Fig.2 shows the layout of tools used for the surface densification of the development helical gear shown in Fig.1. Given the helical nature of the external form of the part, the upper (outer and inner) and lower outer punches follow a helical motion that is in keeping with the geometry of the gear (the punches rotate together as they advance axially). The lower inner punch remains stationary, as do the DensiForm® tools and die. This action is different from that seen at powder compaction where the die floats.