Milling is typically used to produce parts that are not axially symmetric and DFM guidelines recommend avoiding sharp internal corners inside pockets when it is to be manufactured using milling process. Read the guidebook for important design rules such as Deep Radiused Corners, Sharp Internal Corners, Tool Accessibility, Narrow Regions in Pockets, Side and Bottom Radius, Tool Clearance Check and Angular Milling Faces. To subscribe to Guidebook, please visit http://dfmpro.geometricglobal.com/dfm-guidebook/