VDI 3400 GRADE GUIDE · PHYSICAL COMPARISON
VDI 42 is near the coarse end of the common 12–45 comparison progression. Use a physical sample to ensure the requested grain is intentional and compatible with the part's geometry.
Published grade on this site: VDI 42 · Indicative comparison value: Ra 12.5 µm
This Ra figure matches the widely published Charmilles/Agie-derived VDI 3400 comparison chart, cross-checked here against an independent EDM reference-standard supplier's published specification (see citations below), not only against this site's own material. It is an indicative comparison value, not a licensed-standard quotation, gloss measurement, texture-depth conversion, guaranteed molded appearance, or contractual tolerance. If another document (for example a downloadable PDF) shows a different rounded figure, treat this page as the controlling reference until confirmed otherwise with your supplier.
How to evaluate VDI 42
Coarser finishes should be reviewed with the moldmaker for geometry, draft, and release considerations. VDI 42 is coarse enough that mold filling and release become part of the appearance conversation, not only the tooling conversation. Loop in the moldmaker before this callout is finalized.
Before you specify this grade
Review transitions and release direction with tooling, and approve a molded trial on representative features before final specification.
- Mark exactly which faces receive the texture and note the direction of draw.
- Name the physical master and confirm its material and condition.
- Approve appearance on a molded sample using the production resin and color.
- Define the measurement method and acceptance limits if Ra is contractual.
Will this coarse texture remain acceptable at edges, ribs, shutoffs, and deep-draw areas?
Compare adjacent grades
Look at the reference plaques together rather than relying on a phone or monitor image. The physical plaque helps align design, tooling, purchasing, and inspection; a production-material trial remains necessary for final appearance approval.
Need the physical reference?
Review the available VDI reference plaques and confirm which scale or material version covers your target grade before ordering.