Case Study 1102: Part Design Improvements

This case is a continuation of the previous one, in terms of the design improvements as suggested by CRP.

Upon close examination of the design and the part drawing, it was found that the general radius was called for as 1.6 mm, whereas in the design, as well as in the actual part, a general radius of less than 1 mm was maintained. This was requested by the customer to give a better aesthetic to the part.

It is a well known fact that the increase in the radius will contribute towards improved flow, thereby mitigating the

Figure 2a - Potential Defect Concentration with Existing General Radius of 1.0 mm.

Figure 2b - Potential Defect Concentration with Specified General Radius ofl.6 mm.

Figure 2c - Potential Defect Concentration with Suggested General Radius of 2.0 mm.

Flow problems. It will also enhance the strength of the part, as well as reduce the damage during handling and use.

Flow simulations were carried out in order to find the effects of various general radii, including the existing radius of 1 mm (Figure 2a), the design specified radius of 1.6mm (Figure 2b) and the suggested radius of 2mm (Figure 2c).

Figure 2d - Suggestion for radius improvements at various places.

The results helped CRP to persuade the customer to agree on the suggested general radius of 2.0 mm. This was implemented in the new die, resulting not only in the plunger velocity reduction from 2.2 to 1.5 m/sec, but also resulted in the reduction of process rejection from more than 25% to less than 7%.

It was a different story altogether when the same cus­tomer appreciated the new design for its better aesthetics due to the improved radius (Figure 2d). At last it was a tale of "radius conquering the sharp edge."

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