Protocol for tool wear measurement in micro-milling

Micro-milling yields small accurate parts quickly for electromechanical, aerospace, and medical applications. Due to their small size, micro-tools wear quickly and unpredictably therefore tool wear is difficult to measure and is poorly understood, leading to excessive tool changes and reduced productivity. This paper, therefore, proposes a new protocol for micro-tool wear measurement to overcome these problems. A strict set of criteria as found in an ISO standard is impractical for micro-milling research. The method herein allows comparisons to be made across materials and situations and detailed are certain criteria that must be fulfilled to achieve this. To evaluate the protocol micro-tools were used to machine three materials: brass, titanium and Hastelloy; and wear curves produced. Using the described protocol, these wear curves can be analysed similarly to those for larger tools. Profile analysis of the slots machined provides valuable information about tool wear where direct measurement is impossible. This new protocol presents a novel method for analysing and reporting tool wear for micro-end-mills, allowing them to be compared under different machining conditions and/or milling different materials, something not afforded by existing machining standards. The information can then be transferred to industrial applications, extending tool life and improving process efficiency.