What you get with the above combination is a very happy customer and a universal grinder that outperforms the competition by virtually every measure. The result? Ultra-precision, guaranteed quality parts and components for the most demanding customers, those in commercial and military aerospace. Figure 1
Tom Molnar, president of Lee’s Enterprise, explains that his company is unlike other aerospace job shops. “Just about everybody has turning and milling,” he says, “and a few may have grinding capability, but almost no one has turning, milling, grinding and gear cutting in-house. So we don’t have to send our parts out to get some of the key features made elsewhere, such as grinding and gear cutting. We are able to do almost all the critical operations ourselves. Which gives enormous control over our processes, our quality and throughput.”
First, You Get Busted
Molnar’s father started the company 38 years ago. He came from Hungary and was a machinist by trade. He worked for a variety of companies, including Case (previously J.I. Case, the tractor builder), and he eventually worked for North American Rockwell doing aerospace work. He then started his own company in his garage as a job shop. At some point he got busted for having a machine shop in his garage in a residential neighborhood. “This is how many businesses get started; you work out of your garage or basement until somebody complains, you get busted and then you’ve got to go legit,” says Molnar.
Today the company employs 47 and operates out of 25,000 square-feet in two buildings. Lee’s Enterprise has been doing aerospace work 100 percent of the time. The company has a full inspection department with CNC and manual CMMs, four full-time inspectors and a QC manager.
Molnar says the parts they make are all aircraft applications. These devices open and close critical elements: actuators for cargo doors, for example, or flight lock actuators for opening and closing entry and exit doors, actuators that control rudder trim, that go on thrust reversers, or that control wing flaps — they’re all definitely flight critical parts.
“Our typical part has two or three ODs that get ground, then probably some milling on a feature and probably a gear or spline,” he says. “The longest would be 14” to 15”, but most are in the 3” to 6” range. The diameters vary. For example, we make some electrical rotor shafts that get pressed into a rotor stack and then dropped right into a motor. That shaft is going to be 1” in diameter or smaller. Some of the housings and the parts, however, where I benefit most from our Studer S33 1000 are slightly bigger. These might be 6” or 7” in diameter.
“One part in particular has got a couple of 2-3/4” IDs and a 3-1/2” OD. This housing is about 1-1/2” long by 3”. It’s like a big donut — a large bearing race on the OD, and two bearing races on the ID and then a big gear goes through the middle. There is a counter bore on each side with a precision 0.0005” bearing that gets pressed into each of the counter bores. We do this housing in two setups: We do the OD and two IDs from one side, then flip the part over and do the third ID. We probably could build a custom fixture and knock out all four operations in one shot. We just haven’t done that yet, but I’m sure it’s possible.”
Steel is 90 percent of the material Lee’s processes, typically carburizing steel or nitriding steel, which is the material used in gear making. There is a preponderance of 9310 and 4340. There is usually one or two heat treats per part, plus shot peening, nitro edging, and some exotic plating. Many of Lee’s parts go out of the shop four or five times for an outside process that is chemical- based or heat-treat based, not for any kind of machining. All suppliers have to do that because suppliers all have contracts with large aerospace first-tier suppliers. This would include heat treating, plating, nondestructive testing (NDT) and so on.
“All the suppliers we and others like us have to be NADCAP approved,” Molnar says. “This is like a quality organization that goes around and audits all these processors. Our prime contractors, the Boeings and Lockheeds, will stipulate on their orders that you have to use a NADCAP approved processor. The processes that we send out are processes that 99 percent of all shops like ours would have to send out. If we could do heat treating in-house it would be awesome, because virtually every part we make has to be heat treated; however, the costs of setting up in-house heat treatment would be absolutely prohibitive. To have those kinds of vacuum furnaces and testing equipment would be an investment in the millions of dollars.” Figure 2
Selecting a universal grinder
When Molnar started looking for a new grinder in 2009 he wanted a machine that could do the OD work they were already doing — only faster and more efficiently. Most important, however, he was looking for a machine that could do ID grinding as well. At the time he was looking for a high-end, top-of-the-line universal machine, and he had it down to three different machines.
“We looked at an Okamoto to do ID work,” he says, “but that was a limited machine in that it would only do ID work. Frankly, I didn’t have sufficient work for an ID-only machine. So if we went that route that machine would see only part time use."
“Then it came down to a Kellenberger and the Studer S33 1000 from United Grinding (Miamisburg, OH). We looked at them both very carefully, and went back and forth, arguing the merits of both machines. Ultimately we chose the Studer. UGT worked with us on price. Remember, in 2009 machine builders were eager to sell machines, and here we were starving to get one. We talked to customers and other suppliers and everybody had a very high regard for Studer — the Rolls Royce of grinders, one said. It became clear to us that everyone thought the Studer was the best machine you could have. In the end we decided we wanted to go with the very best. And we’ve been nothing but happy about the decision.” Figure 3
The Studer provides some serious advantages. Lee’s Enterprise runs some parts that require grinding two or three IDs and typically ODs as well. Many of the gearbox housings require both ID and OD grinding, with the IDs and ODs concentric within 0.0005”. Previously when they were running ID work they used an older manual universal machine, and they couldn’t do ID and OD work in the same setup. They had to rotate the part and re-indicate every critical feature. So when they’d run jobs in the past it would be in series, one operation after another. They’d set up the machine and do one ID, then stop, re-indicate, then go to the next diameter, stop, re-indicate, and then the next and so on. “When you’re running 30 or 40 parts, it took a long time to get the first part off that had all the features done. With the Studer S33 1000 CNC we can fixture a part, indicate once, and the machine will come in and do the ID, then swivel around and grind the OD, and we have concentricity basically of zero. No change over time, no indicating time, the throughput is higher and the parts are much more precise. So it’s not just speed we’re achieving; we’re actually making a better part, time after time.” Figure 4
A Look at the S33
The S33 clearly demonstrates a full commitment to tailor products around the explicit requirements of customers. It is equipped with latest generation of high frequency internal grinding spindles. The spindles turn this universal cylindrical grinder into an effective internal grinding machine with high torque and over a large speed range. The machine can grind with speeds up to 120,000 RPM, thus allowing the grinding of bores down to 0.625". A "flat" torque curve on this type of spindle will mean fewer spindles over a larger speed range. This reduces setup time and investment costs. Figure 5
The basic wheelhead can be indexed at 0o or 30o for straight and angular plunge grinding. A universal turret wheelhead swivels automatically, permitting external, internal and face grinding of workpieces in a single setup. The machine features a high precision Hirth coupling B-axis with a 1o indexing capability. The turret head repeats in .08 arc seconds. This allows for extremely accurate ID to OD run-out and concentricity.
Digital direct-drive, three-phase servomotors with 1.5” diameter prestressed, precision ballscrews power the X- and Z-axes. The direct drive spindle turret wheelhead is powered by a 15 HP motor and has high-precision roller bearings for precise, high-resistance, maintenance-free operation. Infinitely adjustable speed control to 3200 RPM. Workpiece spindle, with high- precision roller bearings, handles grinding between dead centers as well as live grinding with revolving spindle. Precision control permits fine adjustment of cylindricity during grinding operations to +/- 40 µm.
Tolerances and Surface Finishes
“We’re typically running an 8 Ra to 16 Ra surface finish,” Molnar says. “Our customers usually ask for a 8 Ra, and I think the machine can do better than that. Our tolerance range on shaft parts is 0.0002” or 0.0003”, and on ID work we’re holding 0.0004” to 0.0005”. The Studer is solid, rigid and extremely repeatable."
“We still have the older grinders here in our shop,” continues Molnar, “and they run every day. However, if a job has a combination of OD and ID work, it automatically goes to the Studer. Basically, our most critical and crucial parts go on the Studer. We trust that machine more than we do the other grinders. This is not to say I don’t trust the other machines because I do — I run them 90 hours a week. But if I had to choose a machine to run our most crucial job, it would be on the Studer. I have a lot more confidence running parts through that machine. I know how long it’s going to take and I know what I’m going to get. We have significantly better quality in our ID grinding with the new S33, and it has a much faster cycle time and this obviously increases throughput.” Figure 6
Molnar explains that they were running two shifts, and then brought it down to a single shift — not because they were slowing down, actually they were getting busier. In fact, some of his employees work 50 to 60 hours a week. He has employees that come in early and employees that come in a little later in the day. This unique arrangement is what he calls a “spread shift.”
“My shop is open from 3:30 a.m. to 7 p.m.,” Molnar says. “We’re trying to be more flexible with our employees, and it’s something we’ve been doing for the last five or 10 years. In order to attract the best talent that we can and keep it, we're trying to allow people a little more flexibility to tend to things that they need to take care of in their lives. I’ve got quite a few guys that are single dads, and they have to take their kids to school in the morning, so it’s hard for me to say, ‘you’ve got to be here at 6am,’ when they have to take their kids to school at 7:30 a.m., so these guys don’t start until 8:30 a.m., and then they stay later in the day.
“Then I have five or six employees who drive up to 70 miles one way and these guys are starting at 3:30, 4, or 5 a.m. because they have found the commute at that time of the morning can take an hour, whereas if they started at 7a.m., it would take two hours."
“So over time we’ve tried to make accommodations for our employees, and we’re repaid with employee loyalty, and guys who are willing to work hard because they see we’re willing to work hard for them. This is really a unique work arrangement, and I know some people when they first begin to work at Lee’s, and see people coming and going, they are shocked to realize they have that kind of flexibility. Last year I hired 14 employees, so I went from 33 to 47 in 2011. Of the other 33 that we had prior to last year, I’d say 70 percent of them have been with the company for 10, 15 or 20 years. So we have very, very low employee turnover, and I think some of that is because we’re willing to work with our employees’ schedules and needs.” Figure 7
Service Beyond the Call
“United Grinding really did a great job in getting the machine to us,” Molnar adds. For tax purposes Lee’s wanted to make sure they got the machine before the end of 2009. UGT jumped through some pretty significant hoops to make this happen. They flew the machine to Molnar’s operation — it didn’t come over on a boat, it came by cargo plane at a pretty good cost to UGT. “The machine was delivered on December 28, 2009,” Molnar says. “So they really went out of their way for us, which is something I will not forget, and I really appreciated."
“United Grinding provides all the service on this machine,” Molnar says. “The only guy who’s ever worked on our machine is Ray Wyland, and he’s a UGT employee. He also installed the machine and trained my people. The sales guy who worked with us, Jim Reynolds (DMARK Corp.), is absolutely top-of-the-line. Everyone we worked with on this project has been the best, and they’re all 100 percent service-oriented. They’ve redefined service and customer satisfaction and taken them to an entirely new level.”