Superhard automation

END USER: Diamond Innovations Inc., (800) 368-6507, www.diamondinnovations.com.
CHALLENGE: Simultaneously improve product quality and productivity when EDMing PCD and PCBN cutting tools and wear parts.
SOLUTION: An automation process that incorporates work cells.
SOLUTION PROVIDER: Methods Machine Tools Inc., (877) MMT-4CNC (668-4262), www.methodsmachine.com.

In keeping with its name, Diamond Innovations Inc. continuously seeks inventive manufacturing processes to make its PCD and PCBN products, which include more than 3,000 geometries for cutting tools. The Worthington, Ohio, company custom makes about 90 percent of its tools in quantities from one to more than 50,000. The typical order quantity is 200.

EDMing is effective for cutting PCBN and PCD, but Diamond Innovations sought full process automation to optimize the operation. “The quality of the product was not at the optimal level we sought for our demanding customer base,” said Steve Chadwick, operations manager for Diamond Innovations, noting dimensional tolerances can be as tight as ±0.02mm (±0.0008 “). “We determined that two variables in our EDM operation were producing inconsistent results: individual, unique tooling and operator error due to manual part loading.”

Chadwick’s team determined the company could improve product repeatability, accuracy and productivity by incorporating more complete process automation. The company challenged several EDM providers to eliminate the inconsistencies and provide an automated solution that would increase flexibility and capacity without increasing labor costs.

To ensure the company was using the “best” equipment, Diamond Innovations sent the EDM suppliers a test-cut package that included several different grades and shapes of PCD. After inspecting the cut PCD and tabulating the results, Diamond Innovations determined the FANUC RoboCut wire EDM from established partner Methods Machine Tools Inc., Sudbury, Mass., had the fastest cutting speed and produced the highest quality tools.

Effectively automating that equipment, however, was more challenging than obtaining it. Short EDM runs of dissimilar parts are traditionally not considered conducive to full automation. Diamond Innovations cuts tools from master blank discs that range from 0.8mm to 5mm (0.031 ” to 0.197 “) in thickness and 50mm to 70mm (1.97 ” to 2.76 “) in diameter, with diamond particles varying from 1µm to 25µm (0.00004 ” to 0.0010 “). Each blank requires specific EDMing parameters for optimal quality. The PCD or PCBN is typically adhered to a thin tungsten-carbide backing for strength, and pieces are often exceedingly difficult to load, clamp and unload in a precise position.

To overcome the challenges, Methods and Diamond Innovations jointly developed a machine cell to address several variables. The first variable was designing an automated method to load and unload parts (cutting tools and wear parts) so the operator doesn’t have to. This was achieved by incorporating three FANUC RoboCut wire EDMs serviced by one FANUC M20iA robot in one cell. One side of the cell is an operator station, where drawers are located for introducing raw parts into the cell and a rack holds baskets for catching and removing the cut parts. “Now we can load blanks on Friday, leave for the weekend and come in on Monday to finished parts,” Chadwick said.

Another challenge was enabling a pneumatic clamping fixture in each EDM to accept the varying disc sizes and locate the robotically loaded tool. Generally, the blank is manually placed in a fixture, which is mounted on a pallet system that locates the blank precisely in an EDM. Because of the nature of using many different pallets, the fixtures must be manually clamped. Therefore, an operator is needed to manually clamp the disc onto the pallet. To automate the process, an automated clamping method was needed.

“We needed to find a way to grab the smallest edge of a disc in order to fully machine it,” said John Lucier, automation manager at Methods. “In EDM setups, these types of fixtures are uncommon.”

Courtesy of Methods Machine Tools