11. Molding and casting¶
General Info¶
Nueval¶
- Global evaluation
- App screenshot -> English
Output devices¶
-
Parts
-
AVR-1
- megaTinyCore
- Arduino Board manager
- I2C (TWI) support
- You must be sure to use external pullup resistors on the SDA and SCL lines if the devices you are connecting do not have those on board
- 10k Ohm x2
- sample
- megaTinyCore
Assignment¶
Group assignment:¶
Note
review the safety data sheets for each of your molding and casting materials, then make and compare test casts with each of them
Individual assignment:¶
Note
design a mold around the stock and tooling that you’ll be using, mill it (rough cut + (at least) three-axis finish cut), and use it to cast parts
preparation of 3D modeling¶
- MDX-15
- work area: 152.4mm × 101.6mm × 60.5mm
- Machinable wax
- size: 152mm x 92mm x 39mm (real size is smaller)
- Endmill
- 0.1250” DIA 4FL SE LONG AlTiN 1/8
- Size: 1/8”=3.175mm
- OverAll Length: 2-1/4”(2.25”) =57.15mm
- 0.0625” DIA 2FL SE AlTiN 1/16
- Size: 1/16” =1.5875mm
- OverAll Length: 1-1/2”(1.5”) =38.1mm
- 0.1250” DIA 4FL SE LONG AlTiN 1/8
-
Design to think…
- XY size: real wax size
- Final Part size < (wax size - wax_wallx2 - mold_wallx2)
- distance between bumps凸 & dents凹: tool size > 1.58mm(1/16”) > 0.79mm(1/32”)
- Z depth
- tool: 1/16_endmill_lemgth=38.1mm -in_collet_lenght=10mm = 28mm
- machine: MDX-15_z=60.5mm - Wax_height_39mm = 21.5mm
- 2 sides mold: 21.5mm each = 43mm_max
- 1 side mold: 21.5mm_max -> 9 degrees tilt to prevent hitting collet
- tilt image
- tilt degree calculation
- Registration (for alignment)
- ref. How to Make Molds
- Registration Key
- nest (recommend)
- pour spout (lower position)
- air vent (higher position)
- part line -> deburring
- XY size: real wax size
-
Process
- 3D modeling
- Fusion360
- Tool Path
- Modela Player4 (Windows)
- Virtual Modela (Windows)
- Rough cut (1/8”)
- Finish cut(1/16”)
- cast silicone molds from wax
- cast final part from silicone molds
- 3D modeling
TODO: Group assignment¶
review the safety data sheets for each of your molding and casting materials,
materials¶
-
machinable wax, modeling wax
-
Silicone rubber
- Mold Star 31T 0.9KG Trial Kit
- Smooth-on SDS
- SDS_JP
- Mix ratio by Volume: 1A:1B
- Mix ratio by Weight: 1A:1B
- pot life: 5 min
- cure time: 23 min
- color: Translucent
- Share Hardness: 30A
-
Urethanes resin
- Smooth-Cast 320 0.86KG Trial kit
- Smooth-on SDS
- SDS
- Mix ratio by Volume: 1A:1B
- Mix ratio by Weight: 100A:90B
- pot life: 3 min
- cure time: 10 min
- color: Off white
- Share Hardness: 70D
-
So-strong
- Color Tints for Urethane
- Smooth-on SDS
- 0.01% to 3% of total system weight
make and compare test casts with each of them
- test cast
- safety
- ventilation
- protection
- glass
- groves
- disposal
- finish chemicals reaction before dispose -> heat
- dispose cups and Stir bars directly into bin
- change groves
- do not touch any uncovered place, chair, desk…
TODO: Individual assignment¶
design a mold around the stock and tooling that you’ll be using,
-
negative/positive
- 3D modeling process
- sample
- design final part (positive)
- design molds to make final part (negative)
- design wax to make molds (positive)
- casting process
- pour liquid silicone rubber into wax to cast molds (negative)
- pour liquid resin into molds to cast final part (positive)
- 3D modeling process
-
Fusion360
- Final_part
- model as any way
- Silicon_mold
- model Silicon_block
- combine > cut
- Silicone_block - final part = Silicon_mold
- Wax
- model Wax_block
- combine > cut
- Wax_block - Silicone_mold
- add
- Pour Spout
- Air vent
- Registration key
- Final_part
mill it (rough cut + (at least) three-axis finish cut), and use it to cast parts
Assessment¶
-
I want to only make a wax mould, and cast something in it. Is that acceptable?
- Answer: Only after you learn and go through the 3 step process. To break the rules, you have to master the rules.
-
Can I 3D print the mold? Can I do a lasercut?
- Answer: No, for this assignment you must mill the mould using a CNC milling machine. After fulfilling the requirements, please go ahead and experiment other techniques for fabricating moulds.