SOLIDWORKS DFMXpress – Mill Rules Overview

Are your manufacturability issues bringing down your profits?

If yes, then look no further. DFMXpress, an integrated feature in SolidWorks is engineered to guide the designer on the problems faced during the manufacturing process. It automates the design process through a set of rules-based checks thereby accelerating and improving the entire design through manufacturability procedure.

In our earlier article we discussed on the drilled hole checks functionality in DFMXpress. In this, we shall explain you in detail on the Mill rules.

MILL RULES

1. DEEP POCKETS AND SLOTS

Deep, narrow slots are difficult to machine. The long, slender end mills required to machine them are prone to chatter, which makes tighter tolerances difficult to achieve. Deep slots also make chip removal more difficult if the slot is blind.

Recommendations:

• Avoid long corners with long radii.
• Design milled areas so that the end mill length-to-diameter ratio is no greater than 3:1.

2. INACCESSIBLE FEATURES

Features should be easily accessible for machining in the required direction. Inaccessible features require special cutters or machining techniques.

3. SHARP INTERNAL CORNERS

Sharp inside corners cannot be achieved with traditional milling and require non-traditional machining processes such as electrical discharge machining (EDM).

Recommendations:

• When designing a three-edge inside corner, one of the inside edges must have the radius of the end mill. A generous corner radius can accommodate a larger milling cutter, which is preferred. Use the radii recommended by fabrication personnel to ensure that tools are easily obtained and maintained.
• If sharp corners cannot be avoided, drill a separate relief hole to allow a male ninety-degree corner to fit. Drill the hole first because drills cannot withstand significant side loading.

4. FILLETS ON OUTSIDE EDGES

For outside corners, chamfers are preferred to fillets. An outside fillet requires a form-relieved cutter and a precise setup, both of which are expensive. Blending of fillets into existing surfaces is expensive to manufacture, even with ball end mill.

Team EGS

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