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ISO 29988-1:2019 — Plastics — Polyoxymethylene (POM) Moulding and Extrusion Materials — Part 1: Designation System
Standard designation system for POM homopolymer and copolymer materials | Data block structure | Tensile modulus and MFR classification
1. Designation System for Polyoxymethylene Materials
ISO 29988-1:2019 establishes a system of designation for polyoxymethylene (POM) thermoplastic materials, including both homopolymers and copolymers (commonly known as acetal or polyacetal). The designation system provides a standardized data block structure that enables material specification based on characteristic properties such as tensile modulus and melt mass-flow rate (MFR), filler/reinforcement type and content, and intended application or processing method.
Why Designation Matters: A standardized designation system ensures that POM materials with identical property profiles can be sourced from different manufacturers with predictable performance. This is essential for global supply chains where material substitution must not require re-qualification of injection moulding tools.
2. Data Block Structure
The designation consists of four data blocks. The first block identifies the material type (POM-H for homopolymer, POM-C for copolymer). The second block specifies the tensile modulus in MPa (e.g., 2800 for a standard grade). The third block indicates the MFR in g/10 min. The fourth block provides supplementary information about additives, fillers, or special characteristics.
| Block | Position | Example | Description |
|---|---|---|---|
| Block 1 | Material type | POM-C | Copolymer polyoxymethylene |
| Block 2 | Tensile modulus | 2800 | Tensile modulus in MPa |
| Block 3 | Melt flow rate | MFR 09 | MFR = 9 g/10 min |
| Block 4 | Additives | GF20 | 20 % glass fiber reinforced |
Common Pitfall: Specifying only the trade name without the ISO 29988-1 designation can lead to procurement of functionally different materials. Always include the full data block string in purchasing specifications.
3. Relation to Material Specifications
The designation system serves as the basis for material specifications. By referencing the ISO 29988-1 designation, a product designer communicates the minimum required mechanical and rheological properties without over-constraining the supplier selection. This is particularly important for POM materials used in precision engineering applications such as gears, bearings, and fluid handling components, where consistent melt flow and modulus are critical for part dimensional stability.
4. Frequently Asked Questions
Q1: What is the difference between POM-H and POM-C?
A: POM-H (homopolymer) offers higher crystallinity and stiffness but lower thermal stability. POM-C (copolymer) provides better processing stability and chemical resistance.
A: POM-H (homopolymer) offers higher crystallinity and stiffness but lower thermal stability. POM-C (copolymer) provides better processing stability and chemical resistance.
Q2: How is tensile modulus measured for designation?
A: Per ISO 527-2 on injection-molded specimens conditioned at 23 °C / 50 % RH for 48 hours.
A: Per ISO 527-2 on injection-molded specimens conditioned at 23 °C / 50 % RH for 48 hours.
Q3: Can recycled POM materials use this designation?
A: Yes, with appropriate modifiers indicating recycled content. The designation system is material-property based, not source-restricted.
A: Yes, with appropriate modifiers indicating recycled content. The designation system is material-property based, not source-restricted.
Q4: Does the designation cover color?
A: Color is not directly coded but can be specified in supplementary information. Mechanical properties of colored grades should be verified separately.
A: Color is not directly coded but can be specified in supplementary information. Mechanical properties of colored grades should be verified separately.
