Problem

KHS' filling line for beverages containing CO2 uses a patented filling valve in which each PET bottle is pressed on by the product pressure. The bellows, which generates the contact pressure, must be able to move axially without contact in the hole surrounding it. The piston on which the bellows presses must also move axially in the hole, regardless of the momentary bellows length. For the axially movable centring of the bellows, the designers were looking for a special bearing that could withstand operating temperatures of up to 140°C and was resistant to all cleaning agents used in the beverage industry.

Solution

The perfect solution was found at igus: a special-shaped plain bearing made of iglidur X material, which is universally resistant to chemicals and exhibits very good wear resistance at high temperatures. It is attached to the bellows with a snap-on connection and slides in a hole, whereby axial relief grooves on the outer diameter of the bearing prevent the pumping action. The bearing convinces all along the line: in the test with 50 million strokes, no measurable wear could be detected.