With pulsed electrochemical machining, it is possible to achieve high-repeatability production parts. This advanced process is a completely non-thermal and non-contact material removal process. It is capable of forming small features and high-quality surfaces.
Although its fundamentals remain the same as electromechanical machining or ECM, the variant, PECM or the pulsed electrochemical machining process is newer and more precise, using a pulsed power supply. Similar to other machining processes, like EDM and more, there is no contact between the tool and the workpiece. Material very close to the tool dissolves by an electrochemical process and the flowing electrolyte washes away the by-products. The remaining part takes on a shape like an inverse of the tool.
The PECM process has some key terms that it uses routinely. The first is the cathode—representing the tool in the process. Other names for the cathode are tool and electrode. Typically, its manufacturing is specific for each application and its design is the inverse of the shape the process wants to achieve.
The second is the anode—it refers to the workpiece or the material that the process works on. Therefore, the anode can assume many forms. This can include a cast piece of near net shape, wrought stock, an additively manufactured or 3D printed part, a part conventionally machined, and so on.
The third key item is the electrolyte—referring to the working fluid in the PECM process that flows between the cathode and the anode. Commonly a salt-based solution, the electrolyte serves two purposes. It allows electrical current to flow between the cathode and anode. It also flushes away the by-products of the electrochemical process such as hydroxides of the metals dissolved by the process.
The final key item is the gap—this is also the IEG or inter-electrode gap and is the space between the anode and the cathode. This space is an important part of the process, and it is necessary to maintain this gap during the machining process as the gap is a major contributor to the performance of the entire process. The PECM process allows gap sizes as small as 0.0004” to 0.004” (10 µm to 100 µm). This is the primary reason for PECM’s capability to resolve minuscule features in the final workpiece.
Compared to other manufacturing processes, pulsed electrochemical machining has some important advantages:
The pulsed electrochemical machining process of metal removal is unaffected by the hardness of the material it is removing. Moreover, the hardness also does not affect the speed of the process.
Being a non-thermal and non-contact process, PECM does not change the properties of the material on which it is working.
As it is a metal removal process using electrochemical means, it does not leave any burrs behind. In fact, many deburring processes use this method as a zero-risk method of machining to avoid burrs.
It is possible to achieve highly polished surfaces with the PECM process. For instance, surfaces of 0.2-8 µin Ra (0.005-0.2 µm Ra) are very common in a variety of materials.
Because of non-contact, there is no wear and tear in the cathode, and it has practically near-infinite tool life.
PECM can form an entire surface of a part at a time. The tool room can easily parallel it to manufacture multiple parts in a single operation.
