A manufacturing process that quickly, precisely and cleanly machines surfaces of metals of almost any hardness sounds too good to be true. However, that’s exactly what Pulsed Electrochemical Machining (PECM) technology delivers.
Often described as “controlled corrosion,” PECM is based on the principles of electrolysis. Essentially, an electric current is passed through an electrolyte solution that flows in the gap between a cathode tool and a part, dissolving materials from the part into the solution as it is machined into the complimentary shape of the tool.
“I think the coolest thing about this process is the way that it can accurately and precisely remove metal without actually contacting the part. We’re talking a gap the size of a human hair or less between the tool and the part,” explains Michael Bromley, lead mechanical engineer at Voxel Innovations.
Based in Raleigh, North Carolina, Voxel is a leading innovator in PECM, which is unrivaled in its ability to quickly and accurately machine specialty metal alloys needed for making turbines, medical devices and surgical equipment. The company leverages the unique technology to deliver critical, high-value parts to aerospace, energy and healthcare customers.
Voxel Innovations CEO Daniel Harrington says PECM is far more common in Europe than the U.S. because of the difficulty and interdisciplinary nature of the process as well as it not being taught in U.S. universities. Noticing this gap, Voxel has designed, built and is currently operating its own proprietary PECM machines, offering customers the many benefits of this process for development projects, prototypes and small-scale production.
One of the biggest advantages of PECM is high repeatability even when machining features on a micro-scale. “By building the complexity into our cathode tool, we can form an entire 3D surface at one time,” says Bromley. “For instance, turbine blade surfaces feature complex geometry and we just build all that complexity into our tool."
“We’re very good at doing high-volume production because once the tool's designed, being a non-contact process, there is no wear on the tool so we can continue using it over and over again,” he adds.
Modern CAD Tools & Simultaneous Editing
To design its PECM machines, Voxel chose Onshape, a modern professional 3D CAD system that unites modeling tools and design data management in a secure cloud workspace.
Being cloud-based was one of the most appealing factors when evaluating Onshape against other CAD systems, as no additional or expensive hardware had to be purchased to run CAD. Bromley says that beyond the convenience of the cloud, which enables immediate access to their designs on any computer, phone or tablet, Onshape has fundamentally improved the way his team models.
He says he particularly appreciates the novel approach of Multipart Part Studios, where multiple parts are intuitively designed together in one workspace (instead of in separate files).
“Onshape definitely makes it easier to modify designs because a single sketch can drive multiple features and multiple parts,” Bromley says. “Previously, I would basically write some dimensions down on a piece of paper and model the separate parts and then assemble them. And then probably use some in-context-like editing to modify each part independently.”
“With Onshape, you can create a single sketch that's updating multiple parts at the same time without having to remember that if you change one part, you need to go change another part that's mating with it,” he adds.
The Voxel team also values the option for multiple people to simultaneously work on the same CAD model. With no risk of duplicate files, it’s always clear what the latest version is and who did what.
“In Onshape, whether we’re working in the same tab or in different tabs in the same assembly, I can always track the engineers’ changes and see what they're working on,” Bromley says. “All this automatically happens in the background, offering all the benefits of a PDM system without any of the physical effort you have to put into a conventional one.”
Responsive Technical Support
Overall, Bromley says he is most impressed with the responsiveness of Onshape’s technical support team, which he frequently contacts to propose ideas for improvements, discuss minor issues or ask questions about how to use a feature.
“With previous CAD systems I’ve used, I was essentially on my own. If it wasn't in the help manual, then I’d just go to the online forums and hope for the best. Help definitely wasn't readily accessible and it was difficult to get in contact with anyone at the company,” he recalls. “Whereas tech support is a built-in, integral part of Onshape."
“It's also easy to quickly get answers using the Feedback tool, which lets you mark up screenshots, and if you’re willing to share your Document with tech support, they can work with you even faster to see what’s wrong. This just would have been impossible with my previous CAD system.”
Rethinking American Manufacturing
As PECM remains a vastly underused process in the United States, Bromley notes that Voxel’s future challenges include educating the marketplace as much as advancing the technology.
“Educating design and manufacturing engineers is a critical part of what we do and we are spending more time working at the earliest phases of projects to help engineers design for manufacture to take advantage of PECM’s unique benefits,” he says.
“It’s exciting to help our customers deliver new, higher-performing designs that were not previously achievable through conventional machining methods.”