Above: Removing burrs by wiping the face of metal with a brush using specific paths, feeds, speed and penetration can save companies time and cost.

As alloys advance, so too must methods to deburr materials

July/August 2014 - Auto sales are on the rise, and with that comes demand for additional fabricated components. Valiant Machine & Tool Inc. makes parts for 500,000 engine blocks each year—that requires a much faster pace of metal processing than say, supplying the global aerospace industry, which makes a fraction of that per year.

“I might have 45 seconds to deburr components for a car engine but three times that amount of time for an aerospace part,” says Greg Elder, engineer at Valiant, based in Windsor, Ontario. 

The company makes equipment to handle assembly, weld or modify customer parts. “We also have deburred engine blocks, heads, transmissions cases, valve bodies and several dozen aircraft parts,” Elder explains.

Whether cutting down on weight by switching to aluminum from steel or using advanced lighter weight alloys, manufacturers are steadily adjusting to the latest technological advances and emission reduction standards. When it comes to cutting metal, burr conditions change as materials change. 

“Customers are using harder aluminum and it throws off the kind of burr produced and they’re not used to it,” Elder says. “The fastest and simplest way to remove the burr is wiping the face with a brush using specific paths, feeds, speed and penetration, and not having to use more complicated, costly methods.”

Valiant uses brushes made by Osborn International in Brooklyn Heights, Ohio. Michael Akuszewski, field application engineer at Osborn, helped Valiant design a spindle to use during the deburring process. “We showed Valiant how to compensate for brush wear, [and] recommended tool paths, brush penetration [rates] and brush speed,” Akuszewski says. “We developed a burr class chart at Osborn and used it to help Valiant determine what size burr would be seen on the part that Valiant was processing.”

Not one size fits all

As brushes wear down, it’s hard to detect and compensate for the bristle wear. Valiant recently worked with a customer that dictated a method for brush wear compensation. “We ran into a problem because initially we didn’t understand how the brushes worked,” Elder says. “Mike [Akuszewski] explained how different styles and brush materials work; whether it cuts on the bristle end or edge, for example. We then approached our customer to explain why their initial idea of wear compensation seemed to make sense, but in reality wouldn’t work in this case. While it’s not high technology understanding how a brush works—side action or tip action—our original methodology didn’t approach the problem correctly.

“The customer concept was to detect the bristle tip pressure,” Elder continues. “We needed to monitor bristle penetration, which is the amount the bristle would penetrate the part if it stayed straight instead of bending. Osborn gave us sample brushes to test to get our methods down right—which was crucial because working in the automotive industry, every job is completely different, and with different feeds, speeds and brush types, testing is critical.”

Each cutting application results in a different type of burr, some more extreme than others. “We were looking to remove class one or two burrs, smaller classes of burrs,” Elder says. “Mike explained to us that classes are developed by machining, creating different kinds of burrs, and he actually came to our shop and looked at our particular part and application to make sure we had the right brush selection and technique.”

Deburring an edge can sometimes smooth the adjacent surface too much, creating a new problem, as Valiant found during a testing for a particular job. “The brush passes the edge then the surface of the part. If the feeds, speeds or penetration are wrong, the surface could end up being too smooth, resulting, in this case, in possible gasket failure,” Elder says. “We actually improved the surface microfinish slightly and this led to the concern. So we sent the part away to Osborn for more testing and they came back with some alterations to brush selection and our feed and speed to correct the situation. The test parts were sent to the automaker and after everyone reviewed it, we were able to proceed.”

Keeping current

Osborn keeps tabs on industries its customers serve and makes adjustments accordingly. The company has proprietary formats and filaments in its brush and applies them to the appropriate application. When materials change, burr class changes and brush aggressiveness needs to be adjusted. “When you need more aggression, we have a large brush face with the highest density and the highest load for the largest of burrs, Akuszewski says. “And when you don’t need that, we have a lighter staple set or turbo option. We have different variations of product that other companies just don’t have.”

Using its own dies and machines, Osborn can adjust the format of the brushes. Each year the engineering team studies which formats need improvement. “We know how to apply different formats and materials,” Akuszewski says. “Anyone can make a brush, buy the abrasive filament and pour the polyurethane into a cup, but we have multiple formats that can fit applications. We combine that with field expertise that we can present to a customer.”

Customers can send sample parts they’re working on to the Osborn lab. Osborn then takes those parts and develops a deburring process by testing out different brushes, conducting deburring studies, followed by a written report it sends back to the customer so they can incorporate Osborn brushes into an automated deburring process.

Material usage evolves over time and Valiant engineers adapt using the newest technology and alloys. “Everything used to be cast iron or cast steel. Aluminum definitely has its issues,” Elder says. “Aluminum was softer at first but the newer alloys are introducing characteristics we haven’t worked with before. Our customers are concerned with the burr because it’s not coming off easily or it’s throwing off functionality [of the finished part].

“Sometimes you’re deburring so employees won’t cut themselves because of the burr or sharp edges that machining leaves,” Elder says. “Other times it’s for functionality, the burr may cut a seal or gasket or even score a mating part. Changes in materials are fluctuating more often than they used to.”

Osborn application engineers travel throughout North America to monitor industry innovations affecting their customers.  “We recently had a new group of engineers that needed to know a cycle time of deburring a complete engine block. At the time, we had CNC time open, so we loaded the block into the CNC machine, developed the tool paths and ran the block [through] to prove out our process,” Akuszewski says. “We then sent the block back to the end user with a report for evaluation and approval. The block is now in production and completely deburred in machine with Osborn products.” FFJ