Cutting Tool Engineering

December 2011 / PCD Days

PCD progress presented at technical conference
The Vollmer of America Corp. recently held its PCD Days at its headquarters in Carnegie, Pa. This brief video report offers a glimpse at two of the machines on display during the technical conference: the QXD 200 rotary erosion and QWD760 wire-erosion units.

Vollmer demonstrated EDM machines engineered for forming, finishing, and resharpening of PCD cutting tools. EDM is a non-contact process; with solid-state circuitry controlling spark duration and frequency within nanoseconds, it can produce tool finishes within 0.2µm Ra and in many cases eliminate the need for finish grinding. Among the machines in action were the company’s QXD 200 rotary erosion and QWD760 wire erosion units; video is available at www.xxx.x In addition, Vollmer PCD product manager Arndt Hauger presented information regarding use of the QXD machine to polish PCD cutting edges.

More than 70 PCD tool manufacturers from the U.S. and Canada attended the three-day conference. The second day featured presentations by major manufacturers of PCD materials describing recent developments in PCD tooling technologies, including:

Innovative ways to mount PCD cutting edges

PCD can be directly sintered into contoured veins on a tool body, eliminating the need for a braze joint that can fail at high operating temperatures. Product line and business manager Matt Collier of MegaDiamond said the company’s V-Tec process creates tools that can run at one-and-a-half times the cutting speeds and more than ten times the feed rates of brazed PCD tools in demanding applications such as milling openings in carbon-fiber-reinforced-polymers used in aerospace manufacturing.

Layering and coating to prevent chipping

The combination of a matrix with reinforcing fibers in composite materials represents an interrupted cutting scenario that can chip PCD tools. Regional technical manager Stephen Kelly of Element 6 described the company’s new WPC 102 grade that features multiple layers engineered to protect the PCD and minimize chipping. The grade has a 350µm-thick base layer of multi-modal (both 2µm and 10µm size grains) PCD sintered to a tungsten carbide substrate, covered by a 20µm-thick “functionally graded” layer that blends from PCD to metal, and topped with a 30µm thick outer layer of metal (molybdenum). Introduced within the last six months for machining highly abrasive wood and particleboard products, the grade is being tested in other materials.

Fine grain to boost heat resistance

Many advanced workpiece materials are poor conductors of heat and can subject a cutting tool to damaging high temperatures. Application development specialist Dwight Dyer of Diamond Innovations, Inc., discussed the Compax 1200 PCD grade, whose 1.5µm grain size efficiently distributes heat and has shown to improve performance in tests in tough-to-machine materials such as titanium 6Al4V. The grade also boosts productivity in high-speed machining of certain aluminum alloys.

Tuning material content to specific applications

Sales manager Mike Mustin of American Superabrasives Corp. discussed PCBN materials, which represent a growing market opportunity for toolmakers. Mustin said that fine-tuning PCBN tools to specific applications depends greatly on the CBN/binder content of the grade as well as other considerations such as edge preparation and machine rigidity. Grain distribution is another issue, as new grades are being developed with more homogenous relationship of binder and CBN grain content, resulting in greater strength and reliability.

In addition to the PCD manufacturer presentations, Michigan State professor Viktor Astakhov PhD, FSME, outlined the multiple, interconnected factors that determine the success of PCD tool application. He stressed a systems approach to machining operations that incorporates all aspects of the cutting process.

In another presentation, Werner Lueken, product manager for tool measuring machines, Zoller Inc., described a growing demand for extremely precise tool measurement in response to pressure to manufacture products with increasingly greater ecological and energy efficiency. Lueken said Zoller provides solutions for measuring PCD tools and saw blades with accuracy down to 1µm (0.00004") in the diameter.

Scott Ries, Vollmer PCD division manager and conference organizer, said the company “places great value on our ability to not only provide machine solutions to the customers, but also provide material and application resources. The turnout at this event verifies in my mind that that is the approach valued by our customers.”

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