Addressing Lubrication Challenges in Extreme Conditions Experienced in Subtractive Processes in Additive-Subtractive Hybrid Manufacturing (ASHM) of AISI H13

In additive subtractive hybrid manufacturing (ASHM), the combination of machining and additive processes in a single operation combines the benefits of both processes and thus enables the creation of high-quality complex parts. However, this method presents various challenges, particularly during the subtractive or machining steps. The machinability of parts produced through additive manufacturing is often low due to different factors such as high residual stresses and the presence of fine, hard microstructures. Furthermore, in ASHM intermediate heat treatments is not possible which results in subsequent increase in hardness of the printed workpiece material. Additionally, cutting fluids are unsuitable for controlling temperature and friction in ASHM because printing and machining occur simultaneously in the machine. The cutting fluid can contaminate the build environment, affecting layer adhesion and thus being detrimental to the printing operation. This study investigates the use of novel soft metallic lubricant coatings in ASHM, as a substitute for conventional fluid lubricants to address the lubrication challenges in the machining step. The novel proposed coating primarily serves as a lubricating layer between the tool and the workpiece material and provides an effective alternative to cutting fluids. The research aims to assess the effectiveness of these lubricant coatings in improving the surface integrity of additively manufactured parts, exploring a new way of machining without traditional fluid lubricants which is vital for the advancement of ASHM.