Manufacturing truck steps with Hennecke’s In-Mold-Coating process

Belgium-based automotive supplier Indupol turned to German polyurethane (PU) specialist Hennecke’s technology for producing truck and bus door steps.

The challenge with this project was the extreme mold geometry of the 3D cavity, which made filling the mold with PU considerably more difficult.

plastic processing machinery

Manufacturing truck steps with Hennecke’s In-Mold-Coating process

Together with BASF, a supplier for the easily foaming PU material, and BOMIX, who contributed with the relevant paint and release agents, Hennecke developed a solution in which the reactive mixture fills the cavity reliably when being poured into the closed mold.

Immediately after curing, a layer of paint is applied in the In-Mold-Coating process.

After extensive testing of the sample parts, the Belgium truck manufacturer, Arendonk, approved the solution for mass production.

Hennecke supplied the required production line, a high-pressure TOPLINE HK metering machine with IBC container station and a mold carrier press from Hennecke partner AutoRIM Ltd, as a complete solution.

Indupol’s mold is designed as a dual cavity so that the driver’s and passenger’s side can be manufactured in one cycle period. Due to the complex geometry and a design with a grained surface, the mold is equipped with hydraulic extractor rods for demolding components more easily.

An efficient MT 18-2 deflection mix head ensures optimal mixing quality and raw material efficiency. The high-pressure PU metering machine HK 470/470 supplies the reaction mixture, which is designed for a maximum output of 940cm³ of mixture per second.

The mold is opened and closed by a mold carrier of the MG series from AutoRIM. The press is for molds of up to two tons in weight. When opening, the upper and lower mold plates pivot towards the operator, thus facilitating the removal of components.

Cycle time is approximately five minutes. The period is divided into a shot time of 4s and a curing time of 120s for the PU mixture. The subsequent application of paint takes a total of approximately two minutes until curing.