CNC design rules.
Machinable geometry.
Cost-optimal CNC.
CNC design fundamentals. Internal radii, pocket depth, hole sizes, tolerance, surface finish. Get DFM right and reduce CNC cost 30-50%.
Key principles.
Tool radius
All internal corners get tool radius. Larger radius = larger tool = faster cutting.
4-6× tool diameter
Limit pocket depth to 4-6× tool diameter. Beyond requires specialty tooling.
Common diameters
Use 3, 4, 5, 6, 8, 10, 12, 16, 20 mm tools. Custom tools costly.
0.5 mm minimum
Aluminum 0.5-0.8 mm. Steel 0.8-1 mm. Below — vibration issues.
±0.025 mm typical
Default ±0.1 mm general. Tight only where needed.
Ra 1.6 typical
As-machined Ra 1.6-3.2 µm. Polish Ra 0.4 µm. Mirror Ra 0.05 µm.
FAQ
Internal corner radius minimum?
Specify ≥ 1/3 pocket depth. For 15mm pocket: R5 minimum allows 10mm tool. Smaller forces specialty tooling.
Hole sizes?
Standard drill bits 0.5-25 mm in metric. Match drawing to standard sizes.
Tolerance specification?
Default ISO 2768-m or ±0.1 mm. Tighter ±0.025 only on critical features. Tight tolerance 5-10× cost.
Standard threads?
M3, M4, M5, M6, M8, M10 metric. UNC/UNF inch standards. Custom threads expensive.
Aluminum vs steel cost?
Aluminum machines 3-5× faster than steel. Material cost similar. Aluminum total cost lower.
Free DFM review?
Yes — quote includes DFM review at no cost. Identifies cost drivers, suggests improvements.
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