At Progress-Werke Oberkirch, a subcontractor to the automobile industry, deep-drawn parts are manufactured from carbon or galvanized steels. A problem arose on 2 Müller-Weingarten presses in which the cooling lubricant emulsion had to be changed every week due to the increased concentration of foreign oils and fine contamination. In addition, employees were suffering from skin irritations. A belt filter which was already in use on the installation did not improve cleaning performance adequately. A water-miscible cooling lubricant (emulsion, added in a quantity of 8 – 12 %) is used at a temperature of 30° C, the volume is about 1,000 l. The emulsion is contaminated with hydraulic oil, belt greasing oil and fine abrasion particles.
Solution / Realization
STA installed a combination bath maintenance system, which consisted of an NZ-50 centrifuge separator and a DPS-350 oil separator in the bypass on the belt filter. The feed pump uses a surface suction system to force the liquid to be cleaned from the belt filter to the NZ-50 centrifugal separator, where the solids are separated by centrifugal force (at 950 time’s gravitational acceleration). In the downstream DPS system, the foreign oils are separated and the cleaned liquid is fed back to the belt filter’s reservoir container by a recirculating pump.
This solution by STA enabled the operating life of the emulsion to be extended from 1 to 9 weeks. The employees’ skin irritations were reduced significantly.