Using a minimum quantity of lubricant (MQL) and a diamond coated tool in the drilling of aluminum-silicon alloys

In the last decades, the improvement in the coatings of carbide tools and in the chemical and mechanical properties of tool materials, has caused the increase of tool working life in machining processes. This fact has allowed the use of the so-called dry machining technology and also machining with minimal quantity of lubricant. There are many important factors that justify the development of such technologies, including the high costs of refrigeration, the ecological damages caused by the use of lubricants, the increasing law demands, related to the preservation of the environment, workers' health, etc. The main objective of this work is to compare the performance of the uncoated and diamond coated carbide drills, using minimal lubrication (10 ml/h of oil in a flow of compressed air) and abundant soluble oil as a refrigerant/lubricant in the drilling of aluminum-silicon alloys (A356). The results showed an irregular wear in the surface of the diamond coated drill and a decrease in the quality of the hole made by it, compared to the uncoated drill. Taking into consideration all the conclusions reached in this work, the most important one is that the performance of the process (in terms of forces, tool wear and quality of holes), when using minimal lubrication, was very similar to that obtained when using a high amount of soluble oil, with both, coated and uncoated drills. This conclusion proves the potential of using this technique in the drilling process of aluminum-silicon alloys. (C) 2002 Published by Elsevier Science B.V.