Rotary Swaging

Rotary swaging is a very fast metal forming process, eg. 4-6 parts per minute. In addition to the speed of manufacture, the swaging process itself improves the mechanical strength properties of the work piece due to the work hardening phenomenon. Improved strength properties allow one to form very thin walled tubes, or to use a work piece material of a lower hardness classification (less expensive material). This would not be possible with conventional metal cutting operations. Rotary swaging can be applied up to a work piece length of some 1000 mm.

Part manufacturing by rotary swaging has another key benefit, namely weight optimization combined with forming of internal geometries. Since the material volume of the workpiece remains constant, a reduction of the outside diameter of a solid bar would lead to an increased length of the same workpiece. In the case of a drive shaft for a passenger car made of a solid bar, 20% material savings can be obtained by rotary swaging compared to traditional metal cutting techniques. 

In most cases rotary swaging works on the basis of a tube material that is hammered down to a specific diameter. However, the swaging process actually allows the manufacturer to vary the wall thickness of the tube material to match certain requirements for weight distribution and strength. In that context it is also important to stress that the swaging process allows one to form internal splines or other geometries with net shape accuracy (i.e quality IT7, and sometimes IT6 would be obtainable).

A third key benefit of rotary swaging is the excellent surface quality, and is directly comparable with a ground surface. More specifically, a surface roughness of Ra 0.1-0.3 can be obtained for internal geometries, and on outer surfaces for recess swaging Ra 0.6-1.0 can be guaranteed.

A fourth benefit that certainly shall not be neglected is the very long and reliable service life of the swaging tools. As a rule of thumb, the tools do not wear out but crack, which means that only good parts are swaged until tool breakage. Another rule of thumb is that swaging tools made of tungsten carbide have a 4-5 times longer service life than tools made of tool steel. So for large production series, carbide tools should be applied.

Put in short: Rotary swaging offers a fast, reliable, and cost effective manufacturing process that also saves weight of the final part without giving in on requirements as strength, functionality or quality.