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Machined Components, Ever-Closer to the Heart



"At one point recently we found ourselves without the capacity to keep up; especially as the family of one part in particular continued to grow, so we started looking," said Dan Reed, owner. "Technology-wise, GBI, the master distributor of the Feeler line, among others, had the right machines for our needs."

R&R's oldest Feeler is about a year, and in all they have four Feelers - two VM-40SAs and two QM-22Aapcs with twin pallets and automatic pallet changers. Other nameplates in the shop include Fadal, Cincinnati and others. But the Feelers are the ones doing much of the really complex medical work, the company said.

Complex Part for Demanding Job
Reed said that of the many parts he runs through the Feelers, there is one part both models of Feeler work together to produce: "There are seven different sizes and configurations of this part, and then there are right- and left-side versions, so together there are 14 different variations of this part in a family. It's made of stainless, and it's used in the ablation of heat tissue for arrhythmia problems. It goes into the body cavity to help repair irregular heartbeats."

Reed said that this part starts out on the VM-40SA as a stainless steel block, 0.750" x 3.250" and when finished on the QM-22Aapc, it's about 0.1875" x 2.500" (or 3" on some). It's 100 percent profiled and looks like a banana: it goes from thick to thin and is a continuous curve. On the VM-40SA, machining the part involves true 3-D milling. The feed rate is 75 IPM, and in first operation they use a 0.625" roughing tool and mill to a depth of 1". In some cases, they've milled one-third of the way into the starting block. At the other extreme is milling the profile: 0.004" to 0.006" per step at a rate of 55 IPM. So the first major operation, creating the perfect profile, is the VM-40SA's job.

Next, Reed said they take the part to the QM-22Aapc and fixture it on the first pallet, radius side up and turn it upside-down. They machine the bottom flat with grooves and holes and slots. Then the part is moved to the second pallet where a third operation (why they needed dual pallets) machines angles and slots at 90 to the first axis. This completes the part from beginning to end.

"The tolerances are 0.002" overall, and in the 10ths on hole positioning," said Reed. "Two thousandths doesn't sound like much, but on this part, with all that we do relative to its size, 0.002" is very tight. The surface finish is around 32Ra. We grit and bead blast the part for stress relief and to achieve consistent finishes. We have to work very closely with the machines on a part of this complexity to ensure we get good parts, one after another. It may look like it's not particularly complex, but it's too complex to finish grind. Our customers check these parts under microscopes, that's how consistently accurate we have to be."

According to Reed, changeover from one size to another in this family takes about 10 minutes. It's pretty much down to calling up another program, correctly placing a new block of stainless, and downloading all the offsets and pressing "Start."

"If we were talking tool life," said Reed, "that would be a different story. I may be somewhat demanding by nature, but tool life is never good enough. I guess I'm speaking generally here. The tool life has nothing to do with the Feelers. As a matter of fact, the VM-40SAs have automatic tool breakage detection. There's a sensor mounted on the corner of the machine and a little macro program in the control. At the end of running a tool, it's automatically sent over to the sensor to see if the tool has been broken or damaged. No, our problems with tooling come from the tooling itself. It's something we'll deal with. But it's like so many other things: We'll get to it when we have time. We never have enough of that (time, that is)."

A Glimpse at R&R's Feelers
The two Feeler VM-40SAs have axis travels of 40" (X), 20.5" (Y) and 19.9" (Z) and rapids of 1.417 imp (X/Y) and 1.260 imp (Z). Positioning accuracy, 0.0003"; repeatability, 0.00012". Way systems are linear (X/Y) and boxed (Z).

Spindle: 40 taper, 10,000 RPM driven by a 25 HP GE Fanuc direct drive motor. ATC is a swing arm-type with 24 tools and a 1.9 sec tool-to-tool change time. Tool weight, 17.5 lbs, max; tool diameter, 3.14", max; tool length, 11.8", max. Control: Fanuc 0i-MC.

The dual-pallet Feeler QM-22Aapcs have axis travels of 22" (X), 16.5" (Y) and 17.7" (Z) and rapids of 1.890 imp (X/Y/Z). Positioning accuracy, 0.0004"; repeatability, 0.0004". Way systems are linear in all axes.

Spindle: 30 taper, 12,000 RPM driven by 5 HP GE Fanuc direct drive motor. ATC is a swing arm-type with 20 tools and a 0.8 sec tool-to-tool change time. Tool weight, 8.8 lbs, max; tool diameter, 2.5" to 3.94", max; tool length, 7.9", max. Automatic pallet changer. Dual pallets, 22.0" X 16.1". Swing arm, cam operated change mechanism delivers 6 sec pallet change. Control. Fanuc 0i-MC.

Intangibles
Reed said there are a number of reasons they chose Feeler. One is the dual pallets on the QM-22AAPCs. Another is chip conveyor systems on both the VM-40SAs and the QM-22AAPCs. A third, the VM-40SA is a good profiling machine, and profiling is critical to the medical part discussed above.

"Then they had something else that's really hard to find," Reed said, "great service and training. GBI offered training, not at our site (they would have done that had we wanted) but at their facility. They have a really remarkable facility, one that most distributors would die for, to say nothing of many OEM machine builders. And the beauty is that we sent our operators there, so our operations here weren't disrupted in any way. This level of training is

something that is difficult to find anymore. I don't know whether it's a case of distributors and builders just not having the money to invest in training or, worse, they just don't care."

Getting the Basics
One of the things that frustrates Reed is that good machinists are hard to find. He said that when he grew up, he knew how to change the oil in his car, change the tires, and knew how to tighten and loosen a bolt. He knew which way water flowed: down hill. He understood how gravity worked.

"This is the simple stuff," Reed said, "but the kids under 25 who come in here, I'm not sure that many can change their own tire. General mechanics is actually problem-solving techniques, and the basics for manufacturing are in the engineering. And that's what's lost on these kids. They don't have a grasp of the simple stuff, yet they immediately want to program the CNCs and run the machines. What they don't understand is that this is only 25 percent of part making. The other 75 percent, understanding tool deflection, the use of proper coolant, using the right machine for the job, this is the big part that sets us apart from most other companies. This is the 'knowing the engineering' part."

Reed said that while his company may be small it has engineering ability of most large companies. Why? Because they go in, get a job, get it done, and their cycle times will be lower than most because others rely on the CNC to do it all. "R&R," he said, "does it using the CNC and engineering, and as a result our cycle times will compete with anyone, especially doing really complicated jobs, like the medical job."

A Philosophy of Clarity
"What we strive for, a kind of motto at R&R, is 'clearly defined requirements,'" Reed says. "That word, 'clearly,' stops a lot of things from starting. When we focus on clearly defined requirements, we tend to do pretty well. Assuming something, or thinking we know what a customer was saying, this is how we get into trouble. If it's clearly defined, 99 percent of the time it's written down."

Reed said that this philosophy applies across the board, from defining employees' jobs and functions to the acquisition of machine tools: "We have a large number of machines from a variety of sources," he said. "Each was purchased for a specific, clearly defined purpose. The same is true of the Feelers. GBI had exactly what we wanted, when we wanted it. And the four Feelers are doing precisely what we purchased them to do. Clearly defined requirements;  when you keep your focus fixed there, you'll usually get what you expect. And sometimes even more, which has been the case working with GBI."

For more information contact:

Kevin Bevan

GBI - Cincinnati

6899 Steger Drive

Cincinnati, OH 45237

513-841-7391

Fax: 513-841-7203

www.gbicincinnati.com

 

R&R Tool, Inc.

937-783-4184

www.rrtoolinc.com

E-mail: rrtool@excite.com

 

 

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