VDI 3400 GRADE GUIDE · PHYSICAL COMPARISON
VDI 30 marks a more pronounced texture in common comparison charts. Before selecting it, check whether the detail, draft, and release conditions of the part can accommodate the requested finish.
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 30
Coarser finishes should be reviewed with the moldmaker for geometry, draft, and release considerations. VDI 30 is where texture starts to visibly affect mold release. Draft angle and ejector layout deserve a second look before this grade is locked into the tooling design.
Before you specify this grade
Ask the moldmaker to review draft and shutoff details for the actual geometry, then sign off against a physical master and molded sample.
- 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.
Has the tool design allowed for the selected texture and direction of draw?
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.
See VDI reference plaques View the complete VDI 12–45 guide
Reference and limitations
The VDI official catalog describes VDI 3400 as a guideline on electrical discharge machining. The Ra value here is reproduced as an indicative supplier comparison value, not represented as a certification or a complete statement of the licensed guideline. Published charts can vary in rounding. Agree the applicable reference and measurement procedure before contractual use.
Supplier information only. No VDI endorsement or certification is implied. Validate the selected finish on the actual tool and molded part.
Content last reviewed: 2026-09-24.