Gate vestige — the small residual mark where the feedstock entered the mold cavity — is an unavoidable feature of injection-molded MIM parts. Its acceptable height depends on the gate type, part application, and whether the affected surface is cosmetic.
Typical gate vestige heights by gate type:| Gate Type | As-Molded Height | After Manual Trim | After Surface Finishing | Best For |
|---|---|---|---|---|
| Edge gate | 0.10-0.30 mm | 0.05-0.15 mm | 0.02-0.05 mm | General parts, non-cosmetic surfaces |
| Tunnel (submarine) gate | 0.05-0.15 mm | 0.03-0.10 mm (self-trimming during ejection) | 0.02-0.05 mm | Automated high-volume production |
| Tab gate | 0.15-0.40 mm | 0.08-0.20 mm | 0.03-0.08 mm | Thick-wall parts where strength is needed at gate |
| Fan gate | 0.08-0.20 mm | 0.05-0.12 mm | 0.02-0.05 mm | Thin-walled parts, even fill distribution |
| Pinpoint gate | 0.05-0.12 mm | 0.03-0.08 mm (sheared during ejection) | 0.01-0.05 mm | Cosmetically sensitive parts, small features |
Use a note like: "Gate vestige shall not exceed 0.10 mm above surrounding surface. Gate location per ATMIK DFM recommendation." This gives a measurable acceptance criterion.
Quick Q: How much gate vestige is acceptable on a MIM part?For non-cosmetic surfaces: 0.10-0.20 mm is standard and acceptable. For cosmetic surfaces requiring Class A finish: specify 0.05 mm maximum with gate location on a non-visible surface. The gate vestige can be further reduced by tumbling, polishing, or machining in a secondary operation.
For the lowest gate vestige, specify a tunnel (submarine) gate, which self-trims during ejection and leaves approximately 0.03-0.10 mm residual — no manual cutting needed.