Week 12  ( April. 18, 2017 )

Molding and Casting

This week we will learn the process of molding, different techniques to do the same, casting using it etc. I haven’t molded much except once during prefab which didn’t work out well.

• •.Molding : It is a hollow solid structure into which a liquid, which eventually hardens, is poured to which forms the shape of the mold.  

• •.Casting: It is the counter of molding. It is the process of pouring the liquid material and the rest which I have mentioned above.  

Molding and casting processes are used widely for making materials in plastic, ceramic, glass, metals etc. Also have this weeks class note as references.

• Assignment

design a 3D mold, machine it, and cast parts from it

Designing in Tinker cad

 

Molding

Molding can be done in many ways using a variety of materials. The common ones are

• •.machinable wax  

• •.rigid foam  

• •.rigid foam  

• •.silicone  

• •.plaster  

• •.metal  

• •.casting rubber etc.  

Designing

I decided to make a simple 3D design in TinkerCAD

I exported my design in to STL file which is 3D.

ArtCAM conversion

I need to convert my 3D design in to CNC  machine understanding code after generating the tool paths in order to process my design in wax.

Firstly I imported my 3D file into Artcam and placed in center of the mold material dimension which I  defined

After that I convert my design in to 2D using greyscale conversion. So that this is converted in to vector. Also defined the space for the cut to start.

After that I subtracted, zero reseted and defined the starting height of cut in the shape editor menu for defining how the cutting and processing will work

Then I generated the 3D and then defined the tool paths for rough cutting as well as Smooth finishing.

How to generate tool path

Roughing tool path

For the generating tool path I select z level roughing in here we are using 3mm roughing tool that is why I select End mill 3mm.then I generate and i save the tool path.

For the finishing tool path we are using v bit,for that I did the same method  of roughing tool then I saved both of them .nc file for the milling.

After saving the tool paths, I fixed the wax in the CNC bed and started to mill the wax.

Molding process :

Using water to fill the milled wax in order to measure the volume which was 40 ml.

 

 

So I need 20 ml of RTV2 Liquid Silicon Rubber, Solvent A (RTV1510-A) and 20 ml of Solvent B (RTV1510-B) because the mixing ratio is 1:1. and I added 2 ml extra of each solvent to cover any loss.

After that I poured the mix in the milled wax gently to allow the entrapped air to exit and avoid any bubbles and put small wooden sticks to help in removing the mould and waited for few hours to cure.

Casting

There are resins called Amazing Casting Resins consists of two materials Resin A and Resin B which has to be mixed in 1:1 ratio.

 

 

With process similar to the one above,poured the mix in the mould

 

and waited for 15 minutes and this is the final result.

 

This is the result of the molding and casting. It was a fun experience and easy. We can make soaps, cake and cookies using this method.

Files STL file