Driven to finish: People & Companies

With the many complicated components in an automotive system, one tiny burr, misplaced fit, chip, ding or uneven finish can wreak havoc and affect the performance of the entire engine. The industry looks for perfection down to the micromillimeter, and that’s where technology for finishing comes in. Products exist to tackle various aspects of automotive finishing, including Norton Finium, Orbitool and DeBurr-Z.

Knock Down the Peaks

When it comes to surface condition, smoothness really matters. Ra, or the arithmetic average of surface heights measured across a surface, gives a snapshot of the microscopic peaks and valleys on any given part.

“When you’re talking about bearing surfaces on a crankshaft or camshaft, even at a fine Ra there is wear on the shaft and bearings,” said David Goetz, senior application engineer at Norton | Saint-Gobain Abrasives in Worcester, Massachusetts. “Although it may be slight, all that metal ends up in the engine.”

Norton Finium microfinishing films use a proprietary resin system to hold grains in place for finishing in automotive engine applications. The film-backed ultrafine grit abrasives come in a range of shapes, sizes and grits to fit a wide variety of requirements and eliminate the concern of grain fallout, which could leave coarse scratches and result in defective parts.

DeBurr-Z follows the outer contours of the component with an adjustable force accommodating the type of material and the desired edge break. Image courtesy of Tapmatic

Used to finish the surface of many automotive components — including camshaft lobes and journals; crankshaft mains, pins, thrust walls and oil seals; and transmission shafts — Norton Finium is wound onto a roll that varies in length depending on the machine being used. The width of the film depends on the part being polished. A user places the film over polishing shoes attached to polishing arms while the part is secured in a fixture and the polishing arms are clamped around the part. The array keeps contact with the part and Norton Finium for a given amount of time, generating the desired finish.

“Polishing is a rubbing or abrasion process where the cutting fluid (mineral seal oil or polishing oil), the Finium abrasive and resin from the bond form a flurry, and that’s what’s doing the finishing,” Goetz said. “Typically, we’re only taking off between 3 and 5 μm when we’re lapping. By polishing, you get a better surface condition and the engine runs more true. In turn, it cuts down on the vibration and noise and adds to the life of the product.”

Smooth the Burrs

In the past, deburring was treated as an afterthought in the automotive industry. The focus always had been on more efficiently making parts and vehicles, but nowadays manufacturers review costs and work hours for all aspects of production. And manual deburring is time-intensive and subject to human error.

“We’ve realized that many shops weren’t factoring in the cost of someone in the deburring department manually damaging or scraping the parts,” said Stan Kroll, partner and general manager of J.W. Done Corp. in Hayward, California. “There were cases where thousands of engine blocks weren’t deburred properly and now they have to go back to fix them. That gets costly very quick.”

From the standpoint of quality, automakers can track engine failures to the tiniest burr in a camshaft. With possibly thousands of complex parts, an engine can be affected by one particular cross-hole shaving that enters a timing system and can cause the entire engine to fail.

Orbitool’s flexible shaft allows a user to bend and pre-load the tool. Image courtesy of J.W. Done

“Improving those cross-holes gets us one step closer to increased reliability,” Kroll said. “Higher-quality reliable parts made economically and quickly is the goal.”