Casting Study: End Cap for a Pneumatic Door Closer

Alloy 3 was chosen as the end cap material because of the ease with which it is processed. Both material and tooling cost are minimized, and the product can be made with existing expertise and plant equipment. Alloy 3 castings can be produced with high dimensional accuracy. In this application, the tolerances between the end cap and other components are very tight, and Alloy 3 castings provide a reliable fit. Alloy 3 gives an excellent surface finish without the need for polishing. This is critical in this application because the casting surface must provide an air tight seal. The surface is also excellent for powder coating. Inside the cap are four lugs, and each is pressed down over an insert to form a permanent assembly. Alloy 3 has the ductility to achieve deform plastically and provide a reliable assembly obviating the need for fasteners.