Surface Texturing to Reduce Temperature in Mechanical Seals

Abstract

Mechanical seals are composed of two annular flat rings in contact and relative motion to ensure sealing of a rotating shaft. Because of friction in the sealing interface, a significant temperature rise can be experienced in the contact. Two decades ago, it has been shown that creating a network of shallow dimples on one sealing surface can help to create a lubricant film in the interface and thus reduce friction. Since then, many research works have been carried out on the so-called surface texturing, showing the interest of surface modification for mechanical seals. In the present work, several surface patterns, defined by numerical simulations and machined by plasma etching on stainless steel rings were tested. The rings were mounted on a test bench in which they slide against a sapphire disk counter face. This disk is transparent to infrared radiation and allows interface temperature measurements by infrared thermography. It is shown that all the tested surface texture patterns exhibit a temperature rise at least 2 times lower than with flat smooth surfaces. A slight difference between the different dimple shapes is obtained indicating that the temperature and friction are more controlled by texture area and surface roughness rather than by the texture pattern.