9. Moulding and casting¶
During this week, I worked on molding and casting a part using the resources we had in our lab. In doing this, I worked on designing a mold and milling it with both a rough cut and a three-axis finish cut on a CNC machine. I then used this mold to cast parts.
Design Work¶
CAD Work¶
I started this by thinking of what I wanted to design. Since I was a little bit behind on past weeks work, I decided I would go with something simple. This way, I would learn how to do this work in a way that is not as time consuming while also teaching myself how to work through this process properly. I decided to cast my initials in a nice looking font.
To do this, I made a box the size of the wax I was going to mill into, 2.342” long x 1.489” wide.
I then extruded the box the high of the block, 0.835”
At this point, I realized that if I messed up my cut on this block of wax, I would have to use a different block, with different dimensions. In order to make this process easier, I decided to use parameters.
After I had my block set up in Fusion 360, I created text of my initials using the sketch feature and added my initials
In order to have the cast go into the mold and be shapped how I want it, I created indents into my design by extruding the text into the block. I hit E for extrude and -0.1 to extrude into the material.
CAM Work¶
In addition to designing our mould, my classmates and I were tasked with working throughout the Fusion 360 CAM and Machining functions. Up to this point, I had never used the CAM function on Fusion 360 before, I only used Aspire, so it was a new learning experience for me. One of my instructors, Dr. David Taylor gave us a presentation on the benefits and the disadvantages of using Fusion to CAM a design. This process was very different for us becasue we had never used this function before. Dr. Taylor also created a workflow on this topic, which I found to be helpful during this assignment. In addition, I used this workflow by Emily A. on the Bantam Tools website.
Using both documents, I was easily able to navigate through the manufacturing process.
I started by entering the Manufacturing portion of Fusion by switching the “Design” in the top left to “Manufacture”
I then downloaded the bantam tools library, and added it to fusion’s tools as a local library by clicking “Manage” near the top right, then “Tool Library”
Next, I went to the new setup menu under the “Setup” tab and defined origin, axises, and the body I would be milling. I also selected the Machine I would use, which is the “Autodesk Generic 3-Axis”
After that, I sent to the stock section and defined the the block as stock size and definied its dimension.
I made the block sit facing up with the side I wanted and created and offset of 0mm in order to reduce the amount of waste material.
The next step was to make ToolPaths for the machine to follow. To do this, I clicked on the 3D adaptive clearing at the top of the page under the 3d tab. I selected to use the 1/16th inch ball end mill disabled the coolant option in the tool tab and stock countours and rest machining in the Geometry tab.
This was my first toolpath, but I had to make another to act as a finishing/smoothing pass. To do this, I essentially followed the same steps as before, but got rid of the stock option.
Post Processing¶
To aid my post processing process, I looked at this documentation by Amanda along with the other two workflows I had.
I selected both toolpaths and hit post process under the actions tab. In the post process window, I changed the file name and made sure not to touch the file number as a fellow fab student advised us not to. I also changed the WCS offset to 1 to avoid processing errors. I then changed the file location and exported the G-Code.
Milling¶
Using my prior documentation and the workflows for the machines in our lab, I started the milling process of the wax blocks. I first downloaded the rough pass g-code I previously uploaded to google drive. I positioned my wax block onto the machine
Configured all the settings, and started the mill of the rough pass.
After both the roughing and the finishing pass, I the wax was ready for casting.
Casting¶
I readied my Mold Star 20T and read the data sheet to see the mixing instructions.
The ratio of the two parts was 1:1, so I filled two cups with the same amount of part A and part B
Before I mixed my parts, I sprayed my wax block with a substance that wouldn’t allow the cast to stick to the mold and enable me to seperate them easier.
I then poured the two parts together and started folding to mix them without foring air bubbles. I had to do this relatively quickly becasue the pot life of Mold Star 20t is 6 minutes, so I had 6 minutes to pour the mixed concentration onto my mold.
I poured the cast onto the wax, and waited for 30 minutes for the cast to cure.
After those 30 minutes were up, I went to check on my cast. I touched it, and it was solid, so I pulled it off the mold.
Even though it was done, I still had to cut off the excess that formed.
After I did that, I had my final product
Group Assignment¶
This weeks group assignment consisted of us experimenting with different types of casts and exploring the advantages and disadvantages of them all. We worked with various different casts, such as Moldstar 20 T, which I used, Task 3, Urethane 666, and more. You can find our work for this week here. We were group A1. Since the process of casting is so messy, We decided to dedicate one group member as the designated photographer for the assignment so the devices would not get all messy and sticky. I was the photographer for all of group A1’s work.
My files for this week can be found here