Overcoming Production Challenges with Custom Fixture Machining 

Background Information

A customer approached Yumoto Electric with a molded product that required a high level of dimensional accuracy. The product had a relatively simple geometry and was being produced through injection molding. While molding seemed appropriate for the part’s shape and expected lot size, problems began to surface once actual production started.

Problem Statement

During molding, sink marks—surface depressions caused by uneven cooling—appeared in thicker sections of the part. These defects made it impossible to achieve the required precision. The customer needed a way to maintain dimensional stability without drastically increasing costs or lead time. Reproducing the part through molding would have required new tooling and additional time, so an alternative manufacturing method was needed.

Solution Implementation

After analyzing the product, Yumoto Electric’s engineers determined that precision machining could deliver the necessary accuracy if a custom fixture were designed to hold the part securely during processing.

Because the order volume was a few hundred pieces per lot, machining was a cost-effective option that could still meet the required delivery schedule. The team developed a special fixture to ensure stable clamping and repeatable positioning, allowing precise cutting without damaging the part’s surface.

Results

Switching from molding to machining resulted in significant improvements in dimensional precision and product consistency. Although the per-unit cost was slightly higher than injection molding, the overall process became more reliable, flexible, and scalable. The customer was able to meet quality standards and delivery timelines without the expense of creating a new mold.