The success of your injection part begins with choosing the right plastic, even before the mold. The wrong material = a part that breaks, flexes, wears out or is needlessly expensive. This guide compares the five main thermoplastics MARG works with — ABS, PP, PE, POM, PA — by function and answers the question “which one for which part.”

Quick Decision Table

MaterialStrengthBest-suited partWatch out
ABSRigid, dimensionally stable, good surface, economicalBox/enclosure, panel, cover, general structuralWeak in UV/outdoor
PPFlexible, fatigue- and chemical-resistant, hingeLidded boxes, living hinge, containers, automotiveLess rigid, hard to bond/paint
PEChemical resistance, low friction, toughSealed containers, bumpers, low-load partsLow rigidity, hard to bond
POMHigh rigidity, low friction, precise dimensionsGears, bearings, clips, sliding mechanismsExpensive, hard to bond, heat-sensitive
PA (nylon)Tough, wear- and temperature-resistantGears, load-bearing parts, wearing componentsAbsorbs moisture (dimensions shift); abrasive if filled

Selection by Function

Box, enclosure, cover → ABS (or PC)

Requires rigidity, dimensional stability and a good surface. ABS is economical and ideal; if impact/temperature is critical, PC (polycarbonate) or ABS+PC. (See Electronic Box/Enclosure Mold.)

Flexible, hinged, chemically exposed → PP

A living hinge (single-piece hinge) is practically made only with PP/PE. Chemical containers and lids that open and close repeatedly are PP’s domain.

Precision mechanical: gears, bearings, clips → POM

When low friction and dimensional stability are required, POM (acetal) is preferred. It runs without lubrication in sliding/rotating parts.

Wearing, load-bearing, heating up → PA (nylon)

Gears, cams, load-bearing components. Moisture absorption affects dimensions; this is taken into account with tight tolerances. Glass-fiber reinforced PA is very durable but abrasive → it reduces aluminum mold life (steel may be needed).

The Material + Mold Relationship (a critical point)

Material selection directly affects the mold type:

  • Unfilled/non-abrasive (ABS, PP, PE, POM) → an aluminum mold is economical and fast.
  • Glass-fiber/filled/high-temperature (e.g. PA6+GF30) → abrasive; a steel mold is generally required.

That is why we evaluate material and quantity together — and we tell you transparently which mold is the right one (aluminum or steel).

Not Sure?

Tell us where, under what load and in what environment the part will operate — let’s select the material by function together. If you don’t have a design, we do the design too.

Let’s Choose the Right Material for Your Part

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Frequently Asked Questions

Which plastic should I choose for my injection part?
It depends on the part’s function: ABS for boxes/enclosures and general structural parts; PP if chemical resistance, flexibility or a living hinge is needed; POM for wearing mechanical parts such as gears/bearings; PA (nylon) if impact/wear resistance and high temperature are needed. If you’re not sure, send us the part and we’ll select the material by function together.
What is the difference between ABS and PP?
ABS is harder and more dimensionally stable, easy to machine and has a good surface — ideal for parts such as boxes, enclosures and panels. PP is more flexible and fatigue-resistant, more resistant to chemicals and moisture, and living-hinge parts can be made from it; however, it is less rigid and hard to bond/paint.
When is POM (acetal/Delrin) used?
POM offers high rigidity, low friction and excellent dimensional stability; it is ideal for precise mechanical parts such as gears, bearings, sliding mechanisms and clips. It is more expensive, hard to bond, and degrades if overheated — so process control is important.
Can I use a glass-fiber reinforced (filled) material?
Yes, but carefully: glass-fiber reinforcement (e.g. PA6+GF30) increases strength and temperature resistance but is abrasive and seriously reduces aluminum mold life (down to a few thousand shots). For filled/abrasive materials, a steel mold is generally recommended; we advise you transparently based on quantity and material.