Maple in improved Quality of Cold Forged Shafts 

MAPLE is a quality driven company.1, by a quality policy which is clearly communicated inside Maple to all employees as well as by excellent quality KPIs. It is also documented by continuously rising the state of the art in quality technology which is applied in Maple production.

Cold forged shafts which are used in transmission, powertrain and hybrid or electric drive applications can exhibit different types of defects on the surface of the shaft. These can be closed or open cracks, they can be long and continuous or short, interrupted or located on edges, or even still exist on machined surfaces. Common to all these cracks is that they are non- systematic quality defects, appearing at a rate of a few per ten thousand or in even lesser incidents. The reason for these cracks is the deformation of the material in a tensile stress regimen. However, the cracks only form if one of the following three conditions exists: 1) A surface fold introduced by hot rolling of the bar, but so small that it could not be detected by eddy current testing in the steel mill 2) a segregation in the steel which leads to some brittle material structure even after proper heat treatment for cold forging or 3) a bigger inclusion near the surface which reduces the ductility of the steel. Condition 2) and 3) can not be detected by economical non-destructive testing.

Consequently, 100% visual check by skilled labour is undertaken on these types of cold forgings. Neither skills nor optimum working conditions, however, can typically completely prevent that some defective parts slip through the quality check. In order to increase the quality level, Maple has decided to apply automatic surface checks. The  plant has undertaken a project in which different methods of surface testing have been analysed. The combination of Laser-Profilometer and camera has proven to be able to detect all relevant surface defects, so this technology has been chosen for the quality check of these parts starting

With this investment, Maple demonstrates its willingness to invest into the highest quality technology in order to become the market leader for forged components in China.