Automated gaging helps win the race

END USER: Conroe Machine LLC, (936) 494-2566, www.conroemachine.com.
CHALLENGE: Increase throughput and reduce scrap when machining thrust bearing races for down-hole mud motors.
SOLUTION: An automated gaging system integrated into a turning cell.
SOLUTION PROVIDER: Renishaw Inc., (847) 286-9953, www.renishaw.com.

Conroe (Texas) Machine LLC is doing what most machine shops only dream of—hard turning a family of parts around the clock in an unmanned cell that operates a “self-controlled” process. The finish-turning cell integrates a FANUC M20iA 6-axis robot with the Equator gaging system and EX-IO software from Renishaw Inc., Hoffman Estates, Ill., to provide 100 percent part inspection and automatically compensate the cutting tools on an Okuma 2SP-250H twin-spindle, dual-gantry lathe.

Founded by Murray “Tippy” Touchette in 2000, the job shop’s location near Houston results in a high percentage of business coming from the oil and gas industry, mainly for drilling components. One of its continuously running jobs for the industry is producing thrust bearing races for down-hole mud motors. Part ODs range from about 3 ” to 6 ” (7.62cm to 15.24cm), with tolerances as tight as ±0.001 ” (0.025mm).

Courtesy of Renishaw

The Equator gaging system from Renishaw uses touch probing to find the center of a thrust bearing race and then scans the part surface to complete the measurement cycle.

Initially, the 150-employee company machined the races on two lathes, with one or two workers manning those machines and manually transporting parts back and forth as one lathe machined one side of a part and the other machined the other side, explained James Wardell, CNC programmer. Conroe Machine later purchased a FANUC robot to transfer the parts between machines and added a second robotic turning cell to increase throughput. The shop sends the semifinished parts to be case-hardened to 65 HRC at a depth of 0.070 ” (1.7mm) before finish turning.

Measuring the parts, however, was done manually with calipers and a bore gage. “We weren’t even inspecting the ball radius because there was no way to do that manually,” Wardell said. In addition, because cycle time was as short as 98 seconds, the operator could inspect only every fifth part. “This scenario was not accurate enough,” he said. “We wanted 100 percent inspection on the races. We needed a more reliable system.”

To improve part quality, the company decided to rough the parts on the two existing turning cells but create a fully automated cell for finishing, including part loading, cutting tool compensation, post-process measurement, part engraving and boxing and palletizing the parts.

Courtesy of Renishaw