Shop Solutions: Auto Tranny Gear Can't Beat Automated Brush Deburring
HHI Forging, the largest supplier of forged and forged/machined steel components in North America, produces wheel-end, transmission, drivetrain, and steering and suspension components for such transportation industry customers as General Motors, Ford, Chrysler, Toyota, Honda, and Harley-Davidson. HHI has the capacity to do high-, mid- and low-volume production at its nine forging locations, two machining plants and the two other production divisions that fall under the umbrella of HHI Group Holdings LLC (Royal Oak, MI), a company with nearly 3000 employees.
“We’re 80% automotive. We have some of the higher volume forging capabilities, so we have very competitive pricing,” said Christopher Bass, an application engineer who has been with HHI eight years and worked in CNC machining for 35 years. “People do business with us because of the quality of the tooling we build, our quality systems and our capabilities.”
With annual production volume of 500–600 million pieces, HHI needs reliable processes and equipment to help meet the output and quality demands of its customers. The CNC turning process HHI uses in production generates small burrs—raised edges or pieces of material often as small as two to five-thousandths of an inch thick—inside many of the parts. The process of deburring removes these pieces and smooths out rough edges or ridges. Customers provide specific instructions to HHI on the deburring of their parts. A contract may require no sharp edges larger than a specific size or no burrs at all, for example.
HHI Forging uses an automated deburring process with ceramic brushes from Weiler Corp. (Cresco, PA) for high-volume production of transmission parts in some facilities that has resulted in productivity and quality gains. “We have to get in there and ensure with our process that we remove every burr we generate. You look at the quality, and that’s the critical part,” Bass said. “The parts we’re generating are inside the transmission housing, so if burrs are breaking off, they can be a catastrophic failure for that transmission. You cannot have any burrs in a transmission.”
“When you automate and put it in a production line, you’re pretty much guaranteed it’s going to get deburred, so it’s a more controlled process,” he said. “We looked at the process; we’ve never made this type of part before. We realized an automated system would ensure a more robust process and the quality of deburring would be better. We never even considered manual for this product.”
Those types of parts, asymmetrical with teeth and castellations on them, are harder to deburr by hand, especially in a high-volume production situation. The ability to automate the process reduces fatigue and wear and tear on employees, so it benefits safety along with productivity. “When you’re doing the high volume we have, you have to have a consistent system that you can rely on,” Bass says.
The automated deburring system used at the Cloyes production facility was designed and manufactured by Cleveland Deburring Machine Co. (CDMC; Cleveland, OH), so Bass approached that company about designing and creating deburring equipment for the two HHI machining facilities in Bolingbrook, IL, and Fraser, MI, that would be making the transmission parts. CDMC frequently uses Weiler brushes in its equipment and deburring applications. For HHI’s needs in this case, CDMC determined a brush made from ceramic material would provide the lowest cycle time.
At HHI, about 10–15% of the products machined in-house require automated deburring. Of those, the majority are using a deburring process with brushes—mostly Weiler brushes, Bass said.
The two lines that use the automated brush deburring process—in place for about two years now—at HHI’s facilities in Bolingbrook and Fraser each produce about 700,000 units annually. That’s full production of three shifts a day, five days a week.
The automated deburring equipment used by HHI has multiple stations and tools that run simultaneously, so three or four brushes hit different parts of the burr at the same time. The parts are put into one end, and they come out the other end complete and deburred. “So every 10 seconds you index a complete part,” Bass said. “The operator never has to intervene. We want the workers to worry about the process as a whole, not to worry specifically about deburring.”
The brush life is metered based on amperage draw from the motors. When the machine starts to draw more current because the brush is wearing and it takes more effort to remove the burr, it’s time to change out the brush. It’s also key to monitor tool life upstream in the process, otherwise when tooling is allowed to wear too long upstream, the burrs can get too large to be removed under the parameters set for the automated brush deburring process. The expected size of the burrs to be removed is what determines the type and size of brush used in deburring.
“The wheels are quick changeovers typically, in and out in a matter of minutes,” Bass said. “You’re metering tool life, metering brush life,” Bass said. “It’s a living cell, things are always happening, and it’s up to the operator to be aware of it all.”
Anytime that rotating tools are used in production, safety issues can be a concern. The self-contained automated deburring units used by HHI remove that issue from the equation, with the operator safely standing away from the process.
“When you look at it from an ergonomics standpoint and an operator safety standpoint, it’s just tenfold the savings,” Bass said. “You take all of that out of the equation.”
“To me, the difficulty of the part you’re deburring and the volume of parts you’re going to handle are the big issues to consider,” Bass said. “Then look at man versus machine, the wear and tear.”
An automated deburring process will always be the first option for consideration in future production opportunities for HHI.
“We see transmission components as being a big part of our opportunities going forward,” Bass said. “If we are awarded more components that require deburring, then we will stay with automating.” ME
For more information for Weiler Corporation, please go to www.weilercorp.com or phone 800-835-9999.
This article was first published in the July 2014 edition of Manufacturing Engineering magazine. Click here for PDF.
Published Date : 7/1/2014