“With the portable CMM and PowerINSPECT, we just print out the inspection report ...”

Most production is prototype jobs of 5, 10 or 50. But Friendship also has some jobs that run in the thousands of pieces annually. These go into (or more accurately, underneath) pickup trucks, SUVs, school buses, and the civilian and military versions of the Hummer all-terrain vehicle.

Friendship sells directly or indirectly to all but one of the North American car manufacturers. Its biggest customer is American Axle & Manufacturing (AAM), a $4 billion-a-year Detroit-based supplier of suspension systems. Much of Friendship’s direct sales are aftermarket replacement parts for high-performance cars.

Tooling is simple: curved bending blocks welded onto steel tables. The geometry of the bars’ bends is inscribed into the steel table top. The real work is done by the benders -- Friendship employs about 10 -- who combine sharp eyes and well-honed skills with strong arms and broad shoulders.

To make sure it all comes out correctly, Friendship relies on a portable CMM.

The model 1000i arm was chosen because of its nine-foot reach and repeatable accuracy of +/- 0.003 inch.

PowerINSPECT software was chosen for use with the arm “because of the flexibility in the way we can use it,” explained Francis Blake, who also oversees production. “We rely on the software a lot for its reverse engineering capabilities.” This is how Friendship ensures that customers’ geometry is correctly transferred from the drawings (almost always 2D AutoCAD files in the DXF or 2D DWG formats) to the bending tables and the inspection room.

“In addition, only the combination of the portable CMM and PowerINSPECT would accurately measure the amount of deformation in the curves of sway bars,” he continued. “This is especially important with the heavy wall tubing from which many of our products are formed. The circumferential deformation must never be less than 85 percent of round or more than 115 percent across the rod or tube’s outside diameter. If the deformation exceeds those limits, the sway bar’s stiffness and load-transferring capability are compromised,” he pointed out. “That bar’s production lot would be rejected.”

Friendship inspects its stabilizer bars to determine accuracy directly rather than measuring the tooling itself. While the latter, indirect methods are the prescribed way of doing things in ISO 9002-certified plants (as Friendship is), it is beside the point here. Friendship’s process is virtually all manual and final part dimensions ultimately depend on the skill and judgment of the worker. This is what Friendship’s inspections verify.

“The other measurement systems we investigated assumed that the steel bar or tubing was still round after bending,” Francis pointed out. “This is not the case with stabilizer bars, however, since the amount of deformation at each bend is a critical dimension. That deformation is what determines the balance of stiffness and flexibility that makes the stabilizer work,” he explained. “The only way to determine deformation is by taking several coordinate points around the circumference of the bar or tube at the apex of each curve.”

In PowerINSPECT, each job is set up in terms of cylinders (straight bar segments), axial rotations and bends. The software even prompts the user through the process step by step.

“With the arm and PowerINSPECT, we just print out the inspection report,” Francis summarized. “The customer can then compare the tolerances, norms, actuals, deviations, and errors with the original CAD drawings or with the engineering specifications. We and they are very happy with arm and PowerINSPECT.”