Harnessing the quality engine: Honeywell's phoenix aerospace plant uses a dedicated CMM to ensure quality and reduce costs in a high-volume manufacturing cell

Modern Machine Shop, March, 2002 by Bill Dundas

Compared to the process that would be required to produce this type of part with conventional machines, Honeywell garners substantial savings with its multi-process machine. The labor of at least five people would be necessary to produce these parts using multiple drill presses and grinding machines. With the multi-process machine, however, Honeywell needs only one operator, and no manual machine setups are necessary. "The new equipment has significantly reduced both the production cost for these parts and our lead time," says Honeywell's project manager Chip Svoboda.

Although Honeywell currently deburrs the nozzle segment parts manually--presently representing a considerable amount of time in the overall production process--the company is developing plans to equip the Hitachi Seiki machining centers with special deburr brushes to automate this task.

In-Process Analysis

The capabilities of the CMM and its controlling software have helped Honeywell move beyond the paradigm of quality control as a post-mortem examination. "Now we have much more information about the machining process," says Mr. Svoboda. "In the past, we didn't have this data--just the operator's comment that a particular part was good or bad."

Because a primary goal of any manufacturing process is to reduce variations, Honeywell has met this challenge by initiating a comprehensive quality strategy known as Six Sigma Plus. Defined strictly in numerical terms, this standard establishes the goal of achieving fewer than 3.4 defects per million opportunities. But from a broader perspective, this target assumes the implementation of a company-wide strategy that predicates the firm's future growth on the continuous improvement of every product and service.

It's a well-known metalworking principle that the number and severity of variations in mass-produced parts will increase gradually as the result of advancing tool wear. The CMM enables Honeywell to rapidly measure each finished part and to combine the measurements of many parts within a historical database. This data enables Honeywell to better control its machining process.

In particular, the company can predict tool consumption rates more accurately and standardize its tool change intervals. For example, four separate grinding operations are necessary to finish the surfaces of Honeywell's nozzle segments. By examining tolerance drift on charts generated by the CMM software as production continues, replacement intervals for CBN grinding wheels can be established according to actual grinding conditions. This improves wheel utilization by eliminating reliance on rule-of-thumb estimates that may not reflect certain variables in a particular grinding operation.

Because they were accustomed to measuring with hard gages, Honeywell's operators found that the CMM's greater accuracy demands more attention to process parameters. "Our inspection process does not allow any out-of-tolerance features, so we have initially spent a considerable amount of time chasing errors in the range of 0.0001 inch," says Mr. Svoboda. "The CMM forces us to go back and examine our manufacturing process in much more detail."