Molding & Casting

Group Assignment * Review the safety data sheets for each of your molding and casting materials, then make and compare test casts with each of them

I have use Certi-Vex CE 210 which is a two component, 100% solids, solvent. structural construction multi purpose epoxy adhesive. For the EPOXY product I found a technical data sheet with limited safety instructions. * Use gloves during use and wash your hands after use. * Avoid eating, drinking or smoking while use

Individual assignments In this assignment I have to: * 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.

In this assignment I decided to make a cover for my circuit when attached to the final project model. 3D Design:

I used SOLIDWORKS to design the cover. First I draw a rectangle and use extruded boss to extude it and create a solid object.

w12_2 w12_2

Next, I draw four circles for the skrews and use extuded cut to make holes.
w12_4 w12_2
w12_4
Again I draw another rectangle and use extuded cut.
w12_7 w12_8
w12_9

After that I used Aspire software to create G-code for my CNC.

w12_11
First step is importing 3D model as STL format and change the object position.
w12_12w12_13
next, I choose 3D Roughing toolpath tool to engrave the mold. In this step I choose the drill bit tool (I used end mill 2 mm) then press calculate.
w12_14w12_15
w12_16
Aspire simulates engraving process as shpwn in this video:

I used a melted wax to make a mold. I attached the mold to the CNC by using a small screws.

w12_18
To avoid any damage in my mold I measured the drill bit length before starting.
w12_19w12_20
Now, CNC router is ready now. It is the time of Mach3Mill software to control the machine.
w12_21
Set the x-y-z of the machine and start:
w12_22 w12_23
w12_24
Finally, I get:
w12_26
After cleaning:
w12_22 w12_23
Now it the mixing time, I used selecon and cornstarch and mix them with 1:2 ratio.
w12_22 w12_23
w12_4
Now it is ready:
w12_33
Then I mixe epoxy resin:
w12_22 w12_23
I added some acrylic to color the resin:
w12_37
And mixing for three minutes.
w12_38
Now, pour the epoxy in silicon mold:
w12_39 w12_40
And after waiting for 24 hours:
w12_41
finally, my mold was failed. I will try again.

Second attempt is to design a mold in shape of diamond for chocolate. I used a tutorial video to draw a diamond in SolidWorks. First, I draw Polygon with 16 Sides, then I used Boss-Extrude tool.

w12_42 w12_43
Then I used Convert Entities tool to add same shape above the first, again used Boss-Extrude.
w12_44 w12_45
Repeat same steps with different parameters.
w12_46 w12_47
To make a mold shape, a tutorial video is very helpful.
w12_48
After saving as STL file, I used 3D printer to print two parts of the mold object.
w12_50 w12_51
I filled the mold parts with melted chocolate and put it in refegerator. After short time I remove one side and get:
w12_50 w12_51
IN subtractive manufacturing processes first step is roughing cut. In this step bulk amount of material is quickly removed from workpiece. A higher feed rate is used. It cannot provide good surface finish and close tolerance.
w12_48
After roughing cut, a finishing cut is carried out to improve surface finish and dimensional accuracy. Very low feed rate and depth of cut are employed. Stock removal rate reduces in finish pass but surface quality improves.
w12_48
This video shows the two processes:
vacuum de-gassing process: In some cases we need to vacuum de-gassing. Vacuum degassing is a process to remove trapped air bubbles easily from silicon mixture using a vacuum chamber and a vacuum pump as shown in this video. Degassing is a crucial step after mixing (sometimes degassing is also required after casting) to eliminate residual pores in the slurry. These pores can be introduced during either mixing or the chemical reaction, or they can form as a result of entrapped air during casting. Place your solution in a side-arm flask with a stir bar and use a rubber stopper to seal off the top. Place the flask on a stir plate and turn the plate on so the stir bar is spinning at a medium speed. Vacuum chambers are for removing air from high viscosity materials like silicone rubber before pouring. They are also ideal for for making bubble free castings.

Download Links