నైరూప్య

Failure Analysis of Solid Carbide Cutting Tool Used in Milling Operation

V. Gnanasekaran, J. Ekanthamoorthy and K. Senthilkumar

Cutting tools are subjected to frequent failures during machining. Such failures are due to chip formation, wear and chattering. The main objective of this work is to find optimal cutting parameters for enhancing the tool life of the chatter free end mill cutter (ISCAR) while machining MDN 321 steel and to establish process failure mode and effect analysis (P-FMEA) for the end milling process. This project was conducted in Precision Machining Centre (PMC), L & T Coimbatore. Preliminary studies were done to find out the frequently occurring cutting tool failure by using standard quality tools. Pareto chart and fishbone was constructed for the end milling process. Based on the common failures of the milling cutter a Design of experiment (DOE) was formulated to find out the optimal cutting conditions for tool wear and surface roughness. Based on the fishbone diagram, risk priority number (RPN) was calculated for each mode of failure. The preventive steps and procedures were suggested to the failures with high RPN. From the preliminary studies it has been found out that 34.6% of failure is occurring in ø12 chatter free end mill cutter. The optimized cutting condition for tool wear are cutting speed of 250 m/min and axial depth of cut 0.25 or 0.50 mm. The cutting conditions for better surface roughness are cutting speed of 250 m/min, axial depth of cut 0.25 mm, and feed rate 0.10 mm/rev. From the analysis, it has been found out that chip packing due to excess cutting depth has the highest risk priority number. This can be reduced by varying the feed rate and spindle speed.