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Week - 09 Molding and Casting

2018-03-23 Kenny

Assignment

  • group assignment: review the safety data sheets for each of your molding and casting materials, then make and compare tests with each of them individual assignment: design a 3D mold around the stock and tooling that you’ll be using, machine it, and use it to cast parts

Acknoledgements

  • Originally I wanted to use Solidworks because they provided us with a interface to othermill, which we use here. But since I had a fellow student how was already conversant in these technologies with Fusion 360 and due to the tight time constraints, I decided to try out Fusion 360.
  • My idea is to keep the mold simple as possible. I saw how my fellow student tried to make two parted mold with burling but it snapped off and furthermore the machining time will be quite long.
  • So I decided to make a mold for a simple coin. To make a negative silicone mold, one have to mill the stock from the top and the model has to be positive.

Design

  • After installing, with “File” > “New Design” you can create a new design. I found it quite useful that everytime you save, it creates a new version in a version control software
  • Fusion supports sketches as well as primitive solids cast
  • I was alway found of the circular letters on coins. With Inkscape it was possible to align text to a path which was a circle. cast
  • It was possible to import the svg file and extrude it, but many detail was lost and Fusion crashed several times so I gave it up. cast

Setup

  • After swiftly designing the coin by extrude-cutting the center groove and simple text, you open “MODEL” > “CAM” to start preparing the model for cnc machining. cast
  • In the CAM view, first we have to create a new Setup by clicking on “Setup” > “New Setup” on the top toolbar to configure the stock. Here are some configuration I had. cast

cast

cast cast * For the rough cutting you need to select from the tool bar “3D” > “Adaptive Clearing” cast * Here are some configurations for the actuall milling and the the roughness/passes of the clearing. cast cast cast

  • We need to configure and specify the tools we will be using. cast cast cast

  • After configuring the tool we can see some preview passes: cast cast cast

  • For the fine cutting we select from “3D” > “Contour” and here are some parameters: cast

cast cast cast cast cast

  • To simulate the whole process, we need to specify the tool head of the mill to find out whether there are collisions with the stock. cast cast cast cast cast cast

  • After successfully simulating (no red signs) we can go to “Postprocess” to export g-code for the Mill. cast cast cast

Fabrication

  • Rough cutting cast
  • Fine cutting cast
  • To clear out all the remaining wax from the cracks, I used compressed air. cast
  • I could have milled the outside boundary to pour in the silicone, but it would have required bigger chung of wax and more time, so I taped some paper onto the wax with a rubber band. cast
  • But the silicone was already hardened because we did not use it for 3 years, so for a quick fix we used epoxy and silicone for seams, which unfortunately was not dry engough and was partly destroyed. cast cast cast cast cast

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