Automating the EDM Process Is Good for Business

Diamond Innovations has realized three overall benefits from its investment: increased consistency, higher quality, and gains in capacity.

Part consistency and repeatability are important outcomes in EDM manufacturing. Inconsistent results, possibly from operator error due to manual part loading, can be very costly. Automation can improve product repeatability and, at the same time, reduce labor and strengthen a manufacturer’s bottom line.

Today’s manufacturers may have high-mix, low-volume component needs. Although automation traditionally has been for high volumes alone, today’s automation cells allow for both one part or multiple parts to be run and allow unattended operation, opening up valuable resources and saving costs.

Manufacturers using EDM technology now can use a common interface/ fixture to accomplish single-part loading as opposed to using a different setup for each new part run. In a properly designed cell, high-mix, low-volume jobs can be set up and run using automation.

It also is suitable for moldmakers who are working with electrodes and molds.

An example cell for moldmaking might include a 5-axis milling machine for producing electrodes that is integrated with a die sinker EDM. With 5-axis technology all five sides of the graphite electrode can be machined without the need to pick it up to change its position. Less handling reduces the possibility of errors caused by manual manipulation.

Once the electrode is finished, a robot can pick it up and move it to a die sinker EDM for producing a mold. Because electrode cutting is a lengthy process, moldmakers often start a part and let it run partway through the night. With automation, a small number of electrodes can be cut throughout the entire night.

Sourcing Automation

Manufacturers using the EDM process have choices for sourcing machine tool automation.

One option is to conduct the installation in-house after purchasing a robot directly from its manufacturer. Because machine tool automation is extremely specialized, it is important to involve someone with expertise specific to this process.

A second option is working with a machine tool company that offers integration capabilities.

A third option is to hire an integrator who will install the robot’s electrical and mechanical systems. Integrators handle the interfacing of the robot to the machine and other ancillary equipment. They take care of designing, purchasing, and integrating grippers, the infeed/outfeed system, and the safety fence. Further, integrators can provide valuable training.

Shops should understand who has responsibility for the automation system so that their needs get properly addressed.

The application drives the best automation choice. Machine tool automation is available in different types and can include an articulating arm; a Cartesian 2-axis or 3-axis robot; a linear-rail robot; and hard automation including cylinders, actuators, and switches.

The considerations that need to be addressed include a method to grab the parts, a way to bring parts to and from the robot, and an interface to the machine tool.

EDM Automation: One Example

A collaboration between Methods Machine Tools and Diamond Innovations, Columbus, Ohio, led to the design of a machining “cell” concept for automating the loading/unloading of parts and optimizing cut quality. Because of varying and irregular part sizes, many of the parts were difficult to load, clamp, and unload with precision.

Diamond Innovations, a wholly owned subsidiary of Sandvik AB, is a manufacturer of superabrasive products used for material removal. It serves the electronic, aerospace, infrastructure construction, energy exploration, mining, and automotive industries.

It manufactures more than 3,000 polycrystalline diamond (PCD) and polycrystalline cubic boron nitride (PCBN) part geometries that are incorporated into cutting tools for the metalworking industry. Approximately 90 percent of these parts are custom-made in quantities from 1 to more than 50,000. A typical order quantity is 200.

EDM cutting technology is a key production method that has served the company well in its manufacturing process. While CNC EDM tools have been used for decades, full process automation was not applied.

“The quality of the product was not at the optimal level we sought for our demanding customer base,” said Steve Chadwick, Diamond Innovations operations manager. “We determined that two variables in our EDM operation were producing inconsistent results: individual, unique tooling and operator error due to manual part loading.”

The company needed to eliminate these inconsistencies while remaining flexible without adding to labor costs.

Adding Automation.

Fanuc Robo- Cut wire EDMs connected to a Fanuc M-20iA robot were installed to produce short runs of dissimilar parts.

On one side of the cell is the operator station where drawers are located for introducing raw parts into the cell and a rack holding baskets for catching and removing the cut PCD parts. The automatic loading system eliminated the need to have an operator standing by to load and unload the parts.

“Now we can load blanks on Friday, leave for the weekend, and come in on Monday to finished parts,” said Chadwick.

This meant important productivity gains were achieved.

Within the automated system, a robot-mounted laser displacement sensor measures the flatness of the blanks as they are held in the fixture. After the blank is loaded into the EDM machine, the robot positions the laser over the part and takes several measurements to ensure the disk is located within tolerance. If the disk is not within these parameters, the robot repeats the procedure at precise, calculated adjustments until an acceptable result is achieved.

Diamond Innovations has realized three overall benefits from its investment: increased consistency, higher quality, and gains in capacity. The scrap rate from cutting errors also is now negligible, due largely to the automated fixturing and inspection processes.

www.methodsmachine.com