A new abrasive coating makes CBN tools sharper, more accurate, and longer lasting.
Dressing tools—used to reprofile, or grind, the shape of a worn cubic boron nitride (CBN) wheel back to its original form—are getting a much-needed facelift. Meister Abrasives USA has engineered a new kind of dressing cup abrasive coating that makes CBN wheels sharper and more accurate, and extends tool life.
CBN wheels are used to grind medical orthopedic components like bone drills and reamers. Accurate cuts and consistent shaping of the components are critical for medical device applications. However, the wheels inevitably wear down over time, requiring engineers to sharpen them with dressing tools covered in an abrasive coating that contains tiny diamonds.
Metal and vitrified bonding techniques have been the standard methods of creating the diamond coating and adhering it to the tools. Although both methods offer unique advantages, they each also have their drawbacks: poorly exposed diamonds in metal bonding can result in bond rubbing, which can dull tools, while porous vitrified bonds can succumb to brittleness and lose form in high-pressure grinding operations.
Meister’s hybrid diamond dressers, on the other hand, feature its hybrid bonding technology, which combines the best aspects of both bonding methods. “The sharper, more-consistent cut of the tools was actually our original goal,” says Bruce Northrup, general manager. “Better tool life was a bonus result of the development.”
Hybrid bonding technology combines the wear resistance of metal bonds with the porosity of vitrified bonds. The porous structure of the abrasive yields improved diamond exposure. The company engineered the abrasive at the molecular level so that the bond posts—the part of the abrasive coating that holds the diamond grains together—in the coating on the tool wear down at the same rate as the diamonds. This extends the life of the abrasive, prevents bond rubbing associated with metal bonding, and eliminates the need for frequent conditioning of the abrasive.
The company’s hybrid technology uses chemical and mechanical bonding techniques to elicit a natural porous structure between the diamond grains and bonding substance. “Imagine filling a glass jar with marbles,” Northrup says. “The spaces in between the marbles are ‘natural porosity.’ This is where you want the pores in a grinding tool, right next to each particle.”
Meister’s next step is applying hybrid bonding to grinding wheels. One medical application for such wheels will be grinding orthopedic components and tools that are manufactured with advanced ceramics.
Meister Abrasives USA, North Kingstown, RI