It whines. It squeaks. It whistles. A noisy water pump is just as bad as a broken fan belt. In the best-case scenario, the pump just has to be replaced. In the worst case, the engine has to be replaced. The basic problem of a broken water pump is clear: air gets in the sealing system where there should only be coolant. The inherent vibrations of the water pump can become a disruptive airborne noise. If this annoyance occurs, automobile manufacturers have to deal with the complaints, which also get back to the sealing system manufacturers like the well-known company KACO.

Smart solution

"It can almost always be traced back to the engine's operating conditions. No matter how good the seal is," explains Tobias Hoffmann, manager of product development. A parts supplier obviously has almost no influence on the engine as a whole. The interactions between the different factors are already much too complex anyway to rule out the development of vibrations entirely. "As things stand currently, this is simply impossible," adds Eckhard Ogaza, manager of the the AXIA Sealing Systems Business Division. "We really can't prevent the causes, but perhaps we can prevent the symptoms." To this end, not even a single intervention is necessary because the simple, yet clever solution is a silencer - a stainless steel ring with several tiny metal tongues.

Warm instead of loud 

KACO welds the silencer to its new sealing system CS 2 ANS  - ANS stands for "Anti-Noise Solution." The seal consists of several assemblies. The silencer has metal tongues that protrude into a hollow space between the individual parts and have a specifically defined contact to the outer wall. On the welded side, the silencer absorbs the undesired vibrations through the friction created by the tongues rubbing against the wall. All of the energy that would otherwise produce noise is discharged here as heat. "A truly obvious solution," notes Eckhard Ogaza.

The right balance 

It didn't take much to get from the idea to the design, but implementation was a different story. "Even the smallest deviation from the tolerances can cause the properties of the part to change drastically", says Production Manager Helmut Baier. Too much friction would suppress the vibrations, but could impair the seal. Additionally, each new component not only has to be perfectly integrated into the modular concept of KACO's products, but also into the fully automated production line. "We produce over 18 million water pump seals annually. To do that, we need the greatest possible speed and process reliability," adds Baier. "So we knew straightaway that we would end up relying on laser welding. After all, we had already had some good experience using this technology."