Case Studies

Graphite Case Study #1

A plastic injection molding company serving the electronics and medical device industries had difficulties making a mold for a component with a complicated contoured parting line. The double cavity mold involved four parting line burns, two for the cavity and two for the core. Each area required four electrodes.

The large electrode size required machining graphite blocks of EDM 200 material measuring 9” x 9” x 14”. Using carbide ball end mills at 40 in/min required a 13-hour tool path. Cutters wore out before the end of the cut necessitating three tool passes with a new cutter installed for each pass for a total cut time of 39 hours. The required accuracy of +/-.001” was never fully achieved.

Changing the tool to a 3/8” Dapra-style milling style DIAbide coated insert, and cutting at the same speed, each electrode was machined complete in one pass with no tool changes, saving 26 hours of machine time per electrode. In total, 416 machine hours were saved while completing the mold order. Additionally, the required tolerance of +/-.001” was effectively maintained.

Graphite Case Study #2

A leading supplier of molded plastics products for the microelectronics industry utilizes DIAbide coated end mills to machine sinker EDM electrodes used for making injection molds. The electrodes are made from various grades of graphite which include EDM 200, Poco 2, and Poco 3.

The supplier previously used uncoated carbide end mills at spindle speeds from 12,000-14,000 rpm and feed rates between 120-160 ipm. Tool life averaged 4 hours per tool. With DIAbide coated 4-flute ball and square end mills in diameters from 1/8” to 3/8”, and operating with the same cutting parameters, the tool life jumped to 60 hours. An improvement of 15 times over carbide tools. This allows for long-term unattended machining, yielding savings in machining and labor costs.

In addition to increasing productivity, the slower wear rate of the DIAbide coated tools provided a platform for improved machining accuracy and consistency while maintaining tight tolerances of +/-.0005” which are routinely required in the electrode industry. Again, this offers a savings by reducing the amount of adjustments required by the machine operator.