PHILPSBURG, PA — Fred Grauch, owner of Grauch Enterprises says his shop does just about everything: “There’s very little we won’t try, especially since we’ve acquired our two newest multitasking turning centers, a Hardinge QUEST 6/45 and a Hardinge Super-Precision QUEST 10/65, from the Hardinge Group (Elmira, NY). The guys at Hardinge say these QUESTs will do hard turning, run right through fully hardened material, and I have no doubt that these bad boys will do it.”
Typical machined parts produced at Grauch Enterprises include more than 650 different items for the DOD. They’re all called “knobs” for
one reason or another. The specific part used to justify an investment in new turning technology, more specifically the two Hardinge
QUESTs, was actually a switch-bolt for a “Ma Duce”. The Ma Duce or M2 .50, is a 12.7 mm caliber air-cooled machine gun (World War
II era), which is typically vehicle-mounted or set on a tripod and belt-fed. The switch-bolt technically is a “miscellaneous” part, but
someone thought it looked like a knob and put it on the DOD parts list under 5355 (knobs).
To machine these complex parts in high-volumes, Grauch upgraded his shop with the purchase of a Hardinge Super-Precision QUEST
10/65 (during IMTS 2006), and followed that up within six months with an “unplanned” Hardinge QUEST 6/45. “Most of our parts are an
inch in diameter or smaller,” he says. “The Super-Precision QUEST 10/65 goes up to 2.5” through the spindle and that really increased
our capability compared to our gang-style tooling machine, which is 1.065”. Even the QUEST 6/45 goes up to 1.625”. So both machines
have really increased our ability to turn larger diameters.”
Volumes? He takes out the calculator, and in a matter of moments says, “188,943 parts generating over $2 million, sales from September ‘06 to September ‘07. And it’s the two Hardinge QUESTs turning out most of those parts, and they’re hungry for more.”
During the 2006 IMTS, Grauch and team visited the Hardinge Group exhibit seeking a new solution for the Ma Duce switchbolt. “When we first showed the switch-bolt to the Hardinge engineers, saying this is what we want to make on the Super-Precision QUEST 10/65, they said, ‘Well, this uses everything on our machine, which includes the C-axis, the Y-axis, X/Y combination, C/Y combination, the sub-spindle, the live tooling, everything. We haven’t seen something like this in a long time. It’s going to be a challenge’.”
Actual cycle time: eight minutes. So much for the challenge. This is a good thing, as the DOD ordered more than 9000 of the switch-bolts.
Turning the switch-bolt (or knob)
Grauch explains the machining sequence for the Ma Duce switch-bolt. The barfeeder feeds material out to a given length. They use a roughing tool to rough the front end because the barfeeder leaves about 0.010” to 0.020” to clean up the front finish. Then they’ll rough down the outside diameter and taper to the back smaller diameter.
Next is the slot. It is angled on each end, so they’re actually doing a Z-axis/Y-axis move: As they’re coming from front to rear,
they’re also moving out, going straight across and then going back in. The mill slot through the front is what actually guides the bolt action loading the ammunition.
Next, switch tools and come in with a parting tool and groove out the backside of the part, making it smaller than the front side. They then use one drill to spot and create the locating holes which are opposite one another. (The hole used to locate the switch-bolt determines which side the ammunition feeds through the machine gun, allowing them to be mounted side by side.)
A milling operation from the top (X-axis) angles the two sides followed by a radial operation down those sides to allow grease to move through. The part now has two angles on the front edge.
A finish turn cleans the front side and turns the tight outside diameter.
Then they go back with a 45° six-blade chamfer tool, and chamfer (deburr) all the edges. A through hole is spot and drilled. Next they finish hogging out the backside and put in a radius.
Finally the part is ready to be finished on the sub-spindle. Before this can happen the last part, still in the sub-spindle, is removed by a robot arm, which drops the finished part on a conveyor belt where it is then sent to a parts bucket. This all occurs before the sub-spindle picks up the next piece. It’s in the middle of the program for the next switch-bolt that they actually take the finished part out of the machine.
Just a little over eight minutes, start to finish.
The sub spindle again comes up and grabs the next piece, and they part it off. Then they spot the back of all three holes and ream the two locating holes 0.201”, ±0.0002”, finally facing off the second tight tolerance diameter.
“But the really nice thing — and this is why I love these machines — there are many times when you think you’re going to have four or five processes,” Grauch says, “and you start with one process and get to the last process, and say ‘Gosh!’ we should have done this as the first step because it’s affecting the last step. Using this program, the part is done. If there’s something that’s just not right, you know it right away, because you have a finished part. You’re not finding out after you’ve made 5,000 parts that there is a better way to do the first operation. With the Super-Precision QUEST 10/65 you can tweak the process, the sequence, as the part runs.”
The part starts off as 2.000” bar stock and when finished, the largest diameter is still 1.811”. The two ODs are -0.001”, and everything else is 0.005”. Hole size is -0.001”, and they hold 0.0002”on these two holes by reaming them. But the main tolerances are the two diameters; they fit very snugly into a Ma Duce.
Grauch admits, “This is just another reason we went to Hardinge: We knew the capability to do this kind of complex job was there; that they had the engineering depth to know if they could make the part or not. If not, they wouldn’t have sold us a machine.”
Long runs/short runs
Grauch reports that for them a small run is 1,500 pieces and a longer run may be 10,000 parts. Right now, to be cost effective, they’re doing all of their long runs on the new Hardinge machines. You write the programs, they run for a couple weeks, and you’ve made 5,000 to 10,000 parts. Eventually, their intent is to put shorter run jobs on the machines because changeover is so short — a matter of just changing the tools (if that).
“We have designated certain tools in certain areas, so the changeover is not that long at all,” Grauch says. “Even if we had to change the entire turret and all the tools, the touch probe for the tooling let’s you just touch them off, and you’re done. It’s so fast, it’s phenomenal.”
Grauch explains that his two QUESTs have two probes. One, the tool probe, mounts on the wall of the machine by the spindle. When you load up all of your tooling, you move the turret back out of the way. Then the touch probe comes down and you manually extend the turret and touch your X and Z positions. That information is loaded directly into the GE Fanuc control, and the machine now knows where each tool is. Then, you just index around; you can touch off all of your tools in about five minutes. Changeover in 15 minutes to a half an hour.
“The second probe, the part probe, is used specifically on the .50 caliber switch-bolt,” Grauch says. “We’re planning on running this at night in addition to during the day, and we have sub-programs where the part probe mounts on the turret and the turret will come every so many parts, say 20, and it will touch the turned areas where we’re trying to hold to 0.001” in alloy steel. It will adjust the offsets in the machine to hold that tolerance, and as we get into production, we can check every 10 parts or five parts — every part, if we want — and the probe will tell us if we need to make an adjustment. It’s all in the programming. During the day, if you have all of your personnel tied up watching other machines, you can load the program that does self-inspection — and the QUEST will inspect itself. But, the main reason we have the part probe is to run the Super-Precision QUEST 10/65 at night, when there’s no one here, lights out, and it just runs very, very precise parts.”
QUEST call home
“We’re shooting to hold 0.0005”, ± 0.00025”, on the .50 caliber switch-bolt,” says Grauch, “which will be assured by the part probe, and the redundant tooling we’ve installed. The QUEST will adjust x-number of times, and after so many cycles, the turning tool will have worn — the edge, for example. The program will now load redundant tooling, and instead of using position One, it will now index to position Five. Whatever tool wears, the QUEST will keep running because it will switch and start using redundant tooling. That same process will repeat x-number of times, and when it continues to go to another tool or shuts down, the machine will make a phone call to say, ‘I need your attention’.”
Grauch says they can put enough material in the bar feed to run for about 48 hours. If something happens — the feeder runs out of material, or the probe says we’re not holding tolerance and it can’t be remedied, the machine will stop and make a call.
“This is all done in the background, in the programming. What will happen,” Grauch says, “is that whatever the problem, it will trip the emergency stop relay. There’s a device that you buy that hooks up to your phone and you program in your number. If the machine gets an error code and shuts down, the relay is tripped and the machine calls the pre-programmed number of whoever is on call, and their phone will start ringing. This doesn’t happen all that often but it gives us complete confidence to load up the Super-Precision QUEST 10/65 and let her rip all night.”
“I’ve had machines that require you to take half the machine apart just to get to something you need to look at,” says Fred Grauch. “But the Hardinge® QUEST® turning centers have plenty of space, they’re designed to be accessible for set-up, operation and maintenance. Plus, they have lightning-fast indexing speeds and the rapid traverse rates, which combined deliver time from cut to turn, or from tool to cut in the blink of an eye. It’s so fast that our shop foreman jumped five feet when she saw the first QUEST running; she thought it was going to crash, like a train wreck. We don’t have anything that fast here. The rapids on the QUESTs are twice as fast as anything we have here. Twice.”
“So now we have matching systems, and can interchange between two Hardinge QUEST turning centers. The Super-Precision QUEST 10/65 is ideal for the Ma Duce switch-bolt job, which we run at nights as well as during the day. The QUEST 6/45 runs days and some nights and handles all of our other parts. Now I look back and say, ‘How did I run this place?'