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Electropolishing Services

Purpose: Metal removal, remove stress risers, corner rounding, edge sharpening, deburring, providing high luster, removing heat effected zones and micro-cracks, and often improves the products fatigue life.

Process: The NNI EP process utilizes various engineered blends of acids that are designed to dissolve the components of the part’s material, when the part is connected to a positive electrical charge, placed in a bath of engineered acids, in the presence of a negatively charged counterpart, miracles can happen. The part then becomes the anode, the counterpart becomes the cathode. Ions flow from the part to the cathode, in a somewhat disproportionate manner. The irregularities such as corners, burrs, and protrusions become high current density areas, these polish the fastest. Low areas or middle areas polish slower. ID’s will only polish if there is exposure to a cathode.

During polishing, the acids become saturated with the dissolved metals and metal salts from the parts that have been polished. During repeated use, the solution approaches its equilibrium point and then begins precipitating out additional metals and salts to the bottom of the EP system as sludge. The majority of the metal in the solution plates to the cathode.

 

Considerations:

  • Oxygen is liberated at the anode, and hydrogen is liberated at the cathode. Therefore, EP will not cause hydrogen embrittlement of the parts.
  • EP can improve fatigue life by removing cold working stresses, or heat effected zones on the cut surfaces, smoothing stress risers, removing micro-cracks, and rounding corners.
  • NNI can also modify the EP effect to sharpen edges and points.
  • The EP effect when done properly, can improve a finish typically 2 fold, or more if tolerances allow. i.e., a 8Ra will be reduced to a 4Ra.
  • Proper EP can greatly reduce the possibility of bacterial growth on critical surfaces.
  • An area to attach the rack should be identified prior to RFQ.
  • Typically, part designers target .0008” to .0010” inch removal per surface, if maximum fatigue life of the product is a concern.
  • Parts typically need to be back figured by NNI engineering to allow for the material that the customer’s design requirement needs to be removed.
 
  Micromachining Facility / Headquarters
5507 Avion Park Drive, Highland Heights, Ohio 44143
Tel: 800.474.4322 Tel: 216.761.5387 Fax: 216.761.0455
email:
sales@normannoble.net
  Micromachining Facility / Plant #2
5340 Avion Park Drive, Highland Heights, Ohio 44143

Micromachining Facility / Collamer
1650 Collamer Road, Cleveland, Ohio 44110

Copyright © 2008 Norman Noble, Inc.