Study of different cutting strategies for sustainable machining of hardened steels

This paper studies the power consumption of different cutting strategies in face milling operations in order to evaluate the efficiency of each cutting strategy. The experimental procedure evaluates the machine-tool efficiency by estimating cutting forces and measuring the power consumption. After modeling the efficiency of the machine-tool at different states (idle, fast movement and cutting at different conditions), the cutting strategies and cutting parameters are analyzed and compared in terms of sustainability (CO2 emissions) and quality (surface roughness). The optimal cutting strategy to ensure a predefined quality specification is also derived.Vila, C.; Abellán Nebot, JV.; Siller-Carrillo, HR. (2015). Study of different cutting strategies for sustainable machining of hardened steels. Procedia Engineering. 132:1120-1127. doi:10.1016/j.proeng.2015.12.604S1120112713

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

Evaluation of cutting force and surface roughness in high-speed milling of compacted graphite iron

Compacted Graphite Iron, (CGI) is known to have outstanding mechanical strength and weight-to-strength ratio as compared to conventional grey cast iron, (CI). The outstanding characteristics of CGI is due to its graphite particle shape, which is presented as compacted vermicular particle. The graphite is interconnected with random orientation and round edges, which results in higher mechanical strength. Whereas, graphite in the CI consists of a smooth-surfaced flakes that easily propagates cracks which results in weaker and brittle properties as compared to CGI. Owing to its improved properties, CGI is considered as the best candidate material in substituting grey cast iron that has been used in engine block applications for years. However, the smooth implementation of replacing CI with CGI has been hindered due to the poor machinability of CGI especially at high cutting speed. The tool life is decreased by 20 times when comparing CGI with CI under the same cutting condition. This study investigates the effect of using cryogenic cooling and minimum quantity lubrication (MQL) during high-speed milling of CGI (grade 450). Results showed that, the combination of internal cryogenic cooling and enhanced MQL improved the tool life, cutting force and surface quality as compared to the conventional flood coolant strategy during high-speed milling of CGI