MATERIAL GUIDE
POM-C vs POM-H
Practical material knowledge for better sourcing decisions — written for industrial buyers, not polymer chemists.
TYPICAL REFERENCE VALUES FOR MATERIAL FAMILIES — EXACT VALUES DEPEND ON GRADE AND MANUFACTURER. GRADES AND SPECIFICATIONS ARE CONFIRMED WITH YOU BEFORE EVERY ORDER.
One Polymer, Two Versions
POM (acetal) is supplied in two versions: homopolymer (POM-H) and copolymer (POM-C). To a designer they look similar — stiff, low-friction, easy to machine — but the differences matter when you specify parts that must hold dimensions in hot water, chemicals, or precision mechanisms.
POM-H typically offers slightly higher tensile strength, stiffness and fatigue resistance, and better creep behavior at elevated temperature. POM-C sits marginally lower on raw mechanical numbers — a difference that is irrelevant in most machined applications but can matter in heavily loaded thin-wall parts.
EDGE · POM-H
POM-C is the more chemically robust of the two in continuous service, particularly in hot water and alkaline media, where copolymer grades degrade more slowly. For washdown environments and hot-water contact, POM-C is generally the safer specification.
EDGE · POM-C
POM-H stock shapes from some manufacturing routes can show centerline (core) porosity in larger diameters — small voids that appear on machined faces. POM-C is less prone to this. If your part machines away the center of a large-diameter rod, copolymer avoids a classic cosmetic and sealing problem.
EDGE · POM-C
Side-by-Side Comparison
| Property | POM-H (homopolymer) | POM-C (copolymer) |
|---|---|---|
| Tensile strength / stiffness | Slightly higher | High |
| Creep at elevated temp. | Better | Good |
| Hot-water / alkali stability | Good | Better |
| Centerline porosity risk | Higher (large rods) | Lower |
| General machinability | Excellent | Excellent |
Selection Guidance
DEFAULT TO POM-C WHEN
CONSIDER POM-H WHEN
BOTH ARE STOCKED. IF YOUR DRAWING JUST SAYS “POM”, WE WILL CONFIRM WHICH IS APPROPRIATE FOR THE APPLICATION.
Want a grade recommendation for your application?