Experimental investigation and finite element analysis of the effects of spindle speed and feed rate on hole quality in micro drilling of Monel 400 alloy

Excessive thrust force in micro drilling of difficult to cut materials like Monel alloys poses challenges such as tool breakage, burr formation, and poor hole quality. So optimizing the thrust force is crucial for reducing the tool wear and improving the dimensional accuracy. This work uniquely combines finite element (FE) simulation with experimental validation to evaluate and optimize the effects of spindle speed and feed rate on thrust force, circularity error, and burr formation in micro drilling of Monel 400 alloy. Nine experimental trials and FE simulations with different spindle speeds and feed rates were conducted to evaluate the drilling performance. In addition, three drilling tests were carried out at higher feed rates for assessing its influence on thrust force and drilling quality. Comparison of experimental and simulated thrust forces across varying feed rates and spindle speeds showed strong agreement, with deviations ranging from 1.2% to 5.3%. The influence of cutting parameters on the circularity of holes, burr width, and length at both the entry and exit edges was systematically evaluated. The results demonstrate that higher spindle speeds combined with lower feed rates lead to the lower thrust force (1.703 N), improved hole circularity (entry: 0.6272 mm, exit: 0.6216 mm), and reduced burr formation (entry: 0.27 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mspace width="0.25em"/> <mml:mrow> <mml:mi>μ</mml:mi> <mml:mi mathvariant="normal">m</mml:mi> </mml:mrow> </mml:math> , exit: 0.16 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi>μ</mml:mi> <mml:mi mathvariant="normal">m</mml:mi> </mml:mrow> </mml:math> ). The findings highlight the optimal spindle speed and feed rate to minimize burr and enhance hole quality in micro drilling of Monel 400 alloy.