Electroforming and Electrical Discharge Machining (EDM) both earn the renowned title of ‘high precision metal part manufacturing process’. What are EDM and electroforming exactly? How do their processes correspond and their outcomes differ? And… why should you care?
Both EDM and Electroforming use electrolytic baths
The most important part of the process in both EDM and electroforming takes place in electrolytic baths. In this electrolytic bath, a positive and a negative electrode are placed. The bath contains a solution of metallic salts and a power source of direct current (DC). Depending on which process is used, the voltage can attract atoms from one metal to the future end product (additive), or pull the atoms away from it (subtractive).
Electrical Discharge Machining is a subtractive process, whilst electroforming is an additive manufacturing process. Both result in very high precision metal parts. But the differences in the process - and thus the end results - are significant:
Electroforming: photolithography
Before the electroforming process is conducted in the electrolytic bath, a photo sensitive coating is applied on a conductive surface. Only the areas that have been exposed to ultraviolet light through a mask will be targeted by the material in the electrolytic bath. Atoms from the cathode then pass through the bath and bond with the metal. The photolithography process determines the extreme precision of electroforming.
Because EDM is subtractive, it can’t use photolithography. This means tolerances of minimum variances are much higher with EDM than that with electroforming. Electroforming reaches tolerances of only 2 micron, while tolerances for Electrical Discharge Machining reach 50 microns.
Electrical Discharge Machining: sparking
EDM disconnects material in small bits by electrical discharging (sparking). The electrolyte in the bath is non-conductive, so a high enough voltage will break down the dielectric and cause a spark. Material is therefore subtracted by a series of rapidly recurring current discharges. Unfortunately, the sparking can cause the end product to contain burrs that need to be polished after the process.
Why you should care
Even though both Electrical Discharge Machining and Electroforming both leverage electrolytic baths, they are two different processes with very different outcomes. This means that your technology of choice can have a significant impact on quality of your final product. Good luck with finding the technology that enables your next innovation!
To learn more about the Electroforming technology, download the Whitapaper Electroforming here.
