The Pareto diagram and Line diagram reveals major defect is M8 Nut failure as shown in Fig. 3 & Fig. 4 respectively. This defect occurs during welding operation in weld shop. M8 Nuts weld on Cross Member part with the help of projection welding which plays essential role for assemble automobile subassemblies part.
The potential failure mode of M8 nut are (a) peel strength to tension less than required values (b) thread damage (c) nut position shifted w r t centre of hole (d) nut miss. Some of potential effects due to above mentioned failure mode are (a) subassemblies will become functionally impaired & weak (b) problem in bolt tightening (c) pitch of mounting holes will be effected. These potential effects of failures occur throughout the life of the Cross Member part which is very critical mainly for maintenance, accidental & safety purposes throughout the life. If we are able to eliminate the major failure M8 Nut fail, the defective level can be brought down to 0.0181 % from the present level of 0.0357 %. The principle of Pareto diagram also states that investment in improvement of vital few yields better than compared to investment in trivial many. Hence Cross Member defects in M8 Nut failure was taken up for investigation.