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PECM
Cross-section of internal“ serpentine” shaped features machined via OPECM in-situ cathode methdology on additive components. OPECM can machine non-line-of-sight features like these to sub-um tolerances.
Pulsed electrochemical machining( PECM) removes material through controlled anodic dissolution rather than mechanical cutting or thermal ablation. As a brief technology summary: instead of relying on physical tool contact, the inverse geometry of a cathode tool is electrochemically“ copied” into a conductive workpiece while an electrolyte flows through the small gap between the two electrodes. Because the process is non-contact and non-thermal, PECM is largely unaffected by material hardness or strength and can produce superfinished surfaces without recast layers or heat-affected zones. One of the characteristics that makes PECM attractive for complex internal parts for highvolume industries like semiconductors or aerospace manufacturing is its scalability. Once a cathode geometry and process parameters are established, the process exhibits high stability and repeatability with minimal tool wear, allowing a single cathode to machine or finish many identical features in parallel. In practice, this means that dozens( or in some cases hundreds) of holes, channels, or microfeatures often found in showerheads or heat exchangers can be processed simultaneously using a customized cathode tool, enabling consistent feature quality across large production volumes while maintaining tight dimensional repeatability. Crucially, OPECM builds on this foundation to address geometries that fall outside the lineof-sight of conventional machining methods. OPECM incorporates oscillatory cathode motion and specialized voltage pulse routines that allow the electrochemical reaction to evenly address surfaces within confined or curved geometries. By combining controlled tool motion with precise electrolyte flushing, the process can localize
material removal on complex internal features while preserving surrounding geometry. In addition to oscillatory cathode motion and specialized voltage pulse routines, OPECM can utilize in-situ cathodes positioned directly inside enclosed geometries. These cathodes may be fabricated separately and inserted into the component, or in some cases additively manufactured within the part itself and later dissolved during processing. By establishing the required inter-electrode gap from within the geometry, OPECM allows the electrochemical reaction to occur inside fully enclosed channels or cavities where traditional tools cannot physically reach. Research on representative turbomachinery geometries has demonstrated how this approach can extend PECM finishing into enclosed regions that would otherwise be inaccessible. In experimental studies using additively manufactured nickel alloys, OPECM reduced internal surface roughness within serpentine channels from roughly 4 – 5 µ m Ra to approximately 0.24 – 0.45 µ m Ra while maintaining geometric fidelity along curved internal features. The results showed consistent material removal across internal surfaces even where no direct tool line-of-sight existed. To enable this type of internal finishing, several tooling strategies can be employed. In some cases, custom cathodes are positioned to influence electrolyte flow and electrical field distribution across enclosed surfaces. In others, sacrificial or in-situ manufactured cathodes can be incorporated within the component during additive manufacturing and later dissolved during the electrochemical process. These approaches allow OPECM to establish the controlled interelectrode gap required for machining even inside fully enclosed geometries, expanding the range of internal features that can be post-processed without splitting the component or introducing additional joining operations.
About the author
Kirk Gino Abolafia is the technical marketing and sales manager for Voxel Innovations, an advanced manufacturer in North Carolina, USA, specializing in pulsed electrochemical machining( PECM) to produce high-value and high-volume parts for critical industries from aerospace turbine blades to nitinol medical devices. Kirk has written extensive technical content on PECM for publications ranging from aerospace, medical, robotics, STEM, additive manufacturing, and more.
22 Heat Exchanger World May 2026 www. heat-exchanger-world. com