Investigation of a Unique Macro/Micro Laser Machined Feature for Mechanical Face Seals With Low Leakage, Low Friction, and Low Wear

Numerous studies have been conducted to evaluate the effects of micro dimple surface texturing on friction reduction in mechanical seals [1–7]. Optimum ratios for a dimple configuration, depth (h) to diameter (D) (Fig. 1), range from 0.02 to 0.5, and area density ratio, ratio of dimple area to seal face area, range from 20 to 55%. Within this range it has been shown that friction can be reduced by as much as 50%. These studies indicate that if the ratio of depth to dimple diameter is reduced below 0.02 a dramatic reduction in performance is seen. Also observed in one investigation [8] is the possibility that micro dimples can become filled with debris. This may degrade performance over time. This report will show that with the use of a unique macro/micro feature it is possible to achieve a reduction in friction of 65%, significantly lower face temperature, exhibit debris resistance, showing low to zero measureable leakage, and low to zero wear when compared to an untextured seal face. The term macro/micro feature is used to describe a feature that has a depth to size ratio, h/L (Fig.2), which is two orders of magnitude smaller than current dimple configurations, well below what may be considered useful from a performance standpoint. This new macro/micro feature, a tapered channel, demonstrates significant cavitation affects as well as hydrodynamic load support. These features are believed to be responsible for its low leakage as well as it low friction/wear characteristics.