Design Guidelines: CNC Milling
Our basic guidelines for CNC milling include important design considerations to help improve part manufacturability, enhance cosmetic appearance, and reduce overall production time.
Maximum Dimensions (3-axis milling)
|10 in. x 7 in. x 3.75 in.|
|10 in. x 14 in. x 1.75 in.*|
|22 in. x 14 in. x 0.75 in.*|
|22 in. x 14 in. x 1.25 in.**|
|254mm x 177.8mm x 95.25mm|
|254mm x 356mm x 44mm*|
|559mm x 356mm x 19mm*|
|559mm x 356mm x 32mm**|
Maximum Dimensions (5-axis milling)
|2.6 in. x 2.9 in. x 3.9 in.|
|66mm x 73mm x 99mm|
|SIZE||0.25 in. x 0.25 in.|
|SIZE||6.35mm x 6.35mm|
Typically, Protolabs can hold a machining tolerance of +/- 0.005 in. (0.13mm). Part features are recommended to be thicker than 0.020 in. (0.51mm) in all regions and a nominal part thickness above 0.040 in. (1.02mm) is required. Maximum depth that can be milled is 2 in. (50.8mm) from either side of part. For specific milling dimensions by material, see maximum part extents for machining.
*These part sizes can only be milled from two sides, and in ABS, acetal, and aluminum 6061 and 7075.
**This part size can only be milled from two sides, and in Aluminum 6061.
5-Axis Milling Capabilities
We use 5-axis indexed milling—in addition 3-axis milling and turning—to machine parts. With 5-axis indexed milling (also referred to as 3+2 milling), two axes are stopped while the tool is engaged with the part. This allows for more complex geometries and non-orthogonal features like off-axis holes.
Better finishes are also possible on non-orthogonal surfaces and because 5-axis milling increases machining efficiencies, more cost-efficient parts can be had.
Typically, we break (debur) the edges on all machined parts. All machined plastic parts are left as-machined, which may leave visible tool marks. Some metal parts, on the other hand, allow more choice. Parts left with sharp edges should be handled with care.
|Edges broken with visible toolmarks|
||Edges broken with visible toolmarks, edges broken with light bead blast, or sharp edges with visible toolmarks|
|ALL OTHER METALS
||Edges broken with visible toolmarks or edges broken with light bead blast|
We currently support UNC and UNF threads from #2 up to 0.5 in., and metric threads from M2 to M12. Avoid modeling internal threads on your part design.
Sharp inside corners on a part will be radiused (rounded) as a natural result of the CNC machining process. Resulting radii will be identified on your quote.
Recommended text considerations for CNC milling:
Plastic and soft metals: Minimum width of 0.018 in. (0.457mm), depth of 0.0118 in. (0.3mm). Example text size would be 14 point Ariel Rounded MT font.
Hard metals: Minimum width of 0.033 in. (0.838mm) and depth of 0.0118 in. (0.3mm). Example text size would be 22 point Ariel Rounded MT font.
- If design permits it, opt for recessed text versus raised.
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