During the beerewing process , the wort is produced in the brewhouse. For this purpose, sugar is dissolved from the malt, which is necessary for fermentation and alcohol development. The solid and liquid phases must then be separated again. The residues of the malt, the so-called brewer grains, serve as filter aids. To obtain the desired filter layer in the process tank, the brewer grains are allowed to sediment at the bottom of the tank. This leads to an increase in filtration efficiency and ultimately to an impenetrable layer. To make it permeable again in a controlled manner, slits are cut into the spent grains with the knives of the so-called chopper. As a result, a controlled movement takes place again. After complete separation of the liquid and solid phases, the brewer grains must be removed from the lauter tun. Various technical devices are used for this purpose.
The Kaspar Schulz company developed the so-called jackknives for this purpose. The knives, which are used to slit the brewer grains, are rotatably mounted. When the chopping unit rotates clockwise, the knives cut the brewer grains. When the chopping unit rotates in the opposite direction, the knives fold over and push the brewer grains towards a discharge opening. No further actuators or cylinders are required.
During the process, the equipment in the process vessel is exposed to a wide range of adverse influences. These requirements also applied to the bearing of the jackknives, for which a suitable solution had to be found.
The material of the bearing had to be able to withstand changing temperatures between 0 and 120°C as well as cleaning with aggressive chemical cleaning agents without any problems and had to have FDA approval.
Previously, gunmetal bearings were used to mount the knives, which were difficult to work with, showed signs of wear when in contact with some cleaning agents, and were not FDA compliant. In addition, they expanded rapidly in hot conditions and had to be adjusted for cold or warm conditions.
Among other things, for the bearing of the jackknives described, the company Kaspar Schulz has since that time used plain bearings made of the material iglidur A500, which meets all the customer's requirements.
This means the extreme temperatures are no challenge for these iglidur plain bearings, which operate in application ranges from -100°C to +250°C.
The use of organic raw materials as well as the hygiene and cleanliness requirements of a food processing plant necessitate the use of chemical cleaning agents and disinfectants. The resistance of iglidur A500 against all relevant chemical compounds allows the choice of the preparation to be adapted to the contamination and not to the materials used. And the bearings were also able to solve the problem of completely removing the chemical cleaning agents after the cleaning process due to their low water absorption.
Finally, the material properties were allowed to change only insignificantly over the entire temperature range as well as during cleaning with steam, which the high-performance material fulfils with a coefficient of expansion of approx. 0.0001/K. Overall, by the application of the iglidur plain bearing an increase in the service life of about 280% compared to the previous gunmetal bearing could be achieved.
