This article was published in February of this year by authors from Lagos State University in Nigeria.  The paper compares the effect on a mild steel when the metalworking fluid is varied.  Test were run using water, palm kernal oil, water soluble oil, and even dry cutting.  Tests were run at 355 rpm using Tungsten Carbide and High Speed Steel tooling. The resulting surface hardness of the samples was compared and related to the metalworking fluid and tooling.