The topic of sealing technologies is nothing new, even decades old. However, today's requirements pose a whole new challenge to them. The influencing factor of sealing technology is reaching a significant importance. This is also clearly reflected in the development sprints of EWS Tool Technologies.
"With the introduction of EWS Matrix Seal technology, we got a solution that guaranteed 25 bar for the seals over the entire speed range of our machines," says Lorenzo La Rosa, Team Leader Application Engineering at DMG MORI Management GmbH. If more pressure was needed, additional rotary unions were available. With good emulsion quality, these could provide pressure resistance of up to 70 bar, which was necessary for the requirement profile of the high-tech machines.
The quality standard of the machines is very high, as they often work at the limits of what is technically possible - and usually around the clock. However, one problem was always present, explains Lorenzo La Rosa: "Whether EWS Matrix Seal or other sealing technologies, they all require the oil portion of the emulsion to lubricate the sealing lip or surfaces." Even a dry-running run-in process thus runs the risk of causing initial damage to the seal set. Using a dry-running technology instead is not a sensible alternative, as it is up to five times more expensive.
The challenge: On the one hand, the new rotary feedthrough technology was to reliably control pressures of up to 70 bar in a straight mold unit without an offset output spindle. On the other hand, it had to be capable of unrestricted dry running and be compact - and of course economical. "It was the interaction of the various influencing variables that first had to be analyzed. Frictional forces, hydrostatics, component geometries and manufacturing technologies had to be optimized and coordinated," says Michael Wiesenberg, project manager for sealing technology at EWS.