End mills have cutting edges on both the end and sides, permitting end cutting and peripheral cutting. Select upsharp tools for faster speeds. Select radial edged tools for longer tool life. Select the largest shank diameter available that will work in your application to maximize rigidity and minimize axial deflection and chatter. Select fewer flutes for milling softer materials and higher feeds and speeds where more chip space is required or when machine horsepower is limited. Select more flutes for milling tougher materials at reduced feeds and speeds or for increased table feeds using the same cutting speeds. Select the largest practical diameter to maximize rigidity, minimize chatter and improve tool life. If machine spindle speed is limited, the largest practical diameter permits higher cutting speeds.