12. Molding & Casting

Reflection

I learnt how to Mold. Steps includes designing and making a mold, selecting materials, using CNC milling or 3D printing to create parts.

Key terms include mix ratio where items are to be mixed, pot/working life indicates how long the resin is workable before it starts to harden; Cure time is the time of hardening the material.
Quote from internet: 3D milling refers to the CNC’s ability to move X, Y and Z all at the same time.
Cast is the harden object taken from the mold. The objects can have different hardness measured by Shore Hardness.
Curing is not a final fantasy term to heal your ally. It means process of hardening.
Silicone Mold release did not work well for my chocolate mold project.
Chemistry Student, happy reading your datasheet.

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. Done in 2022.
compare printing vs machining molds: refer to section on comparision below instead of group assignment as I did this section myself in 2024.
2022 group assignment link

Individual Assignment

☑ Linked to the group assignment page and reflected on your individual page what you have learned
☑ Reviewed the safety data sheets for each of your molding and casting materials, then made and compared test casts with each of them
☑ Documented how you designed your 3D mold and created your rough and finish toolpaths for machining, including machine settings
☑ Shown how you made your mold and cast the parts
☑ Described problems and how you fixed them
☑ Included your design files and 'hero shot' of the mold and the final object

What I did

My individual assignment is to develop a design model for chocolate and employ CNC milling and 3D printing to fabricate a corresponding mold. I utilize the Roland MDX 50 CNC milling machine and Bambu Carbon X1 to fabricate.

V2 My Digital Object Mold & 3D Printing or Milling

First I started with designing the mold. Picture below shows the designs I made. I remade on instructor's suggestion.
Vector Tools

I made a sculpture using Forger on Ipad.
Then I exported the file.

Next I import mesh file into F360, repair mesh, closed mess hole and converted the mesh to solid.

I boolean subtract on rectangle to get the 3D model.
I exported the mold
Vector Tools

Then I set the Bambu Settings for 3D printing.

Then I reprinted at an angle and lower layer height of 0.08mm so that the fdm quality is higher.

V1 CNC Milling

First I started with designing the mold in Tinkercad by dragging the shapes I want and export as stl file.
Vector Tools

I open the file in SRP Player and select the setting of size and orientation of stl as shown in picture below.

I select the Milling type. (Better Finish, many curve surfaces so that it is 2.5D). Vector Tools

I select the workpiece size and align model to top.

I select the toolpath settings for roughing and finishing.

I create the toolpath Vector Tools

I continue to simulate and start the cutting after I adjust the location for cutting. And shown is the part after washed.

Reading EasyMold Again

First I read the Datasheet and listed the key points of EasyMold Silicone Rubber – Platinum Cure Silicone below here..
Vector Tools

Category	Details
Material Type	Platinum cure, two-component silicone rubber
Properties	Odorless Non-toxic FDA compliant Food-grade
Applications	Castin’Craft Clear Casting Resin EasyCast Clear Casting Epoxy Wax Baking goods Chocolates (the reason why I am buying it) Ice cubes Soap Plaster Air dry clay Concrete Low melt metals
Key Properties	Brushable/Pourable 45 minutes to 1 hour working time 24-hour cure time (adjustable with heat) Extremely fine detail reproduction with no shrinkage Self-releasing (no mold release agent required for most applications) Heat resistance up to 400°F Strong, flexible, reusable molds No vacuum equipment required
Handling	Keep out of reach of children. Avoid contact with clothing and skin. Provide adequate ventilation. If ventilation is inadequate, wear respiratory protection. Wear appropriate personal protective equipment, such as gloves and safety glasses. Observe good industrial hygiene practices.
Storage	Store in a tightly closed original container. Keep in a dry, cool, and well-ventilated place. Store away from incompatible materials, such as strong oxidizing agents and items containing sulfur.
Personal Protective Equipment (PPE)	Wear impervious gloves, such as butyl rubber or nitrile rubber, to avoid skin contact. Wear chemical safety glasses or goggles to protect your eyes. Ensure an eye wash facility and washing facility are available in the work area.
First-Aid Measures	Eye Contact: Rinse with water for several minutes. Remove contact lenses if present and easy to do. Seek medical attention if irritation persists. Skin Contact: Wash skin thoroughly with soap and water. Seek medical attention if irritation develops. Inhalation: Move to fresh air. Seek medical attention if feeling unwell. Ingestion: Rinse mouth. Do not induce vomiting unless directed by a medical professional. Seek medical attention if feeling unwell.

Mixing EasyMold

I mixed the Type A and B in equal parts by volume and mix until uniform color and wait for the mold for 24hours. Shown are the results of different mold Vector Tools

Preparing the Chocolates

I heated Chocolate and poured it into the mold. Retrieve my chocolate and open new one. Since my job is to compare items made from CNC and 3D printed mold. Both taste equally yummy. But honestly, the comparision is in table of next section. below is picture of chocolates made. Vector Tools

Comparing the process for making mold and products via CNC and 3D printing

For this project, I had CNC mill on Acrylic and 3D print using PLA, the mold are made by EasyMold Silicone.

Feature	CNC Molds	3D Printed Molds
Material	CNC have quite alot of materials to work on. A material made of wood or acrylic looks nice and feels safe to make the food. but spoke to some friends in food science they mention acrylic may leech chemicals.. and wood may have bacteria growth. limited by thickness of material to be cut	3D printers is hard to find a food grade filament in normal fabspaces. thermoplastics or resins limited by the print volume
Surface Finish	Very smooth, high precision finish esp with 2.5D Milling Requires less post-processing	Layered surface, may require post-processing if picky chocolate lovers. Finish quality depends on print resolution 0.08mm.
Complexity	Limited by tool access and design constraints Good for simple to moderately complex shapes	High complexity, including intricate geometries Supports complex internal structures, but when making small chocolates, intricate geometries may not be visible
Cost	High initial setup cost as CNC tends to be more expensive than 3D printers Cost-effective for high-volume production as it is faster to mill than 3D print at higher resolution subtractive making so wasting of materials.	Lower initial cost Cost-effective for low to medium volume production addictive manufacturign so less materials wasted.

Original Design Files and Source Code

- STL for Beaker - STL for Figurine

Design for F360 Figurine

Design for Tinkercad