Shop Solutions: High-Tech Turning Wins Race, Parts Business
Tony Woodward founded Woodward Machine Corp. in 1978 in a Maryland/Washington DC suburb, as a job shop specializing in race car fabrication and general repair. In 1980–1981, he dreamed up a rack-and-pinion steering for dirt track stock cars and started producing it on manual equipment, mostly salvaged from scrapyards and rebuilt. The only new machine in the shop was a Bridgeport.
Over the next several years, Woodward added a great many new products—mostly turned workpieces—to its line of steering components. Woodward was pretty hardheaded, but it had begun to sink in that his labor-intensive technology had its limits, so in 1991 the company bought a used Ikegai FX20N turning center to help with their round parts. Woodward spent months teaching himself CNC programming from the Fanuc manuals, and finally there came an evening where he and his wife Gloria found themselves eating takeout while the machine made parts all by itself.
In 1993, Woodward relocated to Casper, WY where the facility has grown to 15,000 ft2 (1393 m2) from 5000 ft2 (464 m2) through expansions funded directly from earnings. Woodward has a staff of 10, for the most part single moms who have retrained for careers in industry. Products are race car steering components, including gears, racks, needle bearing universal joints, collapsible safety steering columns, and steering wheel quick releases.
Woodward manufactures its own hydraulic power steering in-house, including the hypersensitive directional control valve. Virtually all other systems marketed for racing use OEM valve components. Woodward is one of relatively few companies in the world who actually makes those parts.
“We machine our gears and valve components from 41L42 and 41L50. Typical part size is from ¾ to 1 5/8" [9.5–41-mm] diameter by up to 6" [152-mm] long. Although we eventually grind these parts to size after hardening, some of them require intermediate operations such as hobbing and milling, which absolutely must start with an accurately turned and centered workpiece. Just about all our parts have to be held within 0.001" [0.03 mm] on the diameter right from the first operation. We do all our turning with cermet inserts and find that with the Hyundai WIAs we can run near the upper limit of SFM, which is where those inserts really shine. The harder grades of cermet are vulnerable to thermal shock, so we turn steel dry,” Woodward said.
A typical part machined on the Hyundai WIAs would be a 3" (76-mm) diameter steel part turned from a slug like the pull ring for a NASCAR steering wheel quick release unit. “It’s quite thin, with less than 5% of the material left after machining. The rest is chips. For an old lathe hand like me there are few things more satisfying than being able to rip steel off to the absolute limits of the holding power of the chuck, without chatter and without compromising the finish or accuracy. The Hyundai WIA’s will do that in spades,” Woodward said.
For bar work, the operators change-out liner bushings and chuck jaws, download the program, touch off the tools, graph it and go. For second operations, they’ll rebore the jaws first. In the interest of speed, Woodward doesn’t get too upset if a few parts are sacrificed while fine-tuning the offsets, at least in the initial stages of the part. In a job shop, it would be different, but here if they get 495 first-operation parts instead of 500 it doesn’t matter. The convenience of the Hyundai WIAs has definitely allowed shorter runs than was the case with their older turning centers, and that is a big plus.
Woodward turns the bearing trunnion (also known as a bearing “cross”) for their universal joints directly to finished size from a 6150 near-net-shape investment casting pre-hardened to Rc 60. That hardness requires straight ceramic, also without coolant. The finish and tolerance are what you might expect for a 3/8" (9.5-mm) inner bearing race with zero radial clearance. Since 1989 they had been manually hard-turning this part using a highly modified chucker. The main obstacles to holding close diameters in dry hard turning are the thermal effects and the high concentration required of the machinist.
Recently, the motorsport divisions of several major European car manufacturers adopted Woodward u-joints. Once the sales of this product grew beyond NASCAR and related American racing, Woodward’s production began to fall behind. "Since by this time we’d already had four Hyundai WIA L210s working beautifully for five years it made sense to investigate the broader Hyundai WIA line. We decided on a KIT-450,” said Woodward.
The Hyundai WIA KIT450 is a compact CNC lathe featuring gang-type block tooling, which is well-suited for processing small diameter, high-precision parts. “After a day and a half of tweaking the toolpath and coolant dwell time, I had the new KIT-450 holding ±0.00013" [0.003 mm], which was above my expectations. The next day, the regular operator applied a few more tricks and was easily holding ±0.00010" [0.0025 mm]. After establishing the edge life, which is much longer than before, they now have it down to somewhat tighter than that, and the dimensions are honest and the finished journals have no taper or waviness. I should emphasize that this is being done with plain ceramic inserts costing about $1 per edge, not PCD,” said Woodward.
Considered purely by itself, the part cycle time compared to the old method is about the same, except that, of course, more cuts are taken in the same elapsed time. The real improvement is that the scrap rate due to thermal effects has gone from over 5% to virtually zero and nobody gets tired. At the end of the day, you have about 50% more parts, all of uniformly high-quality, and this can be repeated indefinitely on the Hyundai WIA KIT-450s by any of the Woodward operators, with complete confidence in the process,” said Woodward. ME
For more information from Hyundai WIA Machine Corp., go to www.hyundai-wiamachine.com, or phone 201-636-5601.
This article was first published in the February 2014 edition of Manufacturing Engineering magazine. Click here for PDF.
Published Date : 2/1/2014