10. Molding and casting¶
Group assignment :
- Review the safety data sheets for each of your molding and casting materials
- Make and compare test casts with each of them
Individual assignment :
- Design a mold around the stock and tooling that you’ll be using
- Mill it (rough cut + (at least) three-axis finish cut)
- Use it to cast parts
Group assignment¶
Link to ULB Group : link
For the group work, I analysed the products available to me. We received Crystal Clear resin, RTV Silicone, but also classic and phosporescent colorants and a release agent.
Crystal Clear resin datasheet¶
Transparent casting and coating. Two component colourless epoxy system.
W241: Recommended maximum casting thickness 100mm
W242: Max. recommended casting thickness 10mm
Colour: colourless
Viscosity at mixing: 650-950
Density: 1.10-1.14
Mixing ratio: 100:45
Potlife with W241: 75-95min
Potlife with W242: 35-45min
Demoulding time with W241 : 36-48h
Demoulding time with W242 : 18-24h
Danger
H315: causes skin irritation
H317: May cause skin allergy
H318: Causes serious eye damage
H411: Toxic to aquatic organisms, causing long-term adverse effects
P261: Avoid breathing dust/fume/gas/mist/vapour/air
P273: Avoid release to the environment
P800: Wear protective gloves/protective clothing/eye protection/face protection
P305+P351+P338: In case of contact with eyes: rinse cautiously with water for several minutes. Remove contact lenses if present and easily removable. Continue rinsing
P310: Call a poison control centre or doctor immediately.
Silicone RTV¶
RTV silicone is suitable for the reproduction of figures, artefacts and similar objects. It is a 2-component material consisting of RTV and RTV hardener. Curing at room temperature.
Technical data with RTV hardener
Colour: White
Hardness Shore A:25
Demoulding after 24 hours at 23° CPréparation du matériel
Potlife: 36-60min
Mixing ratio by weight: 100:5
Tensile strength: 2.8
Elongation at break: 380%.
Tear strength: 2.0kN/m
Linear Shrinkage: <0.8
Relative density: <0.3%.
Relative density: 1.08
Viscosity: 20.000-25.000 mPa
Individual assignment:¶
Design on Fusion 360¶
I have made a name tag for the fablab. It is small but complete enough for the demonstration. After looking at the time estimates for the machine, I decided to make the part on the “big” digital milling machine.
![](../../images/week10/fusion01.jpg)
First step, roughing with a 3mm milling cutter
- Optimal load : 1.2mm
- Minimal cutting Radius : 0.3mm
- Maximum Roughing Stepdown : 1mm
- Fine Stepdown : 0.1mm
![](../../images/week10/fusion03.jpg)
![](../../images/week10/fusion02.jpg)
Then roughen with a 1mm milling
- Optimal load : 0.4mm
- Minimal cutting Radius : 0.1mm
- Maximum Roughing Stepdown : 0.5mm
- Fine Stepdown : 0.05mm
![](../../images/week10/fusion05.jpg)
![](../../images/week10/fusion04.jpg)
With a 0.6mm milling
Contour
- Maximum Stepdown : 0.2mm
![](../../images/week10/fusion06.jpg)
![](../../images/week10/fusion07.jpg)
Pocket for b and a : 0.6mm
- Maximum Stepover : 0.57mm
- Finishing stepdown : 0.1mm
![](../../images/week10/fusion08.jpg)
![](../../images/week10/fusion09.jpg)
3d surface finish with 0.6mm milling
- Stepover : 0.1mm
- Maximum Stepdown : 0.2mm
- Nb Stepdown : 1
![](../../images/week10/fusion10.jpg)
![](../../images/week10/fusion11.jpg)
![](../../images/week10/fusion12.jpg)
![](../../images/week10/fusion13.jpg)
Download :
Work in CNC Mekanika¶
A first pass with a 3mm milling
![](../../images/week10/cnc001800.jpg)
![](../../images/week10/cnc002800.jpg)
![](../../images/week10/cnc003800.jpg)
A second pass with a 1mm milling
![](../../images/week10/cnc004800.jpg)
![](../../images/week10/cnc005800.jpg)
We finish with a 0.6mm milling
![](../../images/week10/cnc006800.jpg)
![](../../images/week10/cnc007800.jpg)
![](../../images/week10/cnc008800.jpg)
![](../../images/week10/cnc009800.jpg)
I am quite happy with the result
Mould creation¶
Let’s go for the casting of the part.
Preparation of the material
![](../../images/week10/mold001800.jpg)
![](../../images/week10/mold002800.jpg)
Weighing is extremely important. The ratio of 100:5 must be respected.
![](../../images/week10/mold003800.jpg)
![](../../images/week10/mold004800.jpg)
![](../../images/week10/mold005800.jpg)
Mix for a few minutes without making bubbles
Spray is applied to facilitate demoulding in the final phase
![](../../images/week10/mold006800.jpg)
The silicone must be cast to make the mould
![](../../images/week10/mold007800.jpg)
![](../../images/week10/mold008800.jpg)
![](../../images/week10/mold009800.jpg)
![](../../images/week10/mold010800.jpg)
![](../../images/week10/mold011800.jpg)
We wait about 24 hours to see the result
![](../../images/week10/mold012800.jpg)
![](../../images/week10/mold013800.jpg)
![](../../images/week10/mold014800.jpg)
Creating resin parts¶
Danger
obligatory protection
![](../../images/week10/protection01800.jpg)
![](../../images/week10/protection02800.jpg)
Weighing is extremely important. The ratio of 100:45 must be respected.
we start pouring
![](../../images/week10/cast001800.jpg)
![](../../images/week10/cast002800.jpg)
![](../../images/week10/cast003800.jpg)
![](../../images/week10/cast004800.jpg)
A few drops of dye are added
![](../../images/week10/cast005800.jpg)
![](../../images/week10/cast006800.jpg)
We add the second component
![](../../images/week10/cast007800.jpg)
![](../../images/week10/cast008800.jpg)
![](../../images/week10/cast009800.jpg)
Mix well to avoid bubbles
![](../../images/week10/cast010800.jpg)
![](../../images/week10/cast011800.jpg)
![](../../images/week10/cast012800.jpg)
We prepare the parts to be moulded and we cast our mixture
![](../../images/week10/cast013800.jpg)
![](../../images/week10/cast014800.jpg)
![](../../images/week10/cast015800.jpg)
![](../../images/week10/cast016800.jpg)
We heat to make the bubbles disappear.
To remedy the bubbles, several solutions are available to us:
1 - Pour really slowly without any sudden movement (not the easiest)
2 - Use a vacuum box (we don't have one at the fablab)
3 - Heat the resin until the bubbles disappear. (this last option was used here with a "thermal stripper")
![](../../images/week10/cast018800.jpg)
Final Result¶
![](../../images/week10/demoulage000.jpg)
![](../../images/week10/demoulage001.jpg)
![](../../images/week10/demoulage002.jpg)
![](../../images/week10/demoulage003.jpg)
![](../../images/week10/demoulage004.jpg)
![](../../images/week10/demoulage005.jpg)
![](../../images/week10/demoulage006.jpg)
![](../../images/week10/demoulage007.jpg)
![](../../images/week10/demoulage008.jpg)
![](../../images/week10/demoulage009.jpg)
![](../../images/week10/demoulage010.jpg)
![](../../images/week10/demoulage011.jpg)
Bonus¶
In an art shop, I found some silicone moulding compound. It is ready in 5 to 10 minutes and the mould can be used 50 times.
![](../../images/week10/PEBEO.jpg)
Mixture, 1/1
So I made several moulds to carry out several tests. The first one, with a phosporescent powder, the second and the third with different dyes and the last one with wax
![](../../images/week10/resinebonus02.jpg)
![](../../images/week10/resinebonus06.jpg)
![](../../images/week10/resinebonus03.jpg)
![](../../images/week10/resinebonus07.jpg)
![](../../images/week10/resinebonus08.jpg)
![](../../images/week10/resinebonus04.jpg)
![](../../images/week10/resinebonus05.jpg)
![](../../images/week10/resinebonus09.jpg)
Result¶
![](../../images/week10/resineend1.jpg)
![](../../images/week10/resineend2.jpg)
![](../../images/week10/resineend3.jpg)