12. MOLDING AND CASTING

INTRODUCTION

The goal of this assignment is design a 3D mould with the limitations of 3 axis machining, machine it, and cast parts from it.

Students should have:

Explainedd how to made your files for machining

Shown how you made your mould and cast the parts

Described problems and how you fixed them

Included your design files and 'heror shot' photos of the mould and the final object

MOLDING

I used SolidWorks to do my design for the molding. I did a candle with some decoration in two of the four sides, for the limitation of the 3 axis machining. On the top of the mold candle I did two gaps, one will be to put the material inside and the other to the air. Also, in the both parts of the mold I did four interlocking to place them.

To did the desing, it would be better if I did the inclinated walls of the mold, because when I extracted the silicone it would be easier. Another thing you have to keep in mind for the design, is leave enough space between the top of the wax and our design, because when we throw the silicone, cover our design without spill the silicone.

With the program Modela Player 4 I opened the design in stl and I configured it.

1. Model
1.1. Size and oritentation: If it necessary you can scale the design, depending on the material you had. Also you can selected the top surface.
1.2. Origin: Place the origin on our desing.


2. New process creation: define the characteristics of the molding.
2.1. Type of process: Roughinng to remove most the materail and to shape the mold, and Finishing to obtain a better precision on it.


2.2. Select the cutting surface.


2.3. Select the tool.


2.4. Select the area: is possible to mold all the area or chose a specific area.


2.5. Select the type of tool path area: is possible to mold in X, Y or X+Y, the last one it will spend more time; also the countour lines it is very useful to do the Finishing or if there is a round shapes.


2.6. Set the cutting parameters.


2.7. Save the process.


Is possible to watch the endings of each process.

In my case, I did a Roughing and Finishing of all the area with the 3.18 mm diameter tool, and then I did two Finishing one for each side of the mold where I need more detail (the sides of the candle) with the 0.79 mm diameter tool. I did like that because the lenght of the 0.79 mm diameter tool is not enough to do the bottom parts of the mold, for this reason I did a Finishing with the 3.18 mm diameter for all the area.

I put water on the depths of the wax mold, and later I put on a glass, to know the quantity of material that I needed, I weighted it and later thorwn it. In the glass I put the same weight of Smooth On silicone, which I mixed with 5% of catalyst to make the mold. Later, I put it on the wax mold (to avoid getting air bubbles I put it slowly and from a considerable height. After that I used the vacuum machine to remove all the bubbles from inside.

The mold is not perfect, it has some gaps because after put the water I did not dry it. After take out the mold of the wax, I could see the water, which still there.

CASTING

I assembled the two parts of the mold and in the middle I put the wick. I used the wax of the bees to do the candle. I put the wax on a glass in a pot full of scalding water and I stired it with a pencil until the wax was liquid. At this point I thrown in the mold. Later I wait 12 hours before I obtained the candle.

With a cutter I repaired the candle, cutting the excces of wax in the stars and in the top of the candle. Also I cut the thread.

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week 12