8. Moulding and casting¶
In our last weak, we were introduced to moulding and casting which is an essential process in manu industries. The aim was to design something and then use casting process to reach the final design but before that we had to do some research about the materials used for this process. Lets start by presenting a brief overview about casting and moulding.
Introdution¶
What is casting?
Casting is a process in which a liquid material (like molten metal or plastic) is poured into a mold cavity and allowed to solidify. After the material hardens, the mold is removed to reveal the finished product. There are many types of casting which are sand casting which is the most common type, die casting, investment casting and centrifugal casting.
Most common materials
Metals
- Cast Iron
- Steel
- Aluminum alloys
Non metals
- Plastics
- Ceramics
- Glass
What is moulding?
Moulding is a manufacturing process that involves shaping a liquid or malleable raw material by using a fixed frame, known as either a mold or a matrix. The mold is generally a hollow cavity receptacle, commonly made of metal, where liquid plastic, metal, ceramic, or glass material is poured
Most common materials
Thermoplastics
- Polyethylene (PE)
- Polypropylene (PP)
- Polyvinyl Chloride
Thermosetting Plastics
- Epoxy
- Phenolic Resins
Rubbers
- Silicone Rubber
- Natural Rubber
Applications of casting in real life
- Automative industry for making parts such as engine blocks, brake drums and gearboxes.
- Industrial Machinery to make gear housings, pump casings, valves and compressors.
- Tools and Hardware such as hammer and pipe fittings.
The casting process
Task 1¶
As menntioned earlier for the first task we had to choose a product and made a short research about it so I have chose Epoxy resin and the below table will show all the information I have gathered during this research and the final result.
| Product | Epoxy resin |
|---|---|
| Brand | let’s resin |
| Picture |  |
| Material | Polymer |
| Safety | always wear nitrile gloves and safety goggles to protect against splashes, avoid eye and skin contact, follow the correct ratio exactly, pour slowly and evenly to avoid splashes, cover your mold after pouring to protect from dust and debris. |
| Process | Pick the design > Cover the table with plastic or a silicone mat > Make sure the mold is clean, dry, and dust-free > Measure exactly the right ratio > Pour resin and hardener into your mixing cup > Mix slowly and scrape the sides and bottom > Mix for at least 3–5 minutes until fully blended and clear > Pour slowly from one corner or spot to avoid bubbles> Cover your mold with a box or a tray to keep dust out > Let it cure undisturbed at the right temperature (22–25°C usually). |
| Mix ratio | 1:1 |
| Work time | 30-45 minutes |
| Fully cure time | 24-48 hours |
| Cured material state | Solid |
| Technical specifications | Demold Time: 8–24 hours, Full Cure Time: 2–3 days, Viscosity: Approximately 1600 CPS, Hardness: 85D (Shore D), Heat Resistance: Up to 71°C, Maximum Single Pour Volume: 200ml, Mixing: 3 – 5 minutes |
| Real process | I have used a plastic cup and measure it and its weight was 4 g > I poured the resin and hardener each for 6 grams so the total of the cup should weight 16 grams > I mixed for about 3 minutes > I poured the mix slowly > I used a black colour to make it unique > I waited for 24 hours |
| Result |  |
Task 2¶
We were asked to do a simple design, so I have made an initial design but it was not accpeted since it has some distances which are less then 1 mm and there was no curves. You can see the design below and you can see that there are small spaces and especially between the letters.
So, I thought of designing something simpler so I have designed a Game controller
To do the design I had to follow the steps of casting which are creating a positive mold > negtaive mold > positive model (casting).
For this task each indiviual had a machining wax and we used a milling machine to create the positive mold. I have used two drill bits which are 3/32 inch 2FL flat for roughing and 1/32” Square for finishing.