Braking with Tradition
Story and photos by Scott Rathburn
From CNC Machining Magazine, Winter 2001

Page 3 of 3

OE further reduces costs and speeds turnaround by “production-izing” their machining processes. “We’ve commonized the external features of all of the tools,” Norm says. “We have canned cycles for all three plates, so we can knock those off probably in a tenth of the time it would take the average jobbing shop. Really all that’s left, then, is reverse engineering an OEM sample.”

From the OEM sample, Norm creates the toolpaths in SmartCAM: one to cut the bottom plate, one for the cavity plate and another for the punches. The bottom plate and cavity plate require only two-axis pocketing to cut the profiles of the backing plate and the friction pad, respectively. The punches, however, often require 3D work, because many modern disc brake pads have chamfers on their leading and trailing edges to reduce squeal and chatter.

Nabil Khanania checks the dimensions of a punch for a set of disc brake tooling. The matching cavity plate is shown at right on the machine.

Most manufacturers cut these chamfers after the pads have been molded, but OE takes a different approach. “We mold in the chamfers,” Norm says, ”which is unique in our industry. We take advantage of the 3D capabilities of the Haas to cut the chamfers into the tooling.”

Since all of the cavities in a particular set of tooling are identical, as are all of the corresponding punches, Norm only has to create the toolpaths for one location. This done, he hands off the programming and machining duties to Nabil Khanania and Dan Beaudin.

Nabil has been with OE Quality from the start; in fact, he was the company’s first employee. “I met Norm when I was taking the CNC course at Humber College” (a local community college), he explains. Dan is a graduate of Humber College, as well, who was recruited by Nabil. The pair currently split their time between making tooling and providing support for the rest of the plant.

Nabil takes the toolpaths Norm has created in SmartCAM and turns them into complete machining programs for each plate. For example, if a set of tooling has 12 cavities, he will write a sub-program to cut the profile of a single cavity. “It’s one profile, one layer,” Nabil says. “I make that layer three or four times depending on the thickness of the part, then I pick up that sub-program and give it another work offset to cut each of the remaining cavities. All of the pockets are measured from the center of the fixture,” he explains. “We specify an X, Y coordinate for each of the pockets and run the same sub-program at each location.” In essence, the machine just cuts the same profile over and over at different depths and locations.

Before the expensive tool steel goes into the machine, however, a single cavity and matching punch are cut out of aluminum and checked against the print. “We always take the trouble to make an aluminum mock-up of the punch and the cavity plate,” says Norm, “just to make sure we haven’t made any programming errors.” Once dimensions are verified, they switch to steel.

Each tooling plate starts life as an 18- by 16-inch piece of hardened tool steel that has been squared and ground flat by the supplier (the added expense is well worth the reduction in machining time). Plate thickness varies from about 5/8 inch to 2 inches, depending on the size of the brake pads being made, and whether it’s a base plate or cavity plate. All of the external features and common locating holes in each plate are machined using canned cycles, and then the features specific to each plate, such as cavity profiles, are machined.

	OE Quality Friction currently runs two shifts per day on the production side and a single shift in tooling. The company's 14,000-square-foot building is now filled and they’ve added a third cure press to keep up with demand.

The punches start out as pieces of tool steel 20 inches long by the width of the punch. “It’s like a rack of ribs,” Norm says. “We do all the drilling and reaming in that strip while it’s still in one piece. Then we chop it up into sections that go straight onto a fixture. That way we don’t spend time unnecessarily facing and squaring pieces of steel. As long as we’ve got one ground flat surface that’s drilled and reamed for dowel pins, it just drops onto the fixture.” Each punch takes about 45 minutes to cut, and comes off the machine as a finished part. “We do a slight bit of deburring,” Norm notes, “and it’s finished – no hand work at all.”

Once completed, the tooling moves to the production side of the plant to begin the manufacturing process. There, each cavity is filled with a loose mixture of friction modifiers, lubricants, dry phenolic resin and catalysts. Once filled, the tooling goes into a 400-ton cure press. “It gets squeezed between heated platens at about 350 degrees Fahrenheit,” Norm explains. “During that period, the resin melts and flows around the other ingredients, then the catalyst works and everything hardens to form the finished friction material.

“These are five-daylight cure presses, so we’re cooking four part numbers at a time, and the fifth daylight is used as a heat-up daylight for the next set of tooling. Because all of our tooling is common,” Norm adds, “when the tools are closed, you can’t tell one from another. It could be running a three-cavity truck part, and underneath it would be a 20-cavity rear brake for a Beretta. The tooling is constantly going in and out of the press, and every six minutes or so, you get a set of parts.”

Once molded, the brake pads are ground to a uniform thickness, painted, assembled with any additional hardware required and boxed for shipping.

OE currently runs two shifts per day on the production side and a single shift in tooling. Their 14,000-square-foot building is now filled, and they’ve added a third cure press to keep up with demand. According to Norm, Nabil and Dan have become so proficient at producing tooling on the Haas that the “machine now outpaces the organization. We could pump out a lot more tooling, and the machine could run more, but our infrastructure couldn’t handle it,” he says. “We’d have to double our people in the office!”

That’s an enviable position to be in for such a young company. And though age discrimination may be alive and well, in the case of Norm Abbott, it looks like this old dog is teaching the industry some new tricks. 

< Back | 1 | 2 | 3

Article and photographs courtesy of CNC Machining Magazine (Winter 2001) and Haas Automation, Inc.