Exercise 09: Molding and Casting


Molding & Casting


My Process (Molding & Casting)

:: March 23, 2018 ::

Molding

This week’s assignment was to design a 3D mold, machine it and use it to cast parts. I decided to return back to my Hex Blocks since this week’s assignment perfectly fits that project. I needed to create many versions of my Hex Blocks since they are meant to fit together in some capacity and light up using a halftone pattern. 3D printing these parts would take weeks, so having a mold to cast the parts will be of great benefit.

Modeling Mold

To create the mold, I needed to design the positive of the piece and create a box surrounding it. I used Fusion 360 for this process. The main points to consider:

  • 3-5mm thickness of box boundary
  • Want sufficient distance between top of object and top of box for structural reasons
  • 5-10 degrees inclination to walls of box
  • Single Sided Mold: From one view, should be able to see all of the object
    • The casting process usually moves from:
  • Hard to Soft to Hard
  • Hard (countermold) to Soft

    • Modeling Hex Block counter-mold in Fusion 360 and using Loft command Hex Block counter-mold in Fusion 360 Hex Block counter-mold in Fusion 360

    Milling Mold

    The next part of the process was milling the mold. I created a .stl file of my Hax Block in Fusion to use for the machining process. For the milling, I used the ShopBot and VCarve software at my lab. In VCarve, I updated the “Job Setup” and “Material Setup.” I then updated the “Toolpaths,” using a 3D Roughing Toolpath and saved the toolpath as an .sbp file. After setting up the right parameters in VCarve, I went into the ShopBot software and set the “home” position and zeroed x, y and z axes. I imported the .sbp files from VCarve in preparation for cutting. I then began cutting.

    ShopBot at Dassault Systems Fab Lab ShopBot at Dassault Systems Fab Lab ShopBot at Dassault Systems Fab Lab Using VCarve to set up my milling job Setting Wax material to be milled on bed Using VCarve to set up my milling job Using VCarve to set up my milling job Using VCarve to set up my milling job Using VCarve to set up my milling job Using VCarve to set up my milling job Using VCarve to set up my milling job Using VCarve to set up my milling job Using VCarve to set up my milling job Using VCarve to set up my milling job Using VCarve to set up my milling job Using VCarve to set up my milling job Using VCarve to set up my milling job Using VCarve to set up my milling job Using VCarve to set up my milling job Adjusting bit Double sided tape on back of wax material Placing material on bed Adjusting bit Running ShopBot software and checking Hard Wood Cutting Data and Chip Load ShopBot software Zeroing x, y, and z Zeroing x, y, and z Zeroing x, y, and z Zeroing x, y, and z Zeroing x, y, and z Zeroing x, y, and z Zeroing x, y, and z Zeroing x, y, and z Zeroing x, y, and z Zeroing x, y, and z Loadinf .sbp file into ShopBot software Starting milling process Hitting start button Milling process has begun Milling process has begun

    Milling process in action

    Milling process in action Milling process in action Milling process in action Milling process in action

    Milling process in action

    Milling process in action Milling process in action Milling process in action Milling process in action Milling bit Milling complete Milling complete Vacuuming material Completed counter-mold Completed counter-mold

    Casting Part

    The next part was casting. I used OOMOO 25 (Tim-Cure Silicone Rubber) to cast the rubber mold to cast my final part, the Hex Block. The pot life was 15 minutes (meaning, I had 15 minutes to mix together parts A & B and pour into my mold). Cure time was 75 minutes. After casting the rubber mold, it was time to make the final Hex Blocks. For this, I used OOMOO Smooth-Cast 326 (Liquid Plastic). This was much easier to mix together due to its liquid consistency. The pot life was 7-9 minutes, while the cure time was 60 minutes. Given how long it would take to cast these plastic pieces, I decided to create two more rubber molds to quicken the process.

    My finals parts came out pretty well. I will need to sand them down, but they came out great, and I am planning to create at least 10-15 of these pieces as part of my final project.

    Using 16 fl oz cup to measure necessary material for mold Using 5 fl oz cups for Part A+B materials Using OOMOO 25 Silicone Rubber for creating the counter mold Pot Life (15 min) and Cure Time (75 min) for OOMOO 25 Approximate amount of water to fill counter mold Spraying Mold Release for easy removal of mold Approximate amount of water to fill counter mold Approximately 7 fl oz (205 ml) needed for hex mold Mold release directions Sprayed mold Sprayed mold Part A & Part B for Silicone Rubber Poured Part A & B into counter mold Poured Part A & B into counter mold Poured Part A & B into counter mold Poured Part A & B into counter mold Poured Part A & B into counter mold 75 minutes later...releasing silicine rubber mold 75 minutes later...releasing silicine rubber mold Releasing silicine rubber mold Releasing silicine rubber mold Releasing silicine rubber mold Releasing silicine rubber mold Releasing silicine rubber mold Releasing silicine rubber mold Releasing silicine rubber mold Rubber mold with milled counter mold Rubber mold Rubber mold with milled counter mold Rubber mold Rubber mold Rubber mold Spraying mold release on rubber silicone mold Using OOMOO Smooth-Cast 326 (Liquid Plastic) for final Hex Blocks with Pot Life of 7-9 min and Cure Time of 60 min Rubber mold Part A & B of OOMOO 326 Liquid Plastic Poured Part A & B of Liquid Plastic Poured Part A & B of Liquid Plastic Poured Part A & B of Liquid Plastic Creating second counter rubber mold Creating second counter rubber mold Creating second counter rubber mold Creating second counter rubber mold and creating another Hex Block Creating second counter rubber mold and creating another Hex Block Creating second counter rubber mold and creating another Hex Block Curing Liquid Plastic Curing Liquid Plastic Cured Liquid Plastic Hex Block Liquid Plastic Hex Block Second Rubber Mold Second Rubber Mold Cured Liquid Plastic Hex Block Cured Liquid Plastic Hex Block Third Rubber Mold Third Rubber Mold Third Rubber Mold Molded Hex Blocks Molded Hex Blocks

    Download the Fusion 360 Hex Block Mold 3D model file.

    Click to download Fusion 360 .f3d file.