General Comments on Process Technology

Both the rotary swaging and the axial forming processes are chipless. This means that forming of the part is done by moving (as opposed to removing) the material. The mechanical properties are improved due to the work hardening created by the forming processes.

Rotary swaging is a very fast hammering process, where a given tube diameter is swaged down to a specified geometry. The typical in-feed speed is 20 mm/second, and a part reduction can be as large as 85% obtained over a number of forming steps. In addition to the impressive cross section reduction and recess swaging, the swaging process also allows the forming of non-circular geometries like triangles, hexagons, ball shapes, longitudinal ball splines etc. A good rule of thumb for the part tolerance from rotary swaging would be IT8 for recess swaging and IT9 for feed swaging on the external part diameter. For internal swaging IT7 can be guaranteed.

Felss has developed a special and patent protected low frequency modulated axial forming process for chipless manufacturing of high quality internal and external splines. The splines are formed in small incremental steps - best understood as an integrated cold forward extrusion and calibration process. The spline forming process is valid on both solid parts and even very thin walled tubes. The highest precision and repeatability can be obtained with this special forming process. To be more specific, one can expect formed spline profiles to match DIN standard IT5 (DIN3962). The axial forming process itself allows a forming speed of 10-15 mm/second.

Increasingly, the two processes of rotary swaging and axial forming are combined: Hammering followed by axial forming. The latest development is the axial forming integrated with a threading operation.

The key benefits for the user can be summarised as follows:

• Higher precision,
• Reduced weight
• Increased strength properties, and
• Improved resource utilization, and
• More economical / cost effective manufacturing processes