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The demand for miniaturized device and components is rapidly increasing in fields of aerospace, energy, optics, electronics and communication, automation and medical. Rotary Ultrasonic Machining (RUM) is capable of machining hard and brittle materials such as advanced ceramics, glass and silicon used in many industries. Rotary Ultrasonic Machining (RUM) is a hybrid machining process in which material is removed by conventional grinding and ultrasonic machining. Micro RUM is a downscaled version of a macro RUM and is similar to micro Ultrasonic Machining (micro USM), where the vibration takes place in work piece instead of tool.
The goal of this thesis is to conduct a feasibility study and investigate material removal mechanism for micro rotary ultrasonic machining (micro RUM). The effect of the spindle speed, tool tip geometry, static load, coolant, coolant concentration, work piece property on the material removal rate (MRR) and tool wear of micro RUM was studied. In RUM water is normally used as a coolant. In this study, milk was first introduced as new slurry in micro RUM and comparison experiments were conducted by adopting water with conventional polycrystalline diamond (PCD) powder mixture and water only as slurry. It was discovered that as MRR increase with an increase in the spindle speed, vibration amplitude and static load irrespective of type of working fluid. Milk as a working fluid resulted in the higher MRR, a better surface finish and less tool wear as compared to water, honey, coffee and PCD slurry as working fluids. Capability of micro RUM process for machining bovine bone was investigated. It was also found that viscosity of coolant plays a vital role in the material removal process. Temperature rise during machining was recorded using micro thermocouples. Scanning Electron Microscope (SEM) examination at higher magnifications revealed that using milk as the coolant showed a higher occurrence of ductile mode than water as a coolant. Milk was used as a working fluid during machining of bovine bone because viscosity of milk and blood is 20, 10 centipoises respectively. Surface quality of bone machined part using micro RUM is much better than other traditional and non-traditional machining methods. Finally, material removal rate predictive model was proposed and verified.
Advisor: Kamlakar P.Rajurkar