FULL SPEED AHEAD

Mike Langlois, owner of Aero Precision Machine (Julian, NC) owned and operated his first lathe when he was thirteen years old. He was making his own model airplane parts to keep the motors running at higher horsepower and rpm, and even selling them internationally to other model airplane enthusiasts. He eventually ended up getting a pilots license and buying an early model Beechcraft.

Mike hangers his airplane just a half a mile from his home in Julian at the local airstrip at Causey Airport. After touring the small airport, we learned that his good friends Charlie and Winfield Causey provide chartered flights and aircraft maintenance, and run a separate company right there at the airport that sells high-precision aircraft parts.

In the early 1990s, Mike decided to setup a shop to specialize in close tolerance aerospace parts. Another friend from Pennsylvania, Henry Nelson, recommended that he consider a colleted-spindle turning machine and suggested that he look at some lathes. It was researched and agreed that when gripping the part within the spindle closest to the spindle bearings you would achieve a better concentricity, better surface finish, and therefore put out a higher precision part.

Mike purchased a used Hardinge HNC lathe and began making aircraft landing gear bushings. His wife and two sons joined the business in 1996 that has now grown to 10 employees in about 8,000 sq ft of shop space – and is still growing. Aero Precision Machine now produces parts for the aerospace, defense and pharmaceutical industries. They handle mostly smaller parts in diameters up to 10 in, but their sweet spot is the ¾ in to 2-1/2 in range.

Over the years they've built their entire turning capabilities using collet-ready spindle lathes for high-precision turning, including a QUEST® 10/65 Super-Precision® HydroGlide® turning center. "It's all about accuracy, says Mike. "We made the decision to be a collet shop. Down here that is kind of a rarity. Everybody wants an 8-in chuck machine. Our parts are often more fragile, have a thin wall, or a close tolerance. Typically with aircraft parts such as landing gear bushings we need to hold a .0002 in to .0003 in tolerance on the OD and ID. Early on we decided to go with the collet-ready spindles, and I have never regretted that decision. In our shop, the chuck is the workholding device of last resort. Using a collet I can spin the part up faster, turn it at high rpm, and the concentricity and the surface finish are better. Plus, the setup is quicker."

"This was one of the features that sold me on the direct-drive rotary system," says Mike. "One of the advantages of the indexer is the collet-ready spindle that lets us use our existing supply of collet type workholding. We didn't have to buy anything. We use mostly 16C collets in this shop and the DD300 rotary system uses 16C collets." The DD300 combines high torque, high speed and high accuracy in one rotary system. It doesn't have any gears, so there is no wear over time. By high accuracy, we're talking ±3 arc-sec accuracy, ±2 arc-sec repeatability and .0002 in maximum runout.

This wheel-style part, made from 2024 aluminum, is used in the pharmaceutical inspection process. The customer's part to be inspected is located against each of the six drilled surfaces. Back at Aero Precision Machine, they turn the outside diameters, face and cut it off on turning lathes. Then the part is slipped on a Sure-Grip® expanding collet in the DD300 rotary system for machining on a Bridgeport XR1000. They ball mill the twelve outside shapes, center drill the part and then drill the six ports true to the center position.

Fast, super-precision positioning is accomplished with the gearless, direct-drive rotary system with rapid indexing from hole to hole. Then they come off the center for a counterbore, drill and tap, then slit with a slitting saw and finish up with an end mill.

"We used to run this part on a different brand 5th-axis indexer until we purchased the direct-drive rotary system," explains Mike. "We see a 30 percent reduction in part cycle time due to the ultra-fast positioning speed of 1500 deg per second, and a cutting speed of 600 deg per second of the DD300 direct-drive system. We are also seeing more consistent repeatability. When we used the other-brand indexer to make the parts, we had to make offset changes on the machine tool nearly every other part to keep the part within tolerance. The part's pick-up contours have to be held to within .001 in on diameter and at a 60 arc-sec angular position. The combination of the XR1000 machine tool and DD300 rotary system made holding both tolerances as simple as 'falling off a log.' The XR1000 has thermal compensation on the Z-axis, so holding diameters on parts being processed on a DD300 requires far fewer offset changes."

According to Mike, getting jobs from the pharmaceutical industry is highly based on supplier performance. Pharmaceutical part assembly and inspection is all about high speed and high volume, and they do not tolerate parts in their facility that are not 100 percent to spec. Many dollars are at stake if the line has to be shut down because of a malfunction in their production process. "This means that we as a job shop have to establish a reputation for 100 percent quality and consistency," remarks Mike. "Every single part has to be individually inspected."

"This direct-drive rotary system is a nice asset to our company and fits perfectly in our 16C collet shop," adds Mike." It has more speed and more accuracy than anything I've seen on the market. In this era of multitasking machines, and especially for jobs that require a heavy-duty milling spindle, the DD300 could be the device that opens up the frontier of turning on a mill."

Aero Precision Machine, Inc., 6024 Smithwood Road, Julian, NC 27283, 336-685-0016, Fax: 336-685-9195, ml@aeroprecisionmachine.com, www.aeroprecisionmachine.com

Hardinge, Inc., One Hardinge Drive, Elmira, NY 14902-1507, 607-734-2281, Fax: 607-734-3886, www.hardinge.com.