Molding and Casting

1. Assignment

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
Individual assignment:
design a 3D mold around the stock and tooling that you'll be using,
machine it, and use it to cast parts

2. Plan

Prepare material:wax,Model plaster, plywood
Design:use fusion 360 to design the model and the mold
Process: use 3 axis machining to mill the wax
Mold:cast Silicone rubber to make the mold
Model:cast the plaster to make the model

reference from Krisjanis Rijnieks 's page

3.Design:

In this step I use fusion 360 to design the model ,it is a simple logo of our makerspace NexMaker. The following points need to remember

Most of the design is similar with fusion360 design, in this part I just write some special design

3.1 Logo exturde

Use the INSERT➡️ Attach Canvas commond to input logo information;
Use the SKETCH➡️Creat Sketch commond to make the sketch according to the logo picture;
Use CREAT➡️Extrude commond to make the 3D information of logo

3.2 Build the wall

I need to make wall to avoid the liquid material (in this case it is Silica gel)leave away ,so I need to build a base and wall to keep it, we must make sure the wall high then the model ,similar with the picture in the following last picture. In this case ,the gas between model and wall in the direction of high is 5.5mm

3.3 Key

The key is used in the cast which need two mold connect together. The function of key is to keep them connect together in right position. So I design a couple of key which fit together . The position of key is very important, so I put them in mirror

3.4 Chamfer

We use 3mm milling cutter to do the finish process, and the length of cutter is 5mm,it is the same as the model.So the handle of cutter has the risk to impact the model .I design a chamfer to avoid the risk it is close to the distance of model, and it has risk to impact the model

4. Use 3 axis machining to mill the mold

4.1 Prepare

material:I use the F-14 wax to make the mold ,and the size of the wax is 160X90X35mm
Equipment:MDX-40A CNC Mill/CNC Machine
Cutter: I use two kind of cutter: 3mm square cutter for rough

4.2 Get data

I output stl from fusion in the command of MAKA ➡️3D print ,and then open it in the Rland software(MODEL PLAYER4)

4.3 Setting in software

Use the command SET➡️Model to position the model
In the select top surface, I choice one which should meet the requirement
Click "OK"
In origin page , I choice edge point as origin point, because it is more easily to define than middle point
OK ,we can find the position in the software

4.4 Rough process

In rough toothpath, we need to choice the type of processing, and use roughing command;
Select the cutting surface, I choice the default surface, so directly click theNext button;
Choose the tool ,according to my cutter, and real design, I use 3mm square cutter;
Set the cutting area and depth , I goPartial and check the parameter.in this time I change lower left x=0.5,y=0.5,in the meantime minus 0.5mm on upper right, so the finial x,and y is x=57.5,y=65.24(origin size is x=58 y=65.74)
Choose the type of path:in this step we direct usecontour line:up cut
Set the cutting parameter: we need to care about
- Cutting in amount: 2.5,it means every layer we need to cut 2.5mm depth
- Path interval:it should less than the diameter of cutter(in this case is 3mm)
- Finish Margin:I choice 0.2mm, it mean the process will leave 0.2mm for finishing process
Choice OK to update it ;

4.5 Finish process

In this step is similar with rough process, and the main different is some parameter I choice. So I just show some difference

Tool: I choice 1.5mm square cutter and the material is High speed steel
The type of tool path: I choice scan lines :x (x or y is the same and it can make sure the high quality than contour line)
Set the cutting parameters
- Change x,y,z speed slower fromxy speed:8➡️5, z speed:7➡️4.5 ; Spindle speed from 9000 to 9800( low moving speed and high spindle speed can make sure high quality)
- Path interval:the less the better,and it must less than 1.5mm(the diameter of cutter now is 1.5mm)
- Finial margin should go to0and it can make the size the same as design

4.6 Check

We can click the red button on the last figure and check the path and other detail information ,if it has some risk ,we should edit the setting again ,if it is OK ,go to next step.

4.4 Load material

I use Double-sided tape to connect the wax on the platform of CNC machine,In this step ,we need to make sure the horizon of surface and fix firmly on the platform

4.5 Fix cutter and ill it

Open the software :"Roland Vpanel for MDX-40A";
Move x,y coordinate('4','5',button) , to define x,y coordinate ;
Click 1 button to open the spindle and change the spindle speed in form2
Low down z slow, it is OK ,When cutter just touch material;
Use Set➡️XYZ Orgin➡️Apply.
Then rise Z to avoid impact.

I use 3mm square milling cutter in rough process, and use 1.5mm square milling cutter in finish process. So I Load the cutter and then process the material.It is the same as CNC part. After clean machine and wax,I get this mold.