processing | Temperature control
Switching to
conformal cooling of moulds can cut cycle times. In this article, Renishaw describes how additive
manufacturing of
mould cores helped its customer Alfred Kärcher
Conformal cooling with AM boosts moulding productivity
Main image: Alfred Kärcher has reduced mould cooling time in the production of yellow casings for its K2 model
The use of cores incorporating conformal cooling in the moulds for its plastic casings has allowed the injection moulding operation of Alfred Kärcher in Germany to reduce the cooling time for each part by 55%, giving a huge boost to the company’s moulding productivity. The special cores, which were designed by Renishaw, were produced using metal additive manufacturing technology. High-pressure washers from Kärcher, with their
unmistakable bright yellow casings, have become a permanent fixture in many German homes and are growing in international popularity. The devices’ power and reliability encourage people to use their “Kärcher” as part of their daily cleaning routine, both inside and outside the home. To meet the increasing demand from around the
world, Kärcher produces its compact washer by the million every year. More than two million K2 basic pressure washers
alone leave the Obersontheim factory every year. However, even this level of production is unable to meet the global demand.
Challenge to raise output One of the Kärcher washers’ most recognisable features is their bright yellow casings. This was also one of the key bottlenecks in the manufacturing
26 INJECTION WORLD | July/August 2017
process. For example, the casings for the K2 series washer are produced on six injection moulding machines, each capable of moulding 1,496 casings a day. This was not enough for Kärcher, which has four assembly lines, operating three shifts per day, to give a production capacity of 12,000 assembled and packed K2 high pressure washers each day. Clearly, one option would be to add more moulding machines. However, Leopold Hoffer, the coordinator for injection moulding at Kärcher’s Obersontheim factory, believed that it should be possible to generate more productivity from the existing equipment. “Our aim was to reduce the cycle time from the origi-
nal 52s to between 40 and 42s,” said Hoffer. He approached Pliezhausen-based LBC Engineering, which was acquired by Renishaw GmbH in May 2013, to work on improving the cooling time in the moulds.
Simulation and design “The first stage of the project was to obtain data for the existing moulds to determine whether Kärcher’s goal was feasible,” recalled Carlo Hüsken, who coordinated the project for Renishaw. The existing injection moulding process was mapped with thermographic images provided by Kärcher and simulated using Cadmould 3D-F simulation software.
www.injectionworld.com
PHOTO: GOGOLL
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