13 . Molding and casting
Task: Molding and Casting Group assignment:
Review the safety data sheets for each of your molding and casting materials Make and compare test casts with each of them Compare printing vs milling molds Individual assignment:
Design a mold around the process you’ll be using, produce it with a smooth surface finish that does not show the production process, and use it to cast parts.
As Part of My Molding and casting week . I was confused with what to make . Then i came to a conclusion of making a Capybara , On the design process it has been changed to Gummy Bear .
For that i used Form in Fusion To Develop a Gummy Bear .
GROUP ASSIGNMENT
DESIGN
I started with a basic sketch of the gummy bear shape in Fusion 360's Form workspace. Using the T-spline modeling tools, I created the characteristic rounded body, stubby limbs, and cute facial features that are iconic to gummy bear candies. The Form workspace was particularly useful for achieving the organic, smooth surfaces needed for the mold design.
Then i have Drawn a boundary with the Given Mould size and extruded It Out and joined .
Now we have to Do CAM
CAM MODELLING
For CAM modeling, I used Fusion 360's manufacturing workspace. First, I set up the stock dimensions and selected appropriate tools for the milling operation. I used a combination of roughing and finishing operations to ensure the mold would have smooth surfaces suitable for casting.
You can find these functions under Setup > New Setup. A tab will open where you can make the adjustments required .
Key settings to configure in the Setup tab include:
- Stock point: Usually set to the top-left corner
- Stock size: Enter accurate X, Y, Z dimensions
- WCS orientation: Align with machine coordinates
- Model position: Center in stock as needed
Now that the setup is complete, we can proceed with configuring the machining operations. There are several key operations we'll need to perform, including face milling, adaptive clearing, and finishing passes. The sequence of operations is crucial for achieving the desired mold quality.
The roughing operation was performed with a 6mm flat end mill to remove bulk material, while the finishing passes used a 3mm ball end mill to achieve the desired surface quality. I carefully optimized the tool paths and cutting parameters to minimize tool marks and achieve the smoothest possible finish for the mold cavity.
For that click on the Drop down Menu down the 3D Tab . Where you could see various Clearing Options . First i have choose to start with Adaptive clearing . For that i have used a 6mm Flat 4 flute end mill. And i have 4000 spindle speed . Its shown below .
Then i have used Pocket Clearing 6 mm . Below i have attached the toolpath settings .
Here you could select the Machinable Boundary . so that machine works only within this boundary .
At the end i have used 3 mm ball end mill to finish
The different clearing operations I performed were:
Adaptive clearing with 6mm flat end mill Pocket clearing with 6mm flat end mill Pocket clearing with 6mm flat end mill Final finishing ( scallop) with 3mm ball end mill for smooth surfaces
You can view the simulation by right-clicking on Program Files and selecting "Simulate," as shown below
This is how the Mould looks like at the end . You could see various similation options in the toolbar (image shown)in the right hand side.
Next step Is to Export The CAM as Shown below
POST PROCESS
During post-processing, I carefully reviewed each toolpath and made necessary adjustments to ensure optimal cutting parameters. This stage is crucial for verifying that all operations will execute safely and efficiently on the CNC machine. I also checked for any potential collisions or inefficiencies in the tool movements that could affect the final mold quality.
Select the Post process button as below to generate the Gcod files that are necessary for the cam process .
Then a Tab like this would be showing . In Operations Tab > You could select all the 6mm Tool path together and make a single gcd . Then you could make another gcd for 3mm .
Once the Gcd is Ready . Copy it into Pendrive and you are ready for Milling .
MILLING PROCESS
After exporting the CAM file, I proceeded to mill the mold using the ProtTrak machine. The milling process took approximately 1 hours to complete, following the toolpath sequence I had programmed. The surface finish achieved was exceptionally smooth, making it ideal for casting.
Here's a flowchart showing the step-by-step process of setting up and operating the milling machine:
This diagram outlines the key steps in setting up and operating the milling machine. Each step is crucial for safe and successful operation. Follow these steps while you are machining.
- Setup Phase
- Power on the machine and verify safety systems
- Tool setup and measurement
- Load 6mm flat end mill
- Load 3mm ball end mill
- Measure and input tool lengths
- Set work coordinates (X, Y, Z zero points)
- Milling Operations
- First Operation: 6mm Adaptive Clearing
- Spindle speed: 4000 RPM
- Check machining boundary
- Second Operation: 6mm Pocket Clearing
- Final Operation: 3mm Ball End Mill Finishing
- First Operation: 6mm Adaptive Clearing
- Monitoring and Safety
- Regular progress checks
- Coolant system monitoring
- Emergency stop accessibility
First i have loaded the wax to be milled . also set the air nozzle aligned to the bit .
Then the next step is like to change the tool
This is me Changing the Tool . Hold the middle portion of the tool and click on out button in the top portion of the machine for the tool to be removed . (Maintain a Good Height for the z axis so that the tool can be removed easily )
2. Setting the Origin
Purpose:
To accurately define the starting point (origin) for machining operations using an edge finder probe.
Steps:
- Insert the Edge Finder Probe into the spindle.
- Switch to the DRO Tab on the machine’s interface.
- Position the Probe: Move it to the left side of the workpiece (e.g., wax block).
- Turn on the Spindle.
- Fine Movement: Press the "F" (fine) button and use the X-axis handwheel to move the probe slowly toward the workpiece.
- Detect Edge: Watch the probe-when it misaligns, stop.
- Set X-Axis Zero:
- Press "ABS SET" on the keypad.
- Add 2mm to the X value (probe diameter is 4mm; half is 2mm).
- Press "ABS SET" again to zero the X-axis.
- Repeat for Y-Axis: Use the Y-axis handwheel and follow the same steps. Add 2mm to Y and press "ABS SET" again.
- Confirm Origin: Press "RETURN ABS 0" and then "GO" to move the tool to the defined origin.
This is me setting zero for x and Y
This is the 6 mm 4 flute tool that i use to clear first . Since i have setted the x and y using the spindle . now its time to remove spindle and place the tool and set the z axis .
Loading and Setting Up G-code
Purpose:
To prepare the machine with the correct toolpath instructions and tool information.
Steps:
- Insert USB Drive with your G-code file into the back of the screen.
- Navigate to "PROG IN/OUT" Tab and select your file to load the G-code.
- Open "TOOL TABLE": Enter details for your cutting tool (e.g., 6mm rough end mill).
Setting Z-Axis Offset
Purpose:
To ensure the tool's vertical (Z) position is accurately referenced for both the base and the workpiece.
Steps:
- Base Z Offset: Set this once for the base reference.
- Workpiece Z Offset: Must be zeroed every time you change the tool.
- After changing tools, use the lever to position the tool tip on top of the workpiece.
- Go to the Z offset tab and select "ABS SET."
- Switch to the DRO tab, select the Z-axis, and press "ABS SET" again.
After this, set the Z-axis by lowering the lever/shaft to touch the tool tip against the wax surface, then zero the Z-axis.
Running and Tracking the Job
Purpose:
To execute the machining operation and verify toolpaths.
Steps:
- Click "RUN" and Press "START": The machine will display a status message.
- Wait for Ready Message: When ready, another message will appear.
-
Press "TRACKING": This mode allows you to verify the toolpath before actual cutting.
- The spindle is off during tracking.
- Use "FWD" for clockwise spindle rotation or "REV" for counterclockwise (choose based on your tool).
- Handwheels control G-code execution (X for coarse, Y for fine).
- Turn handwheels counterclockwise to reverse the G-code if needed.
- Exit tracking mode and select "CNC RUN" when satisfied.
- Select "SHOW PATH": View the toolpath on the screen.
This is the workpiece after machining with the 6mm bit. Next, I will use a 3mm ball end mill for the finishing pass.
This is the Final Finished Part Of my Gummy Bear .(3mm ball end mill 4 flutes)
CASTING
For the casting process, I used silicone rubber to create detailed gummy bear replicas. The silicone material was chosen for its excellent detail reproduction capabilities, dimensional stability, and ability to capture fine surface textures. This particular type of silicone also features good release properties, making it ideal for creating multiple castings without degradation of the mold quality.
STEPS INVOLVED
The first step was preparing the wax master mold for the silicone rubber casting. I carefully cleaned the surface to remove any debris or contaminants that could affect the quality of the silicone mold. Next, I mixed the two-part silicone rubber according to the manufacturer's specifications, ensuring proper ratios for optimal curing properties.
The below image shows the silicone and the hardener that i have used . ratio of the hardener was 30:1000 . I used a ratio Calculator via online to find the ratio for my scenario .
I measured the volume of the mold cavity by pouring water and marking the level with a label. I then measured the weight so I could mix the silicone in the correct ratios.
This is me adding Silicone
Then i have kept in the vaccum chamber so that the air is gone out so that i could cast a perfect Mould .
i have poured the silicon to the Mould and it its kept for Hardening .
After 24 hours of curing time, I carefully demolded the silicone mold from the wax master. The resulting mold captured all the fine details of the gummy bear design perfectly, with no air bubbles or imperfections visible. This mold will be used to cast multiple resin gummy bears in the next phase of the project.
Now that I have successfully created the silicone mold, I mixed the resin components according to the manufacturer's specifications. I carefully poured the resin mixture into the mold cavity, ensuring even distribution to capture all the intricate details. After the recommended curing time, I was able to produce high-quality gummy bear replicas with excellent surface finish and detail reproduction.
STEPS INVOLVED
I received epoxy resin from Aditya, which requires mixing in a 2:1 ratio.
First, I measured the gummy bear mold's volume by filling it with water and marking both the level and weight. Using these measurements, I mixed the epoxy components in the required 2:1 ratio.
The below Photo shows me Mixing In 2 : 1 Ratio .
After measuring and mixing, I poured the epoxy into the mold carefully to avoid any air bubbles. During this process, I noticed that the resin began to set fairly quickly, so timing was crucial. I placed the filled mold in a level position and allowed it to cure completely at room temperature.
I colored the legs and nose by carefully dropping concentrated color pigments using a syringe. This delicate process required precise attention to achieve even color distribution. Using syringes allowed me to add color pigments with excellent control, ensuring consistency in the legs and nose areas. This method effectively prevented any unwanted color bleeding or mixing between different parts of the gummy bear casting. The Below Image shows what i got after adding the colour and the epoxy resin .
RESULTS
This is my Final Results. I got my Gummy Bear with beautiful translucent details and crisp definition. The casting process successfully captured all the intricate features from the mold. The colored elements - the legs and nose - show excellent pigment distribution and add a playful character to the final piece. The epoxy resin provided a crystal-clear finish that really brings out the three-dimensional quality of the design.
Then i also casted in Bismuth . Below is the Image of it .
AFter the Casting Make sure You Disperse the Gloves and GLass that you used correctly in your pre determined dispersal area .
CONCLUSION
Through this project, I successfully completed the entire process of designing, milling, molding, and casting a decorative gummy bear. The combination of digital fabrication techniques with traditional casting methods allowed me to create a high-quality product with excellent detail reproduction and aesthetic appeal. The experience provided valuable insights into material properties, manufacturing processes, and the importance of precise measurements and timing in casting operations.