Tool wear analysis in milling of medium carbon steel with coated cemented carbide inserts using different machining lubrication/cooling systems

摘要

Currently, higher production rate with required quality and low cost is the basic principle in the competitive manufacturing industry. This is mainly achieved by using high cutting speed and feed rates. Nevertheless, elevated temperatures in the cutting zone under these conditions shorten tool life and adversely affect the dimensional accuracy and surface integrity of component. Other properties such as the strength, hardness and wear resistance of the tool can also be affected. Thus it is necessary to find optimum cutting conditions (cutting speed, feed rate, machining environment, tool material and geometry) that can produce components in accordance with the project and having a relatively high production rate. It is known that cutting fluids, when properly chosen and applied, are used to minimize problems associated with the high temperature and high stresses at the cutting edge of the tool during machining because of the lubrication, cooling, and chip flushing functions of the fluids. Also, the effectiveness of fluids depends on their ability to penetrate the chip-tool interface and to form a thin layer in the shortest available time, either by chemical attack or by physical adsorption, with lower shear strength than the strength of the material in the interface. If the effectiveness of cutting fluids or any other machining environment (atmospheric air and argon) affects tool wear rate and failure modes, the understanding of the tool wear mechanisms becomes essential for the improvement and development of better tool materials and designs. The knowledge of this process will help to minimise tool wear, thus ensuring a higher production rate. This paper presents a comparative study of the influence of two machining environments (dry and wet) in tool wear and surface quality during end milling of AISI 1047 steel with carbide tools. Fluids were directed to the cutting zone by three different techniques: flooding, reduced flow rate and MQL. The results showed that longer machined length values and higher material machining removal volume were obtained when machining using reduced flow rate system. Also, this system prevent chipping. SEM analysis of worn tools indicated that the wear mechanisms existing during machining are affected by machining environment.