Special combination of metals or unique alloys is called for.
Competitive situation necessitates reduction in or elimination of machining or scrap losses.
Precise dimensions and tolerances must be maintained with consistent reproducibility over large volumes. Where good surfaces are required without grinding. Need for built-in self lubricating capability as provided by oil impregnation. Need for controlled physical properties, such as degree of porosity or density, hardness, tensile and impact strength, ductility, wear resistance, etc.