May 2011 / Volume 63 / Issue 5|
'Softening' hard gage costs
By Alan Richter, Editor
Billed as a “radical” new alternative to traditional hard gages that are dedicated to in-process measurement of specific parts, the Equator gaging system from Renishaw Inc. is based on a scalable and adaptable “parallel kinematic” structure that enables high-speed scanning, rapid moves between features and a high level of point-to-point repeatability, the company reports.
In a product-prelaunch application, Meyer Tool Inc., a manufacturer of hot-section jet engine components, was able to eliminate at least four hard gages in a work cell, according to Beau Easton, the company’s quality manager. He noted that each hard gage can cost up to $20,000 to design, build and maintain, and Meyer Tool has more than 100 such gages.
Courtesy of Renishaw
The parts manufacturer primarily uses a work cell-based, comparator-type system with pneumatic digital probes for in-process dimensional measurement of parts on fixed nests. “The Equator allows us more flexibility in the cells because we don’t need as many probes or as many different individual nests,” Easton said, adding that each probe costs from $500 to $600.
Meyer’s internal Orion SPC (statistical process control) data management system works in conjunction with Renishaw’s Modus software, which drives the gaging system. Equator systems are available with two levels of software: a shop-floor version, which allows DMIS (dimensional measurement interface specification) programs to be executed but prevents operators from making modifications, and a programmable version that enables creating DMIS programs. Meyer has the latter version because the majority of its programming is done offline, with coordinate measuring machine programmers using Unigraphics 3-D part models, Easton explained. “We like to work most of the program out that way and then go in and do the physical simulation.”
When switching between parts with the Equator, Meyer uses precision plates that have a couple of nesting points for the part to rest on and function similar to a quick-change tool, according to Easton. “You just pop in the plate, hit go and the Equator will find the part,” he said. “It takes 20 to 30 seconds to swap plates instead of going and getting another fixture, putting probes in and remastering.”
With the gaging system, there is no need to remaster after every part change, but Meyer does remaster, or reverify, every 3 hours to compensate for changes in the plant’s temperature. Although the shop is environmentally controlled, the temperature can fluctuate slightly as machines warm up and cool down and workers enter and leave.
By enabling a manufacturer to quickly switch between parts, the system is suitable for flexible manufacturing processes or accepting parts from multiple machines, according to Renishaw. “The way we run right now, I have eight machines tethered to one Equator,” Easton said. “Inspection is well under our actual grinding and machining times, so it’s not a bottleneck.” He added that Meyer also added an Equator, which costs about a third the price of a CMM, to its waterjet facility and is programming a third system.
The gaging system measurements at Meyer are correlated with those from a CMM, using a CMM-calibrated master part. “The master part sets the values the Equator expects to find inside its measuring envelope while the software automatically applies the compensation values from nominal taken by the CMM,” said Bridget Nolan, SPC manager. “It must check within 10 percent of allowable tolerance from nominal.”
Easton explained that Meyer settled on 10 percent because that provides an appropriate 10:1 gage-to-tolerance ratio. “We’re making sure our gage is 10 times more accurate than our machining process,” he said.
For more information about Meyer Tool Inc., Cincinnati, call (513) 853-4400 or visit www.meyertool.com. For Renishaw Inc., Hoffman Estates, Ill., call (847) 286-9953 or visit www.renishaw.com.
Courtesy of Equipois
“Hello boss, I won’t be able to come in today because I injured my left arm at work yesterday,” reports your top metal finisher. Performing fine metalworking and other manipulation tasks using outstretched arms for long periods of time causes worker fatigue, discomfort and possible injury, according to Eric W. Golden, president and CEO of Equipois Inc. Those tasks include manual drilling, grinding, engraving, part gaging, assembly, probing and soldering.
To overcome those problems, the company developed the x-Ar exoskeletal arm that attaches to a worker’s forearm and supports the arm through its range of motion or holds it steady in place. “Activities where people have to work with their arms outstretched are very tough on the shoulder,” Golden said. “Over the course of months and years, it’s pretty common for people to have to undergo surgery or at least take time off. Our goal is to eliminate those sorts of problems for the worker.”
He added that the device, which has a weight support capacity of about 14 lbs., enables workers to exert less effort, effectively increasing their stamina and strength. “If you don’t get tired when you work, it means you can be a lot more effective and precise,” Golden said. “You can work faster for longer without putting your body at risk.”
The device’s cuff that an arm slides into is covered in a soft material similar to the cast material hospitals use. The cuff can be exchanged for different workers, Golden noted. Two cuff sizes are available. “The two sizes cover a wide range, all the way from a very petite woman to a very large man,” he said.
Because the spring-driven device is mechanical, it doesn’t require a power source or any computer technology. “We help humans rather than replace them with something that’s automated,” Golden explained. “One of the underpinnings of our philosophy is that there is no better tool than the human brain powering human fingers. For a lot of tasks, if you try to intervene by putting a motor or computer in between those two, you won’t be doing as good a job as a human would do.”
The moving parts of the x-Ar arms, which weigh about 5 lbs., attach to a chair, bench, table or mobile stand and shadow a worker’s actions, according to Golden. “It should almost be invisible to the user.”
Golden noted that he expects x-Ar’s price to be from $2,000 to $3,000, depending on the quantity and complexity of the mounting scheme.
For more information about Equipois Inc., Los Angeles, call (866) 601-2070 or visit www.equipoisinc.com. CTEAbout the Author: Alan Richter is editor of CTE, having joined the publication in 2000. Contact him at (847) 714-0175 or email@example.com
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