In the 1880s, American scientists took the lead in evaluating cutting fluids. F·W·Taylor discovered and clarified the phenomenon and mechanism that using a pump to supply sodium carbonate aqueous solution can increase the cutting speed by 30% to 40%. Since the tool material used at that time was carbon tool steel, the main function of the cutting fluid was cooling, so the term "coolant" was proposed. Since then, people have called cutting fluids cooling lubricants. With the continuous improvement of people's understanding of cutting fluids and the continuous enrichment of practical experience, it is found that injecting oil into the cutting area can obtain a good machined surface. At first, people used animal and vegetable oils as cutting fluids, but animal and vegetable oils are easy to deteriorate and have a short service life. At the beginning of the 20th century, people began to refine lubricating oil from crude oil and invented various lubricating additives with excellent performance. After World War I, compound oils synthesized from mineral oils and animal and vegetable oils began to be studied and used. In 1924, cutting oils containing sulfur and chlorine were patented and used for heavy cutting, broaching, threading and gear machining.