Romer’s Portable CMMs Boost Productivity in Custom Fire Truck Cabs
Romer CimCore 3000i Portable CMM

For many companies, outsourcing may be just the thing to tune up productivity in operations. But outsourced inspections have been anything but a productivity booster for the nation’s largest builder of custom fire trucks, Pierce Manufacturing Inc. of Appleton, Wisconsin.

“Before we purchased our own inspection machines, we were at the mercy of when we could get a contract coordinate measuring machine (CMM) service to help us,” says Don Nennig, a manufacturing engineer who programs the portable CMM arms used at Pierce. “We were sending many parts out to an outside firm with a CMM machine. Inspections cost roughly $300 each and, if they were backlogged, several days of delay in running the parts. It was a big expense.”

Pierce now has two 3000i portable CMMs from Romer CimCore, a unit of Sweden’s Hexagon AB. Both CMMs are equipped with PowerINSPECT from Delcam PLC. Romer provides pre-sale and post-sale support, application assistance, training and ongoing telephone support for the complete CMM system. These portable CMMs travel to the parts and fixtures rather than the parts traveling to contract CMM shops. No longer do those road trips determine when work will start on new parts.

Pierce’s 150,000 sq ft Appleton plant fabricates nearly all the components for its cabs and chassis and all its assembly fixtures, so it is highly vertically integrated. Pierce builds more than 1,300 custom fire trucks a year, and employment is about 1,600. The company, which is registered to ISO 9001:2000, is part of Oshkosh Truck Corp. of Oshkosh, Wisconsin.

Pierce builds high-end fire apparatuses, with most units costing upward of $200,000. Both the production rate and the backlog are significant. “We are always trying to find ways to increase our production while we maintain the high quality that Pierce is known for,” Nennig states.

“We do a lot of first-article inspections as new parts come in from suppliers,” he continues. “Getting those done fast and accurately is the key to production efficiency, and this is accomplished very effectively with the CMM. Data from the first-article inspections allow us to apply continuous product improvement methods to our new castings and composite parts. Every part can be accurately scrutinized and the results compared over time.”

The most sophisticated work undertaken with the Romer CimCore portable CMMs has been obtaining a surface model of the windshield to insert into the solid model for design of the cab windshield openings. Each of these glass pieces measures roughly 44 ! 32 in. and is curved in both axes. The glass is held in place by hand-stamped aluminum trim parts, and achieving dimensional precision has long been a production bottleneck. “Without the CMM it would have been virtually impossible to create a sophisticated set of fittings for each of the windshield panels,” Nennig says.

The cabs’ A pillars were a similar CMM challenge. In Pierce’s cabs, the A pillar is the origination point for all dimensions. “If the A pillar is off, everything will be off,” explains Nennig.

“It was taking us three to four hours to form each of these pillars--tap, adjust and check, saw, hammer, weld and grind,” says Ryan Lang, a Pierce manufacturing engineer assigned to cab fabrication. Because the A pillar itself is curved in two axes--in part to hold the outside edge of the windshield glass--its tooling is among the most complex.

When producing fire truck cabs, everything at Pierce revolves around seven large welding fixtures. They are for wheel wells, doors, step box assemblies, engine tunnel assemblies, roofs, sides and rear walls. Pierce makes six different cabs, built on five distinctly different weld assembly fixtures. Bolt-on stops accommodate the multiple sizes of otherwise standard fabricated aluminum components. Sheet metal components for each cab are manually fitted into the final assembly fixture and rest on the stops as they are arc-welded together.

The CMM minimizes the human factors that are responsible for so many measuring errors. Even better from a day-to-day use standpoint, if a dimension is off in some manner, it will quickly be obvious. “You know that there has been an operator error and you can see it,” Lang continues. “We correct our error and keep on measuring.”

Romer CimCore 3000i Portable CMM

Benefits:

• Decreased setup times for stops on welding fixtures
• Increased dimensional integrity of cab structure
• Reduced troubleshooting time
• Better dimensional control over new parts from new vendors

www.romer.com