and itself, which is why it appears in gears, clips, cable ties and bearing surfaces.

The moisture caveat. Nylon absorbs water from the air. As it conditions, dimensions grow slightly and impact rises while stiffness falls. For tight-tolerance parts, design against the conditioned state and confirm the critical dimension method with the molder. The shrinkage caveat. PA shrinkage is higher and more variable than ABS/PC; glass filling improves dimensional stability but increases warpage and mould abrasion, so the tool needs hardened steel.

Acetal (POM): Precision, Low Friction, Creep Resistance

POM, commonly called acetal or Delrin-style resin, is the precision player. It holds dimension tightly, slides with very low friction, resists creep under load and shrugs off many fuels and solvents. That makes it the natural choice for small gears, bushings, zipper components and valve parts.

Where it fits. Precision, low-wear, tight-tolerance motion parts. Where it struggles. POM shrinkage is the highest of the four and somewhat anisotropic, so the mold and gate must be designed for it; it is also not a good outdoor UV performer without stabilization. Compared with nylon, POM wins on dimensional stability and friction; nylon wins on impact and cost.

ABS vs PC: Which One?

Both are amorphous and mould predictably, so the decision is usually about clarity, heat and chemical environment rather than moulding difficulty. If a part is clear, PC (or a clear blend). If it is a painted housing, ABS.

ABS vs Nylon

This is a stiffness-versus-toughness-and-wear trade. ABS is the better "structure" material; nylon is the better "moving or loaded" material. The moisture and shrinkage behaviour of nylon is the main reason teams stay on ABS until the application forces the change.

PC vs Nylon

These two rarely compete directly because one is clear-and-stiff and the other is opaque-and-tough. When both could work, the deciding factors are usually clarity (PC) versus wear and fatigue life (nylon).

Nylon vs POM

Both are semi-crystalline engineering plastics, so they share moisture sensitivity and mould-design care. The split is precision-and-friction (POM) versus toughness-and-cost (nylon). Small precision gears and bushings tend to land on POM; larger loaded or impact parts tend to land on nylon.

Amorphous vs Semi-Crystalline — and What It Means for Molding

This split explains more moulding behaviour than any single number. Amorphous resins (ABS, PC) cool without forming a sharp crystal structure: lower, more uniform shrinkage, less warpage, better dimensional stability, but often lower chemical and temperature resistance at the high end. Semi-crystalline resins (PA, POM) form crystals as they solidify: higher and more directional shrinkage, more warpage risk, but better wear, creep and chemical resistance.

Modified and Glass-Filled Grades

Most production parts use a modified grade, not a neat resin:

Every modifier shifts moulding behaviour — shrinkage, flow, warpage, abrasion — so the grade, not the family, is what the tool is designed around.

Drying and Moisture Control

Moisture in the pellet turns into steam at melt temperature: splay marks, bubbles, surface defects, and — for PC and nylon — hydrolysis that actually cuts the molecular chain and weakens the part. Drying is not optional for these resins.

Resin	Drying need	Why it matters
PC	High	Very hygroscopic; hydrolysis weakens the melt
Nylon (PA)	High	Very hygroscopic; also affects as-molded dimensions
ABS	Moderate	Some moisture; splay if skipped
POM	Lower	Less hygroscopic, but store per spec

Material-Specific Molding DFM

Good plastic DFM starts from the resin's shrinkage and flow, not just the shape:

For a broader molding capability view, see our injection molding services and injection mold making in China.

Mold and Tooling Setup

The mold is where resin behaviour becomes part geometry. Key choices:

Element	What it controls	Note for these resins
Steel	Life, finish, abrasion resistance	Glass-filled grades need hardened steel (e.g. through-hardened or H13)
Gate type	Flow, weld lines, stress	Pin, fan, submarine or hot-tip; pick for part shape and cosmetics
Runner	Scrap, cycle, balance	Hot runners cut waste for volume; cold runners suit lower runs
Cooling	Cycle, warpage	Uniform cooling is critical for semi-crystalline shrinkage control
Surface	Appearance, release	Textured faces need more draft; SPI finishes set the look

Multi-cavity and family molds are common for these resins; balancing fill across cavities is part of the tooling quote, not an afterthought.

Quality, Traceability and Substitution Control

This is where "which plastic" becomes "which part, consistently." Three controls matter to a buyer:

From RFQ to First Article: How a China Partner Runs It

A clean molding program follows a predictable path. Knowing it helps you write a better RFQ and avoid surprises:

RFQ checklist. 3D model (STEP/IGES) and 2D drawing · target resin family or a function description · annual and per-order quantity · critical dimensions and tolerances · surface finish and texture · regulatory or compliance needs · target market. Send it through the form and we will return a material + DFM review with the quotation.

Send Your RFQ & Material Spec

Real Cases

Which Material? A Decision Path

Use this path as a fast filter, then confirm against the deep dives and the RFQ review. It favours the simplest resin that meets the function.

Frequently Asked Questions

Not Sure Which Resin Fits Your Part?

Send the drawing and tell us what the part must do — load, temperature, clarity, wear and compliance. Our engineering team will recommend a grade, run a DFM review and return findings with your quotation.

Get a Material & DFM Review Or explore injection molding services →

Material and DFM feedback is returned with the quote — typically within one business day for standard parts.

Xiamen Goldcattle Plastic & Metal Products Co., Ltd. — injection molding, mold making, CNC machining, 3D printing, die casting and sheet metal fabrication performed in-house under one ISO 9001:2015 quality system, with AS9100-aligned and ISO 13485-aligned process controls and material certificates available on request. Founded in 1998.