Electrochemical Metal Removal

Electrochemical metal removal

Electrochemical machining, or ECM for short, is a generic term that covers a group of various electrochemical metal removal processes. They all remove material based on the anodic dissolution of the metal by electrolysis.

Electrochemical metal removal processes break down into:

     

  • Electrochemical machining (ECM)
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  • Electrochemical drilling (EC drilling)
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  • Pulsed electrochemical machining (PECM)
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Electrochemical metal removal offers many advantages

Electrochemical processes are highly cost-effective methods of removing material without building up residual stresses. They produce gentle transitions and smooth surfaces. Electrochemical metal removal processes are used to produce holes with a high length-to-diameter ratio (EC drilling) and to shape small to medium-sized three-dimensional blisk airfoils in nickel-base alloys (PECM).

PECM (pulsed electrochemical machining)

As is generally the case with electrochemical material removal processes, no finishing of the machined surface is required. The PECM method used is an in-house development. In Munich, MTU has commissioned new machines developed and set up by MTU’s experts. 

Here is how PECM basically works: Material is removed electrolytically – that is in an electrolyte under the action of electric current – in a controlled manner from a metallic workpiece. In the process, the material to be machined is the positive pole and the three-dimensional metallic forming tool is the negative pole. The electrolyte used is an aqueous sodium nitrate solution, which flows between the anode and the cathode. The liquid has three main functions: It carries the electric current between the tool and workpiece, it removes the dissolved material and the hydrogen formed in the process from the machining area, and it dissipates the heat produced. The advantages PECM affords over conventional machining: The tools do not actually touch the workpiece, so they do not suffer wear in the process. Moreover, the process allows an unprecedented level of precision to be achieved, not least thanks to the extremely narrow machining gaps of just a few micrometers.