Design of functional automotive components with requirements for cleanliness

The technical developments that have taken place in the automotive industry over the last few years explain why the issue of technical cleanliness has become so important in the manufacture of functionally-relevant components nowadays. Together with the customer’s growing demand for safety and driving comfort, the trend towards increasing performance densities whilst simultaneously adhering to ever-stricter environmental requirements remains unbroken. In consequence, the tolerances of aggregates built into vehicles are now very low and the parts are subjected to higher and higher stress levels, making them increasingly sensitive to particulate contamination. In some cases, a single particle just a few 100 micrometers in length may suffice to impair the function of a complex hydraulic system or even cause it to fail completely. A diesel injection system with an injection pressure of 2500 bars, an ESP system with valve diameters of just a few millimeters, a turbocharger with speeds of well over 100,000 revolutions per minute or a hydraulically-controlled camshaft phaser located in the engine oil circuit are all systems which could fail because of a so-called killer particle. Nozzles becoming blocked, valves jamming, damage to bearings or conductor paths in control devices shorting are only some of the reasons why such functional failures occur. As a result, component cleanliness has become a quality feature that is now specified in customer-supplier agreements and has to be measured.