Incremental Sheet Forming with a CNC Machine

If you want to form a piece of sheet metal into a shape, you’ll probably think about using a die. That’s certainly a great way to do it, but it presupposes you can create or purchase the die, which may be a showstopper for small projects. [Dardy-7] has worked out how to use a lesser-used technique — incremental sheet forming — to get similar results with a CNC machine. The idea is to trace out the form on the sheet metal with a round blunt tool.

He got good results using an inexpensive dapping tool, although he’s seen other use heated titanium ball bearings. In addition, he’s worked out how to adapt existing tool paths, like the ones you might download from the Internet, to use with this technique. You can see a video of the workflow below.

The technique requires a jig to hold the workpiece that allows the tool to push the metal down. In the examples, the jigs are just quick plywood assemblies and the workpiece is 0.6 mm aluminum. Some of the jigs have support underneath to help create parts that have parts poking up (that is, a positive curvature).

We couldn’t help but think that a 3D printer could easily create a backing plate that would serve the same purpose as under support in the current jigs. [Dardy-7] notes the process is slow and not as accurate as some other methods. On the other hand, if you have a CNC machine it should be an easy addition to your repertoire.

If this makes you want to run out and buy a CNC machine, you might like to read this first. If you want to dive into the tool paths, we can help you there, too.

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