Enhancement of wet- and MQL-based machining of automotive alloys using cutting tools with DLC/polymer surface treatments

Machining experiments using tooling prepared with thin perfluoropolyether (PFPE) lubricant films, which were applied to diamond-like carbon (DLC) PVD coatings, were compared to traditional tooling used in wet-machining conditions for the drilling of a cast aluminum-silicon B319 alloy. Multi-layered DLC + PFPE coatings show promise under minimum quantity lubrication (MQL) machining conditions of aluminum alloys. The positive impact on performance of this surface treatment is compared to wet machining by studying tool life, wear behavior and chip formation using coated cemented carbide drill bits. Cutting torque was measured in situ together with the characteristics of the chips. Also the chip cross-section micro-structure was evaluated using a scanning electron microscope (SEM).