Manufacturing truck steps using the in-mould-coating process

The supply company Indupol has been mass producing steps for trucks since October 2014. As inconspicuous as the polyurethane part may look, it posed a real challenge for the developers at Hennecke due to its complex geometry.

###4782###

Indupol, a supplier for truck and bus manufacturers from Arendonk, Belgium, looked for a suitable partner for systems for manufacturing steps from rigid polyurethane foam with a painted surface for truck driver cabs. After asking the Sankt Augustin-based German PU processing machinery and equipment manufacturer Hennecke, they soon received the first sample parts. According to Hennecke, the challenge with this project was the extreme mould geometry of the 3D cavity, which made filling the mould with polyurethane considerably more difficult. Together with BASF as supplier of the easily foaming PU material and Bomix, who contributed the paint and release agents, Hennecke was able to find a suitable solution in several series of tests carried out at its technical centre whereby the reactive mixture fills the cavity reliably when being poured into the closed mould. Immediately after curing, a layer of paint is applied in the in-mould-coating process.

After extensive testing of the sample parts, the truck manufacturer gave the go-ahead to Indupol for mass production. Hennecke supplied the required production line, a high-pressure Topline HK 470/470 polyurethane metering machine with IBC container station and a mould carrier press from Hennecke partner AutoRIM Ltd, Derbyshire, UK, as a complete solution. Indupol's mould 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 mould is equipped with hydraulic extractor rods for demoulding components more easily.

A highly efficient MT 18-2 deflection mixhead ensures optimal mixing quality and raw material efficiency. The high-pressure PU metering machine from Hennecke is designed for a maximum output of 940 cm³ of mixture per second. The mould is opened and closed by a mould carrier of the MG series from AutoRIM Ltd. The press is suitable for moulds of up to 2 t in weight. Security systems with safety laser scanners and light curtains provide protection for workers. When opening, the upper and lower mould plates pivot towards the operator, thus facilitating the removal of components. The cycle time is approximately 5 min. The period is divided into a shot time of 4 s and a curing time of 120 s for the PU mixture. The subsequent application of paint takes a total of approximately 2 min until curing.