Molding Robot Parts from 2-Part Polyurethane Plastic

Last modified: February 24, 2024

Keeping up with the latest from Kenneth Maxon and his exciting robot endeavors is always a delight. His CNC workshop is well stocked, and he does sophisticated, exquisitely detailed work. Check out this photographic record of his most recent project he shared for all to appreciate:

Close-up photograph of metal parts with screws and bolts on a black leather surface.

Here's a view of the mold which is in 4 parts.  It's capable of making parts in 2 different configurations...

Machining tools and metal fabrication equipment on a table.

Mold parts clamped together and ready for the 2-part polyurethane treatment...

Metal fabrication and machining tools in a workshop.

The 2-part plastic is not poured, it is injected.   Kenneth says:

I'm often  asked how one gets the material to ‘pour' with such a high surface area to  cross section aspect ratio.  The trick comes in using a large bore syrenge to  push the material through the tool.  This also helps to cary some of  the smaller air  bubbles through and out by letting excess material overflow from the air relief.

Black plastic ISRE parts on blue background.

Here's what the parts look like after the plastic has cured, first configuration...

Maxon NORP 24V brushless motor with CNC, metal fabrication, and metrology applications.

And here's the second configuration.  Kenneth writes:

After the first part comes out it is pretty easy to get a nice surface finish on all of the parts that follow.  The first part comes out a bit ratty as, no matter how well the  tool is cleaned, the  molding process pulls ‘magic'  chips out of it.  Additionally, the 2-part materials and  the mold release wax have a small chemical inter-action with the soap  film left when  washing the tool.  Once the first part is pulled from the  tool, all of the following parts come out with a great surface finish like those shown in the photo.

Motorized wheel hub component with labeled parts.

This photo shows the molded parts installed on Kenneth's robots.,.

Details on how these molds were machined can be had on Kenneth site.

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