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  • Writer's pictureSara Hagmann

PECM Compatible Materials

Pulsed electrochemical machining can be used on a variety of materials. In this article, we'll explain which materials can be machined via PECM, and the resulting surface quality.

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Array of materials able to be shaped with electrochemical machining
L to R: Copper; Brass; Aluminum; Stainless Steel 440 C, 316, and 17-4; Pyrowear 53; Tool Steel A2; Steel 4340

For a material to be machinable by pulsed electrochemical machining (PECM), it must meet the following qualifications:

  • The bulk electrical resistivity must be <0.01 ohm*cm. Generally, this includes most metals and some semi-conductors.

  • If reinforcing particles are contained within the material, these particles must be <10 μm in diameter.

  • The materials must be electrochemically dissolvable. As a general rule, if the material can be electropolished, it can also be machined with PECM.

Voxel has experience with a wide range of materials and has evaluated these materials using standard processing conditions. Using this experience and assessment, Voxel has categorized the materials by ease of machining, with resulting surface roughness as a key metric.

chart showing approximate roughness possible for various materials when shaped with electrochemical machining.

Machinability. If a material is conductive, its ability to be machined by PECM is based upon the type of surface oxide formed upon application of oxidative current. Given the vast range of surface oxides that can form from minor changes in alloy composition, it is difficult to predict without testing how any new class of alloy will perform. If your alloy isn’t on our list, send us a sample and we will let you know how it performs!

Surface Finish. The material choice has an important effect on the surface finish. If the material is sufficiently conductive, contains no reinforcing particles, and is routinely electropolished, smooth finishes from PECM are generally easy to produce. However, certain materials that form weak, or disordered, oxide layers can generate rough surfaces (though rough for PECM is generally in the range of a typical surface finish produced from milling operations). In addition, all materials can have different surface finishes based on the electrolyte flow conditions required by the part geometry.

Exceptions. Certain materials under standard processing conditions may achieve higher accuracies and better surface finishes than other materials. Contact Voxel to discuss your specific material.

Hardness. Hardness is an irrelevant factor in PECM. The process is the same for many materials and has a consistent removal rate, so long as the chemistry and conductivity of the material is compatible; PECM can machine nickel superalloys at a similar rate to copper.

PECM is an excellent option for machining many different materials, and Voxel has worked with dozens of them. Even if the material you have in mind is not listed – or if you’re not sure what material would work best for your design – contact Voxel. We’re happy to discuss the performance of your desired material (and even test it, if needed!)

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