Check for prints

Oct. 26, 2006
Clear, Up-To-Date Engineering Drawings Are Key To Accurate Parts.

Craig Slass
Rotor Clip Co. Inc.
Somerset, N.J.

Edited by Lawrence Kren

The first thing a good detective does at a crime scene is check for prints. Fingerprints, of course, are unique to every individual. Similarly, components should always match the engineering prints from which they were made. This may seem obvious, but it is surprising how often they do not.

As a component manufacturer, we are constantly reviewing prints to ensure they match stated specifications and any samples we are provided. The slightest variation — an incorrect tolerance or specification — can cause great confusion between what the print says and what is actually produced.

Case in point: One of our distributors was purchasing a retaining ring for a large OEM as part of a vendor-managed inventory program. The buyer said that the part was beveled (a ring used to take up rigid end play in an assembly) and that it was made of phosphor bronze.

I passed the request to our technical sales engineer. He reminded me that this particular beveled part was not standard, which got me thinking: I've seen this part before. In fact, I remembered it as a part for a marine application some years before. Because the distributor had only given us a competitor's part number, I asked him to provide a print.

The buyer was reluctant, claiming that he fully knew the part specifications and required material. The extra step wasn't necessary, he insisted. However, after a bit more prodding, the customer relented and provided the print.

Our engineer was shocked. The print called for a standard ring, not the special beveled one that the customer initially requested. The discovery came as a surprise to the buyer as well. He was also extremely grateful. He was about to give the order to a competitor who told him he would have to purchase a minimum of 27,000 parts, a two-year supply, when he only needed 10,000. Scrutinizing the print prevented delivery of the wrong part to his customer as well as a $67,000 error.

Prints are difficult to keep current. Changes are often made in the heat of solving a problem, and, in many cases, someone neglects to change the print to reflect this. Or, the revision is made but not sent to the appropriate supplier so the revision level can be updated. Whatever the reason, out-of-date prints can lead to production of the wrong part, costly returns, and serious liability issues.

Keeping prints up to date and making sure there is a system in place to communicate changes to your suppliers makes good business sense. It also eliminates the dual crime of waste and needless expense.

Rotor Clip Co. Inc. ( is a maker of retaining rings.

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