Complete System Consisting of Dosing Machine and Mold Carrier Press
Truck Steps Produced by In-Mold Coating
Hennecke GmbH & Co. KG in Sankt Augustin, Germany, and Indupol International nv, in Arendonk, Belgium, worked together designing a plant to manufacture steps from rigid polyurethane (PU) foam with varnished surfaces for truck driver cabs.
A particular challenge was the mold geometry of the 3-D cavity, making it difficult to fill the mold with the PU material. BASF SE in Ludwigshafen supplied the raw material, while Bomix Chemie GmbH in Telgte, both Germany, provided the varnish and the release agent. Together with these two companies, several test series were conducted to find the best suited production process. This involves the reactive mixture filling the cavity reliably when fed into the closed mold. Immediately after curing, the varnish is applied by in-mold coating.
Several tests were carried out on sample components. After that, the truck producer finally gave the go-ahead for serial production. Machine and plant producer Hennecke supplied the high-pressure Topline HK dosing machine, the IBC container station and the mold carrier press as a complete solution. The mold carrier press was provided by AutoRIM Ltd. in Derbyshire, England.
The mold of the truck manufacturer is designed as a dual cavity so that both sides, i. e. the driver’s and passenger’s, can be manufactured in one cycle period. Due to the complex geometry and due to the design with grained surface, the mold is equipped with hydraulic extractor rods to facilitate demolding. A type MT18-2 transfer mixing head safeguards good mixing quality and raw material efficiency. The high-pressure PU dosing machine, HK 470/470, supplies the reaction mixture. The machine is designed for a maximum output of 940 cm³ of mixture per second. A mold carrier from the MG series opens and closes the mold. The press is designed to handle molds up to 2 t in weight. Industrial safety systems with laser scanners and light curtains guarantee the necessary labor safety. When opening, upper and lower mold plates pivot towards the operator, making it easier to remove components.
Cycle time is 5 min, approximately. This comprises 4 s shot time and 120 s for curing of the PU mixture. Subsequent application of varnish takes approx. 2 min, until final curing.
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