Welding Industry Case Study

Background

A mid-west manufacturer of MIG and TIG welding tools, with a reputation for superior quality, used an aluminum sand casting for the main body on one of its products.

To protect the component from the elements, the sand casting was partially encapsulated in plastic. Lightweight aluminum was employed to reduce welder fatigue and allow an easy fit into the plastic case. As the aluminum component actually carried the gas, the fit was a critical factor in the assembly.

Challenge

While it was relatively inexpensive, the sand cast part carried a 3% porosity defect factor, meaning that 100% of the parts had to be pressure tested after they were machined, thereby making an expensive, non-value added operation a necessary part of the manufacturing process. To compound the problem, a percentage of those that passed the pressure test soon failed in the field, resulting in high warranty replacement costs, and more importantly, a negative effect on the company’s reputation.

A secondary concern was the sand casting’s rough appearance; a fact the company’s marketing department wanted to overcome.

When presented with the challenge, Lofthouse proposed a redesign to a forged component in aluminum alloy 6061.

Solution

The inherent properties of a forging provided pressure tightness, thus eliminating the need to perform routine, ongoing pressure testing. Warranty claims dropped to zero, and the Marketing department was rewarded with the forging’s smooth surface finish.

After the component was in operation for a few months, the company discovered that machining costs had also decreased. This was due to the elimination of porosity, as well as a higher part-to-part consistency (CPK value).

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