February 2008 Edition

QM Enterprise Metrology Sleuth

Things we know aren't true

(And the bottlenecks they create)

It was 3 p.m. on a cold Monday in January and Sleuth had a feeling his iPhone would not be ringing. Last week was hellish and next week he had more than plenty on his calendar. So, what the heck. He plugged in his earphones, threw his feet up on the desk, and dialed up his favorite iTunes, starting with Crystal Gayle warbling Don't It Make My Brown Eyes Blue. To enhance the experience, he logged into Google images and brought up a slide show of some of his favorite tropical vacation spots.

You know what happened next. The instrument of Sleuth's pleasure became a torture device. Quite out of the blue Sam Atkins, a manufacturing engineer over at Parts 'R' Us, was bellowing into his ears.

"Sleuth, you've got to get over here right away. I've got big problems."

Sleuth came down from his flight of fancy, pinned on his permanent visitor's badge and headed over to his best customer. He found Atkins in the new aerospace parts manufacturing cell, where the guy had been living 10 or 12 hours a day, six days a week.

"Sam, I thought you had your manufacturing processes all ironed out and you were knocking out those little machined air frame components right and left."

"Sure am," he confirmed. "I'm making them so fast the inspection guys can't keep up with me."

"So why don't they get some more capacity over there?" Sleuth said.

"They're planning on it, but probably not what I need. We just bought a big, precision CMM and Parts 'R' Us is not likely to be dealing out those kinds of bucks again any time soon. You see, we cut these composite parts in families, all on a single fixture. We tried to refixture them individually on a smaller CMM, but they lost their shape and we can't measure them that way. So we have to haul the whole fixture over to the measurement room and wait for time to free up on the big machine. That does not happen often because we also have some contracts for big, expensive air frame parts."

"So measure them right on the machine," Sleuth said with conviction.

"We're trying to get that going now with a portable arm, but we still have to wait for one of the guys who knows how to do it to get over here with his equipment. Then when he does, it takes quite a bit of time to set up and measure more than a dozen of these parts at a time."

"Do the machines in your cell have spindle probes?" asked Sleuth, who was beginning to suspect that Atkins was trying to drag him into a pitiful game of "yes, but."

"Yes, but they're just too difficult to use. I tried to write some measurement routines using the CNC's probing macros and then customizing them. I never got as far as locating the parts on the machine, let alone measuring them."

"Hmmmmm . . . ," said the Sleuth. "Have you thought about using real Metrology Software, the same kind you use on your CMMs, to generate measurement programs you can use on your CNC machines?"

Sad Sam Atkins shook his head and looked down at his feet and mumbled, "Yes, but that'll never work. Not here."

Sleuth hated playing yes but. He held his breath until his eyes started bulging and then he launched his counter-attack: "Of course it will work. Accuracy won't be a problem for these parts and since you are measuring them in place, you won't lose any of your error budget like you would if you had to move or worse yet refixture them.

"The software doesn't cost that much. The programs can be downloaded from a server to your CNC systems and the data captured and analyzed at the server — so your machine will still spend most of the time cutting parts. And the same machine measurement server can handle all six of CNC machines in your cell, so you only have to buy one basic system.

"And programming is done offline using the CAD model — but you don't have to learn how to do that because your CMM guys already know how to do it."

"That's the problem," Sam Atkins intoned morosely. "The Quality Manager won't let them. He doesn't want anything to do with measuring parts on the same machine that made them."

"Yikes," thought the Sleuth. He was toast. The old "can't-measure-parts-on-the-machine-that- made-them" wives' tale had raised its ugly head. "I've had it for today, Sam."

"I'll walk you to the door," he muttered.

While they were walking to the door, Sleuth saw something very interesting. Over in the far corner of the shop, towering over the Parts 'R' Us V.P. of Manufacturing and several others, was a gigantic, newly acquired, million-dollar-plus Aqua Flash X waterjet cutting system.

"What are they doing over there?" Sleuth asked.

"That's one of my problems. Those two guys with the portable arm, who should be measuring my parts, are setting up one of those 25-foot structural beams to be cut on the Aqua Flash. They can make an expensive part in about two hours, but it takes them about the same amount of time to align it properly before they get started."

He continued: "The Veep stuck his neck way out to buy that equipment. So the portable arm guys have dropped whatever they are doing to run over there every two hours.

"Wait just a minute," said the Sleuth, turning back to Sam. "I think I've just solved your problem." And he did.

A month later, Sam was measuring parts on his CNC equipment using server-based programs written by the guys in the Quality Department. Parts were manufactured and measured on the same machine, then shipped immediately to a happy customer.

The Quality Manager didn't want any part of it at first but he was totally overruled by the Manufacturing V.P. When the Sleuth came in to consult on another matter, Atkins asked him what he said to the Veep to turn his problem around so quickly.

"It was a pretty simple sell. I asked him how he would like it if he could manufacture one of those composite beams on the Aqua Flash every two hours and 20 minutes rather than one every four hours. He said he would like that a lot and asked how that was possible."

I explained he could use the same on-machine measurement software you were hoping to use — this time not to measure the parts but to align them. It was something that could happen pretty quickly I added, since the CMM guys already knew how to write the programs. And so it came to pass. Convincing him that you could use the same technology on your machines was a piece of cake.

That day as Sleuth rode off into the sunset, music streamed from his iPhone to his car stereo. Sleuth's play list started with It Ain't Necessarily So, followed by Garth Brooks' rendition of I've Got Friends in Low Places.

 

 

 

 
EM Sleuth is sponsored by Wilcox Associates Inc. (www.pcdmis-ems.com), part of the Hexagon Metrology Group and makers of PC-DMIS measurement software.

 

 

 

 

 

 

Contributors to this article include Steve Logee, business development manager, Wilcox Associates, slogee@wilcoxassoc.com; Rob Fabiano, Sleuth illustrator, rfabiano1@cox.net and Joel Cassola, writer, jocas@cox.net.

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