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This is a short video clip of the machining that is being performed on the part and fixture shown in the pictures below.

There are more pictures of the actual parts and fixtures in the CNC towards the bottom of this page.

1/27/2015 10:30:26 AM

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Molded ABS credit card slot for product

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Part has nominal wall thicknesses of about 0.090” thick with 2 to 3 degrees draft.

There are approximately 600 pieces to machine so finding a fast and easy way to fixture these parts is desireable.

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The section highlighted in green is what need to be machined.

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This is a CAD rendering of 2 parts on the fixture.

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 Here are the 2 actual parts installed on a 3d printed version of the fixture.

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1/27/2015 9:55:36 AM

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 CAD rendering of the fixture itself

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CAD rendering of the fixture and parts. Green area denotes area to be machined.

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This fixture was created by assembling the part to a block then subtracting the area where the part was intersecting the block. After some cleanup and filleting this is the resulting fixture.

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Here you can see a part that was macined using the fixxture.

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1/27/2015 9:55:40 AM

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Un machined part on the fixture

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1/27/2015 9:55:10 AM

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After the first fixtures were printed I determined that I would have to do some machining on the fixtures due to inaccuracies in the SLS printing process.

I added about 0.010” of material around the snap feature on the fixture block then machine it to size after setup in 3 fixture locations (g54, 55, 56) in the CNC. This assures near perfect placement in the cnc and a tight “SNAP” fit of the part on the fixture.

The part snaps so tightly to the fixture that it is somewhat difficult to remove and requires a tool to flex the plastic up and off the locating feature.

The first fixture blocks were printed using the FDM 3d printer and they were significantly more accurate and worked right out of the printer. The problem was that I didn’t feel that the abs m30 material of the FDM would stand up to the repeated installation and removal of the parts on the fixture. The Nylon 12 material of the SLS printer is much tougher and stands up better to this kind of abuse.

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1/27/2015 9:53:53 AM

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This is a good shot of the locating feature on the fixture. This area get machined after setup in the vise on the cnc to assure proper location and fit so the parts “SNAP” into location.

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1/27/2015 9:54:21 AM

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OOOPs should have deleted this image!

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1/27/2015 9:54:26 AM

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Here you can see 3 fixture blocks setup in 3 work coordinates on the machining center.

Once setup the fixtures first get the locating feature machined before machining the parts.

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1/27/2015 10:18:10 AM

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Fixture 1 (g54) after cleanup pass

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1/27/2015 10:18:15 AM

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Here you can see the cleanup pass around the locating feature as well as the actual cut machined into the part.

I label each fixture so if they need to be used again in the future I can get each one back into its original location.

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1/27/2015 10:18:39 AM

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Here you can see that I get a nice clean cut using a 2 flute 1/8” carbide end mill. So far I have not had to perform any de burring of the parts after machining.

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1/27/2015 10:20:35 AM

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The parts come packed 120 into a box and each part is individually bagged which slows down the modification process as they have to be re bagged after machinng.

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1/27/2015 10:20:53 AM