I learned my lesson on quality sinker EDM supplies years ago I worked for a high quality injection mold making shop. CNC EDM’s were just becoming standard practice and the owner invested in a brand new Sodick CNC EDM.
Unfortunately, he neglected to invest in good tooling and we were left with the old V-blocks, angle plates and fixtures from the antique manual EDM in the same room. He had managed to be penny wise and pound foolish to a high degree.
Investing in a completely integrated EDM machine tooling package for sinker EDM or wire EDM is as essential as using the correct steel for your injection mold components or carbide cutter in the CNC mill.
A very short history of EDM tooling
For the general public EDM is still a relatively unknown metalworking process. Unless one has had personal experience or knows someone who works in the field, chances are good that the world of electrical discharge machining is a mystery.
Like any specialized industry, EDM has it’s own terminology and way of doing things. The slang that is used could easily mislead a bystander into thinking something quite different is going on than is actually the case.
Words like tweak, bump, tickle, feather, smack, toast, NFG, fudge, hide and zit are all used on a daily basis. Actually, zit is less common now than in the past, due to improved circuitry and techniques. A zit is a DC arc, or pit that is EDM’d into the steel by mistake.
With the ever-improving technologies available today, EDM has moved away from being somewhat of a black art and into a fully explainable and manageable metalworking process. No longer is it a machine of last resort or specialty, but a mainstay of the industry.
Robots, electrode changers and pallets for sinker EDM
At one time, not so long ago, graphite electrodes were set up manually, requiring continual operator attention. There were no standardized holders and most people used angle blocks, vises or Vee-blocks to set up and hold electrodes. This actually works well, but is also very time-consuming and demands a high level of skill.
Next came the standardized electrode holders, such as System 3R. This changed everything almost overnight. Now electrodes could be moved from the milling machine, lathe or grinder and installed in the sinker EDM with no set up time.
Improvements were made on the holders and the repeatability and reliability increased dramatically. Pneumatic chucks made the process simpler and more accurate. The clamping pressures are more consistent now, thus ensuring repeatability day in and day out.
Competition for industrial supplies such as sinker EDM supplies has resulted in high quality tooling, graphite, EDM copper, tubing for hole making, EDM dielectric oil, threading electrodes and much more.
Tool changers were built into the sinker EDM to enable overnight machining and less operator involvement. Operators could load the tool changer up with dozens of electrodes, program the machine to burn all night and over the weekend, which set the process into a production mode.
Now there are robots that select workpieces mounted on pallets and change electrodes, leaving the guesswork entirely out of the equation. These sophisticated tools require a high degree of organization, but once set up they can run almost indefinitely. Some tool magazines can hold 100’s of electrodes and many pallets with mounted workpieces.
These robots can move from the electrode machining center to CMM to sinker EDM, all without human intervention. At least that is the theory; in practice it is not that easily accomplished, though it certainly can be done.