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11. Molding and Casting

This week we learned about molding and casting. We learned to design mold with Rhino and mill the mold out with a block of Wax. And then I learned to pour the molding materials into the mold to have a master piece and then casting actual copy later.

Keywords

mold model/master cast/copy

General information

Fabricate a mold Ceramic factories Plastic Factories Glass Industry

3+1 basic types of molds

open face/one part:

  1. wooden mold for mooncakes(cast). The mold is caved in to wood. (cast)
  2. rigid plastic mold for ice cubes. (shape)
  3. Silicone mold for complex ice shapes. (Flexible mold)

Models with No Undercuts and With Undercuts

two part/close box:

silicone rubber mold. An original is needed to fabricate this mold. It can be used for multiple copies. Registration keys for alignment for two part mold, one opening for materials, one opening for air to go out.

Multi-part Mold

Complex shapes

One time mold

slicer for Fusion 360

Material:

Alginate: 10 powder/22ml water

Vacuum-Forming:

HDPE, no undercut.

Pro Tip #1 :

Release Agent: Oil Canola Oil Vaseline.

Two path

roughing toolpath 6mm finishing path 3 mm endmill

Assignment

Our task is to build mold and cast copies.

  1. Positive Mold: made a 3D open face mold with wax+CNC machine 3D model
  2. Negative Mold: use silicon Rubber
  3. Positive Cast: use Drystone(plaster)

Process

  1. box 0 enter 14 0 , 90, 32
  2. scale reference 30 mm
  3. move
  4. persitive
  5. extrudecrve enter
  6. solid extrude select 23 enter
  7. move starting point put on top
  8. shaded view
  9. solid extrud
  10. boolean difference big with surface
  11. solid fillet edge selecting the edges. radius 3 mm set all
  12. make shorter: box make a big box 3mm
  13. boolean difference
  14. move 0
  15. box. top point 55 60 22
  16. move x -10 y 10
  17. move sink inside
  18. boolean difference
  19. move distance from the surface

  20. make bigger box and avoid vertical wall

  21. rectangle the box move new place.

  22. solid extrude taperted (slop -25 5-10
  23. )big box boolean diffrerence.
  24. move majiang to the center use the top point
  25. 5.8 mm at the buttum
  26. make smaller
  27. scales 3d base point middle point to another point 23
  28. boolean union close box
  29. endmill is longer than 20 mm.
  30. combine boolean union
  31. export as stl

Make with CNC machine 1. fix the wax block in a holder. need to push down when tighting. 2. put it into the bed of the machine make sure the was did not move. 3. use wax material. 4. use software: roland modela 5. confirm the size 6. type of milling: better surface finish 7. many flat planes 8. cut top only

  1. step 3 create toolpath
  2. molding wax 148, 100, 32

  3. edit first choose roughing path top, cut area smaller: partial, move to the plate size click apply diameter:6 mm square length 25 mm apply feed rate: the machine knows
    cutting in amount: 3mm if needed interval: 5mm finish margin: need to be more than 0. for roughing path.

  4. edit finishing
    area: plate part: apply flat: round surface ball end ; flat: flat endmill 2mm square(change to 0.5 mm) . yes. coutour: scan line choose or scan line and countour line. up cut. apply cutting para: cutting in amount: 0.5 mm (change to 0.25) path intervel: 0.5 mm finishing margin: 0.00 mm apply create toolpath.

  5. step 4 preview.
  6. step 3. roughing finishing flat: R0.5 ball apply creating toolpath

  7. step 5. perform output to file start cutting.

Move to the Roland Machine

  1. turn on the power.
  2. install endmill: for this design I choose 6mm endmill and R0.5 Ball.
  3. set zero XY and Z.

  4. hold the endmill and tight and adjust the height enough for the holding part.

  5. Open VPanel MDX , start at high speed

  6. set xy original apply
  7. set z axis connect the z 0 sensor scratch the plate use base surface
  8. set z origin using sensor detect
  9. cut - find file

Master

  1. silicon model

  2. cups

  3. part A 60 g +part B 60 g and mixing for a while 1 min scratch the side of the cup and the bottom.

  4. flat surface air bubble on the surface
  5. use the brush take a little silicon painted on the surface of the mold.
  6. stay at high point and stay there for the silicon to flow. make sure no air bubble is created.

Casting

  1. dry stone

File

File stl File ai

Last update: April 27, 2021