Rework or Scrap?

Charles D. Schultz

President at Beyta Gear Service
Charles D. Schultz is President of Beyta Gear Service and one of Gear Technology's technical editors.

Latest posts by Charles D. Schultz (see all)

My last posting on surface temper inspection prompts me to think about the problem of non conforming components. It is never fun to throw valuable parts into the scrap hopper but often it is the only decision that makes sense. Reputations that took years to make can be destroyed instantly if defective parts are knowingly put into service.

An old boss was fond of reminding that “anyone can make a part right the first time but it takes a real craftsman to fix a reject.” When your business is custom, high value components it pays to have many craftsmen on your team. It also influences your part designs and process planning when individual parts cost thousands of dollars and making replacements can take months.

Those making high volume low cost components face a different decision tree. Rather than worry about the fate of individual parts or even a batch of parts, volume producers have to use non-conforming reports to diagnose material, heat treat, or process problems and to develop ways to fix those problems quickly without shutting the line down.

I am an advocate of getting many team members involved in the non-conforming part evaluation process. No one department made the defects and no one department can fix them. Sometimes problems are created by team members not understanding how their actions or inaction effects subsequent operations. Chips not removed from tapped holes before carburizing come to mind; as an apprentice I spent a day with a die grinder removing 60 Rockwell chips that could have been removed in ten minutes while soft.

Getting a cross section of the team involved in part triage helps educate the workers on defect causes and gives them an opportunity create process improvements. Sometimes just changing the sequence of operations will improve overall yield. Design changes may also be indicated by the frequency of defects.

Quality Assurance is part of every team member’s job. Just doing your job right may not be enough to produce “good” parts so it is your best interest to understand how your work influences other operations and the final product that reaches the customer.

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