Automobile alternator is an assembly of Slip Ring End (SRE) Bracket and a Drive End (DE) Bracket as the casing and the other parts are housed inside them. This customer was complaining of the binding (not freely rotating shaft) issue after assembly of the alternator though the individual parts were precisely meeting the individual requirements.
Figure 3.1 - Original Part - SRE Bracket
The customer was of the collective opinion that the issue was with the castings and was persistently calling for their attention.
Hence the SRE and DE brackets are scrutinized and it was decided to take up the SRE bracket (Figure 3.1) because it houses a bearing for the shaft in the center.
Figure 3.2 shows the simulation recreating the actual assembly operation by defining the spigot area as the fixed location and the three fastening thread areas as loading points.
Figure 3.2 - Simulation setup showing the fixed locations and the load points.
The simulation result (Figure 3.3) in terms of the potential deformation was very dramatic, capturing the tendency of the part to deform behind one of the fastening points as well as the bearing area due to the overall effect on the whole part.
Figure 3.3 - Results showing the tendency far deformation after assembly.
Figure 3.4 shows a closer view and Figure 3.5 is an alternate view for a clear understanding.
The fastener location at a weak area was clearly attributed to the failure and alternate suggestion with four balanced faster location was suggested to the customer (Figure 3.6) and implemented successfully without a failure for more than 7 years now.
Figure 3.7 shows the result of the revised design and it is observed that the part shows no tendency to deform and fail.
Figure 3.4 - Close view of the failure.
Figure 3 .5 - An Alternate View showing the failure.
Figure 3.6 - Comparative View of Original ( Left) and Raised (Right) Designs.
Figure3.7- Comparative View of Original (Left) and Raised (Right) Designs.
Though the results are amplified for better understanding, the comparison between the results of the two versions and their obvious differences found the solution and brought the problem to its logical conclusion.