12. Molding and casting¶
This week, I made a mold for chocolate featuring 6G flagship which I’m belonging in University of Oulu. Gleb Bulygin Fab Academy Alumi 2019 and Ari Vuilia Fab Academy Alumi 2018 are the instructor taught to produce molds with CNC, wax and silicone.
1. Group assignment¶
For group assignment, Ari gave casting lecture to us, Antti and Mona. There are several materials we tested and learned how to cast and what are the differences from the materials. The report is written here.
There are four different materials we tested, Smooth-Sil 940, OOMOO 25, Smooth-Cast 300 and Cement(Creative Knetbeton).
2. Individual assignment¶
In individual assignment, I decided to make a chocolate mold to produce chocolates with 6G flagship logo which I’m belonging to my PhD research. This time I used Smooth-sil.940 for chocolate molding, this is a food safe modling material.
1. 3D modeling by Fusion 360¶
The logo of 6G flagship is transformed to vector data and saved .SVG file. I used Inkscape and trace the Bitmap.
Import the SVG file to Fusion 360’s sketch. Then ready for the letter printing.
Made a 3D model using Create foam - Box then modified into the shape of heart with symmetry.
Put the letters by sketch exclude which imported above.
After finished the 3D design, before making the mold, I tried to make it by 3D printer.
Then I found one mistake, letters were wrong side because of the slope angle of the edge. This chocolate molding, one side mold is enough then smaller side should be bottom, wider side should be upper and the letter sculpture should be located at the bottom side.
So, modified the 3D model, the letters are located on smaller side aspect.
2. Modela, toolpath for Wax milling¶
Production of the mold, to make the silicone mold for chocolate, first the positive mold is needed to create by wax. Wax is very useful material, it’s easily milled by CNC machine but also it can make many details and smooth surface eventually. Another good aspect is that the wax material can be recycle for the next run.
Here is the settings for CNC toolpath, Modela Player 4 was used.
Modelling settings¶
Set > Model, change orientation (x, y and z axes) of the model and set the origin to lower left corner.
Set > Modelling foam select Manual.
Adjust the bottom line.
Make the slope, this time set to 10 degree.
The cutting area is the default of these value.
3mm bit Roughing process settings¶
Here is the settings for 3mm drill roughing process for the shape of heart.
0.8mm bit Roughing process settings¶
Here is the settings for 0.8mm drill roughing process for letters of “6G flagship”. In Fablab, the minimum size of milling was 0.8mm, but 0.8mm setting couldn’t apply to this time design of letters, so this time was set by 0.6mm profile and tried.
Finishing process settings¶
Here is the settings for finishing, to make the smooth surface of the wax mold.
The settings result can be seen by simulation.
Positive mold by Wax, Roland SRM20 milling¶
Making a positive mold used by wax material.
Set the wax into CNC machine, using masking tape for both wax and the stage, then used hot melt to fix the wax into the stage.
3mm Square bit (left) for roughing and ball bit (right) for finishing.
0.8mm milling bit.
To make sure the zero position of Z axis, put the bit to center of the wax material.
After roughing process of 3mm milling bit.
After roughing process of 0.8mm milling bit of letters.
After finishing process, made very smooth surface.
Completed the wax positive mold!!
3. Negative mold by Silicone casting¶
Making a negative mold by silicon. This time is for chocolate, for food, the mold material is used by Smooth Sil 940.And the silicon producing operation carefully according to the safety datasheet.
According to the instruction of 100A:10B proportion, I used 150g of A and 17g of B (2g over but no problem).
Vacuumed air inside of silicon for 15 minutes, the pot time is only 30 minutes so need carefully to check the time with quality.
Used 150g of the main material but it was too much, 100g was the proper quantity for this size of mold.
After 24 hours cure time, the negative mold was done!!
But the problem was on letters, the silicon gel couldn’t enter to some letters. It can be solved by using some sharp sticks when put the silicon to wax for those small details and edges.
4. Casting chocolate¶
Make a chocolate!
Again check carefully the instruction for food related applications.
This is not baking mold for cookies etc, but needs to avoid the hygiene risk Before putting chocolate. After cured silicon completely, bake the silicon mold in oven by 90 degree for 2 hours.
Crashing chocolates were put into the mold and 70 dgree heating at oven then melt the chocolate.
After melt completely the chocolate, put into refrigerator for over 1 hour,,,, then chocolate done!!
Some damaged but very nice shape with logo of 6G flagship! Satisfied!!
reflection¶
This was the first time for me to make the molding process with positive and negative molds. Good thing was that I made the shape by 3D printer beforehand, it could make a quick review of shape but also I found a modification point on the 3D design. Some learning point was for silicon molding, some letter shapes are not good and needed to use some sharp stick to make sure the material entering into the details design. However, overall satisfied result and it was fun activity.