EDM Drilling

EDM Drilling

Reducing Risks

Our Electro-Disintegration Machine (EDM) drill was developed through a joint venture between GE and the Shuzhou Electro machining Research Institute in China. The primary application for EDM is the removal of finger dovetail pins on large steam turbines. Finger dovetail pins frequently become lodged or "stuck" in the pinholes due to corrosion and/or slight bending from centrifugal force.

Using a brass electrode and tap water as a coolant and cutting fluid, the EDM will relieve a lodged pin at the rate of 3 minutes/inch of drill depth. The old method of drilling would take up to an hour or more to remove a single pin, depending on the hardness of the material. Impervious to hardened material, the EDM uses ordinary tap water as coolant/flushing fluid, creates a non-hazardous waste, and reduces risk, as hazardous materials do not need to be shipped.

Computer control monitors the arc and all cutting to ensure consistency and rapid material removal. The 5-axis positioning capabilities of the machine ensure we follow the axis of the pin and do not penetrate the wheel material. Tests performed under shop conditions have allowed us to drill pins following the centerline within 2 minutes of arc.

The EDM can be used for the following applications:
  • Dovetail finger pin removal
  • Cross key pin removal
  • Balance hole drilling
  • Removal of steam strainer rivets

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