Study of Peck drilling of borosilicate glass with μRUM process for MEMS

Right selection of process parameters is the most important decision to achieve superior quality of micro hole such as less edge chipping, less taper of hole and accurate diameter of drilled hole on brittle ceramic materials. Peck drilling methodology has been adopted to drill 1 mm thick borosilicate glass (bk7) material and a mathematical formula has been derived to estimate material removal rate (MRR) in peck drilling. Present work correlated inter-relationships of various μRUM machining parameters namely spindle speed, distance traverse in each stroke; feed rate, vibration amplitude and vibration frequency on edge chipping area, taper and cutting force using response surface methodology (RSM) for peck drilling operation. The experimental results revealed that spindle speed, distance traverse in each stroke; table feed rate, vibration amplitude and vibration frequency significantly affected the edge chipping area and taper size; while distance traversed in each stroke and table feed rate affected the cutting force. The validation of the developed model showed that the edge chipping area, taper and cutting force of μRUM of borosilicate glass could be estimated with reasonable accuracy using second order models. Trust region method for nonlinear minimisation was used to find the optimum level of parameters for minimising edge chipping area. Optimised parameters were used to realise actual job and carried out 114 numbers of Ø300 μm hole drilling on bk7 work material successfully.