Plasma Electrolytic Polishing (PEP)

Plasma Electrolytic Polishing (PEP)

Post-Machining Surface Finishing

Plasma Electrolytic Polishing (PEP) is an environmentally friendly plasma-based electrochemical process to improve the surface finish of metallic components.   This process is performed by creating micro-discharges on the surface of component that are immersed in an electrolyte.  PEP has been performed on multiple alloys and provides extremely smooth surfaces with very low average roughness values in under 10 minutes.  The PE polished parts have Ra values lower than 0.03 microns.  This surface finish improvement process can be applied most alloys including steels, Aluminum, Titanium, Nickel and Magnesium alloys.  PEP treated metals exhibit higher corrosion resistance than the untreated starting material.


Detailed Process Description

In the PEP process, the untreated metallic work pieces are placed in an aqueous bath along with an electrode.  The electrolyte is environmentally friendly and unlike electropolishing, does not contain acids.  Application of high voltage to the part results in the generation plasma that envelops the surface.  The temperature of the electrolyte and the part is maintained below 90oC.  A minimal weight loss results during the treatment, caused by the leveling of microroughness and the removal of sharp edges.

Plasma Electrolytic Polishing (PEP)
  • Alloys processed: Steels, Aluminum, Nickel and Magnesium alloys and Copper.
  • Surface Finish achieved: Ra = 0.022 microns and Rz = 0.126 microns
  • Non-line-of-sight process
  • Green technology: no hazardous waste streams after electrochemical cathodic treatment

Any metallic component needing very high surface finish – typical applications include components for medical, aerospace, precision instruments and industrial manufacturing tools.

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