Research Output
Progressive tool wear in machining of aluminum alloy: The influence of solid lubricant nanoparticles
Chilled Air System and Size Effect in Micro-milling of Nickel−Titanium Shape Memory Alloys
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Publication
The abstract should summarize the contents of the paper in short terms, i.e. 150–250 words. Aluminum alloy 7075 are used in a variety of applications particularly in automotive and aerospace industry owing to their features of lightweight, high-strength and corrosion resistant properties. However, build up edge (BUE) and material adhesion either on cutting tool or workpiece render these materials difficult to machine. Their machining is associated with rapid tool wear and poor workpiece quality. Cutting fluids are currently the common solution to these problems although there are concerns on their use in terms of health footprint and environmental effects. Thus, new innovations are crucial to enhance the machinability as well as diminishing hazards through encouraging greener machining techniques. In this research, the use of solid lubricants; graphene and hexagonal boron nitride nanoparticles to augment minimum quantity lubricant were researched in macro drilling. Effects of four different machining conditions namely dry, minimum quantity lubricant, minimum quantity lubricant dispersed with graphene and hexagonal boron nitride nanoparticles were investigated on their progressive tool wear behavior. A notable finding is that the nanoparticles of solid lubricants had a significant factor in improving machinability of aluminum alloy 7075 compared to dry and minimum quantity lubricant alone. It was observed that the use of minimum quantity lubricant dispersed with hexagonal boron nitride demonstrated desirable tool life enhancement, tool wear reduction and number of holes drilled increment.
Publication
Although Nickel-Titanium Shape Memory Alloys (NiTi SMAs) are used in a variety of applications due to their shape memory and superelasticity properties, their features of high ductility, temperature sensitivity, and strong work hardening render these materials difficult to machine. The viability of a new approach in improving the machinability through temperature control using chilled air system application was investigated. Differential scanning calorimetry was used to characterise material response to thermal loads. Microstructure phase identification was evaluated with X-ray diffraction. Micro-milling tests were performed using chilled air system and benchmarked to dry cutting and the use of minimum quantity lubricant (MQL). To augment lubrication, chilled air was also applied concurrently with MQL. Results indicated that the application of chilled air reduced cutting temperature and minimised burr height, while their simultaneous application with MQL further improved the machinability. Further investigation was conducted to explore the influence of the ploughing mechanism on machining performance and product quality. The results pointed to higher feed per tooth producing better outcomes. This paper puts forward a new hypothesis that the machinability could be improved by inhibiting or locking in phase transformation through temperature control, and optimising chip thickness, one of the principal parameters of size effect.