Initial situation

Initial situation

There are two main requirements for an economic forging production: energy efficiency and material efficiency. Especially, since the material costs for forging of complex long pieces like crankshafts accounts for up to 50 % of the total production costs in forging.

In conventional forging, flash – the excess material – is used to achieve a complete filling of the die gravure. Also, it helps to direct surface defects of the preforms out of the part. There is almost no flash when forging simple geometries. For complicated geometries like crankshafts the excess material can sum up to 40 % of the raw material mass or more.

From a technical perspective, it is possible to forge crankshafts completely flashless, but for several reasons flashless forging cannot yet meet industrial needs, e. g. there is a high technological and monetary effort to develop and to produce the dies. Additionally, the utilized dies for flashless forging are closed forging dies, which are exposed to higher forming forces and stresses and therefore they have more wear and thus a shorter life time. Also Small- and Medium-sized Enterprises (SMEs) have little experience with this new technology.

 

Formin stages steering link

Fig. 1: Forming stages flash reduces crank shaft

 

Flash reduced forging (Fig. 1) of high duty parts provides high dimensional accuracy and high work piece qualities at reduced energy and material consumption. Flash reduced forging is much easier to realize for industrial application than flashless forging, although it is almost as effective. With regard to economical and environmental aspects, flash reduced forging offers several advantages:

   –  Because of the lower raw material weight the material consumption is reduced in comparison to a conventional process.
   –  Due to the material reduction the energy output is reduced as well.
   –  Because less material has to be produced and heated up.

Thus, flash reduced forging can be considered a reasonable alternative to conventional forging.