A DMAIC approach for process capability improvement an engine crankshaft manufacturing process


1 Department of Mechanical Engineering, GMR Institute of Technology, Rajam, 532127, AP, India

2 Department of Industrial Engineering, GITAM University, Visakhapatnam, 530045, AP, India


The define–measure–analyze–improve–control
(DMAIC) approach is a five-strata approach, namely
DMAIC. This approach is the scientific approach for
reducing the deviations and improving the capability levels
of the manufacturing processes. The present work elaborates
on DMAIC approach applied in reducing the process
variations of the stub-end-hole boring operation of the
manufacture of crankshaft. This statistical process control
study starts with selection of the critical-to-quality (CTQ)
characteristic in the define stratum. The next stratum constitutes
the collection of dimensional measurement data of
the CTQ characteristic identified. This is followed by the
analysis and improvement strata where the various quality
control tools like Ishikawa diagram, physical mechanism
analysis, failure modes effects analysis and analysis of
variance are applied. Finally, the process monitoring charts
are deployed at the workplace for regular monitoring and
control of the concerned CTQ characteristic. By adopting
DMAIC approach, standard deviation is reduced from
0.003 to 0.002. The process potential capability index (CP)
values improved from 1.29 to 2.02 and the process performance
capability index (CPK) values improved from
0.32 to 1.45, respectively.