Metal parts are increasingly replaced by plastic parts. In motor vehicle construction, it is particularly essential for the attachment points of the plastic parts to be stabilised by metal bushings. A possible procedure is to fit the bushings into the plastic parts by hot insertion or cold pressing later on. For the quality of the screw connection, it is important for the bushing to protrude a specified amount.

The automatic assembly machine made by HENKEL + ROTH, and exhibited on the MOTEK 2007 fair ensures bushing press-fit using a ball screw driven by a servomotor.

The bush press-fit positions may be programmed freely by servo axes in 4 degrees of freedom.

During press-fitting, the depth is measured by applying a low feeler force, and it is readjusted continuously in order to compensate the elastic deformation of the plastic part during the press-fit process. This regulated press-fit relies on the use of a process PLC with an adaptive position regulator. This enables the smart servo screw press to reduce the rejects rate.
The plant can be retooled for other part types with minimum effort, just by replacing the quick-release mounting.

Bushes are fed using a vibratory hopper conveyor. The separated bushes are preheated to a defined temperature in a belt furnace. Induction heating is possible on an optional basis.