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Case Study 3 :Cost Reduction - Combine the bobbin and stem
Initial Design is a not good design with a higher cost and worse geometrical tolerance - eccentricity.
It needs to do the many times of manufacturing processes - plastic injection molding, joining as follows:

This composite part consists of Terminal-1,Terminal-2,
Magnetic Bushing, Stator, Plastic Stem. The manufacturing Process is
Plastic Injection Molding(stem) -> Plastic Injection Molding Assembly (Terminal-1,Terminal-2, Magnetic Bushing) -> Joining the Assembly, Stator, Stem.
Use the plstic injection molding to combine Terminal-1, Terminal-2, Magnetic Bushing and Bobbin. Here one plastic mold.
Here do another plastic injection molding part - stem first. Here another plastic mold. And then making the joining to combine these parts - that part in last figure, stator, and stem. Here produces a geometrical tolerance problem - eccentricity and has a defective rate around 20% due to the joinging. This problem causes a oil leak and higher pressure drop.
The complex part is produced with the above processes, but has the higher cost and worse geometrical tolerance.
The known problem:
Improved joining method by SINS to achieve this target:
Prepare the parts here as the right figure.
Doing the plastic injection molding with these parts one time to have the bobbin and stem. According to the measure, the eccentricity is controlled within 0.03mm with a excellent geometrical tolerance. In addition, the initial cost is reduced around 40%.

Conclusion:
By using a new technigue - plastic injection molding with multi-parts, the manufacturing processes can be reduced to one time. In addition, the
cost can be reduced 40% only with one plastic mold less than initial two ones. The defective rate with a worse geometrical tolerance has been
reduced to a excellent value, 1%.


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