DFM for CNC Machining Checklist

Design for least effort
   

1. Tolerance

Design to ISO 2768 medium standard

1. Geometry

Remove as little material as possible

Use 2 setups if possible

Have two side surfaces parallel to each other

2. Material Suggestion

The following are easiest material for this category.

Plastic, use Delrin

Soft Metal, use 6061 Aluminum

Hard Metal, use 1018 Steel

3. Surface

Specify the surface roughness of 63 Ra.

Only define the intrinsic fillets

Specify “de-burr” all edges for external edges in the drawing

 

More Effort Design

1. Tolerance

Limit the tight tolerance only to the critical dimensions

2. Geometry

Simplify geometry to avoid 5-axis machining if possible

Limit the number of faces in order to limit set up

3. Select proper material to meet the design requirements

Maximum Effort Design

 

1. Define tight tolerance only for critical dimensions
2. Select standard tool sizes
3. Minimize the cut depth
4. For large parts, break into assemblies to reduce machining effort
5. Design parts with existing stock material
6. For small parts, minimize the cut depth if possible
7. Edges significantly increase the deburring efforts
8. Designs that require 5-axis CNC machining will significantly increase the machining time