"We're a production machine shop," said Dennis Murphy, quality assurance manager at McSwain Manufacturing, Cincinnati. The company crafts specialized parts for industries including power generation, computers, and aerospace, and also performs some light assembly. Components are fashioned on such large machinery as vertical turret lathes and horizontal boring mills, then shipped directly to McSwain's customers for assembly into gas turbine engines and other end products.

Quality control technician, Don Zapf measures a power-generation component on an inside diameter/outside diameter (ID/OD) measuring gage that has been set on a Fowler/Trimos horizontal setting instrument. Photo: Fred V. Fowler Co. Inc.

About a year ago, the company relied on gage blocks to set the more than 60 adjustable-length gages that measure the machined parts. This process was anything but simple. "You start ringing those blocks together, you're trying to hold them together, puts rods through them, dirt gets between them, oil gets between them," explained Murphy. Whoever set up the gage blocks then had to add up the total length, making sure to do so carefully lest a mistake be made during calculation. "Now all of a sudden, you're saying that I'm ten thousandths off," said Murphy. "Well, I must have missed ten thousandths'I better add a block that makes that up, and now all of a sudden you're going to cut ten thousandths off."

Potential human error was not the only source of frustration for McSwain. It often took 30 to 45 min. just to set up the gage blocks. These factors motivated the company to look for a more accurate, faster, easier way to set the gages. "We had to find something that made a permanent fix to the problem," Murphy said, insistent that the company would not accept any more gage-setting errors. That's when McSwain decided to purchase a Trimos horizontal length setting instrument supplied by Fred V. Fowler Co. Inc., Newton, MA.

The Swiss-made, granite-based, 80-in. device simplified the gage-setting process for McSwain by reducing the number of calibration steps. The operator dials in the required gage setting, locks it, and then sets the gage directly from the Trimos. The entire process takes 10 to 15 min. The company sets bore gages with the instrument as well. Murphy can also document the settings, in case of a customer inquiry. "We print out what we set [the gage] to, staple that printout to the gage request that the operator turned in to have his gage set up, and then file that," he said. Should a customer question McSwain's measurement process, the company can reference the printout.

Because of the simpler setup and reduced setting time, fewer operators were required. With the gage blocks, Murphy had to dedicate up to three inspectors to work on gage setting. Since McSwain acquired the Trimos, he only requires one inspector. Because a calculator is no longer required for gage setup, the company has also seen incidences of operator error drop significantly. Accuracy has improved from errors in the range of 0.010 in. with the gage blocks to 0.00038 in. with the Trimos. The instrument was also easy to learn. Personnel were shown how to operate the Trimos, and able to use it in only a short time.

McSwain has experienced many benefits from the length-setting instrument'greater accuracy, speed, documentation capability'and it is determined to see that these benefits last, and prevent a reoccurrence of the old gage-setting problems. "A lot of the times, with machine shops like us, you're in a fire-fighting mode," explained Murphy. "You're always reacting to problems instead of making permanent fixes. This is an actual preventive measure that's been taken."