Why DFM matters
Smart design decisions can remove hours of machine time, simplify setups, and prevent rework. Below are field-tested tips we see move the needle most.
12 DFM tips
- Prefer neutral CAD: Send STEP (.step/.stp) or Parasolid (.x_t/.x_b). STL is OK for quoting but lacks true geometry.
- Call out only critical tolerances: Default general tolerance can be ±0.05 mm for metals (±0.10 mm plastics). Tighten only where function demands (e.g., fits, sealing).
- Add internal corner radii: Design pocket corners ≥ tool radius (e.g., 3/6/10 mm). Bigger radii = faster cutting, better surface, longer tool life.
- Keep walls robust: Metals ≥ 1.0 mm; plastics ≥ 1.5–2.0 mm. Very thin walls chatter and slow machining.
- Use standard hole sizes & depths: Choose common drills; keep depth ≤ 10×Ø when possible. For reamed/precision holes, mark them clearly.
- Threads: Prefer M3 and up (smaller is possible but riskier). Thread engagement ≈ 1–1.5×Ø is usually enough. Leave room for taps; add chamfers.
- Avoid ultra-deep narrow slots: If required, consider two-sided machining or redesign with reliefs to fit standard cutters.
- Break sharp edges: “Deburr & break edges 0.2–0.5 mm” reduces handling damage and inspection rejects.
- Plan finishes early: Anodize, bead blast, powder coat, or passivation can shift dimensions. Flag cosmetic faces and masking needs.
- Design for workholding: Provide flat clamping faces; avoid features that block jaws/vises. Add temporary tabs if necessary.
- Minimize setups: Symmetry and uniform Z-depths speed machining. Combine features to reduce re-clamping.
- Provide a clear drawing: Even with 3D, a PDF drawing for tolerances, threads, finish, and critical datums prevents ambiguity.
Quick checklist
- File: STEP/Parasolid + PDF drawing
- Tolerances: only where function needs it
- Radii/walls/holes: within guidelines above
- Finish: specified + masked faces identified
- Quantities & target lead time included in RFQ
CTA: Need a fast, manufacturable quote? Upload your STEP and drawing on our RFQ page.
FAQ
Q1: What’s a reasonable “standard” tolerance for prototypes?
A: ±0.05 mm for metals and ±0.10 mm for plastics is typical. We can hold ±0.01–0.02 mm on critical dimensions when requested.
Q2: Is STL enough for machining?
A: STL is fine for visualization/quotes, but please include STEP/Parasolid for true geometry and best accuracy.
Q3: How small can holes be?
A: We can go below Ø1.0 mm, but cost/lead time increase. Staying ≥ Ø1.0–1.5 mm with depth ≤ 10×Ø is more efficient.
Q4: Do you provide inspection reports?
A: Yes—standard inspection or full CMM report on request.
Q5: What thread depth should I call out?
A: Typically 1–1.5×Ø engagement suffices; deeper adds little strength but raises cost.
