Minimum Quantity Lubrication (MQL) applications in automotive power-train machining

Minimum Quantity Lubrication (MQL) is a near-dry machining method that may be applied to reduce coolant usage in operations such as drilling, which cannot be performed completely dry. Although significant research has been reported on MQL, relatively little information on production applications and experience has appeared in the technical literature. The most common high-volume production application for MQL is cross and oil hole drilling on steel crankshafts. This paper reviews MQL test results for deep hole drilling of forged steel and cast nodular iron under conditions similar to crankshaft oil hole drilling. The results show that MQL can yield tool life equivalent to gun drills at higher penetration rates under these conditions. This result is consistent with production experience with steel crankshafts, and shows that MQL may also be useful for cross and oil hole drilling of cast crankshafts. Limited test and production data for MQL machining of aluminum prismatics is also described. Significant areas for future research and development, including chip management, air quality, capability and robustness, and cost are also discussed.