The first moulding and casting i had done was in my childhood ie making sand cupcakes in coconut shells and building up other structures using the shells. Molds are negative forms that are used to shape casting materials, creating duplicates of the model (object) the mold was made from. The resulting cast will be an exact likeness of the shape of the hollow mold form.
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Moulding
Molding is the process by which we take an object and create an impression of it in some sort of material. Generally, an initially soft material is poured or spread around the object and allowed to harden or set, creating a negative imprint of the object. Moldings can be made in either one piece or multiple pieces. While the type of molding material used depends on the size and shape of that object, some popular options include plaster and silicon.
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Casting
Casting is done once a mold of an object is available. If the mold is made up of multiple pieces, it is put together securely and the casting material is applied. Casting creates an exact replica of the object that was molded, with only some slight sanding needing to be done. Various types of metals are commonly used in the casting process, including aluminum, copper, magnesium, iron, and zinc.
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Process of Moulding and Casting
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Batman gift model
This week i thought i would make use of both bismuth and resin for the moulding and casting works. My plan was to have a gift figure with batman emblem and clear resin for the outer cast
The first thing i had done was to obtain a batman symbol, make an mould for it casting it. Since i was fond of using fusion 360 , i used the same on fusion
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Sample batman symbols can be obtained from grabcad.com , i found so many models which could be downloaded from their website from here
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Doing rough cut in fab modules->load stl->choose 1/8 mm rough mill -> make png -> make rml -> send it
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Begin milling
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Fix the wax cube in MDX 20 mill
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Fix the 1/8 mm ball end mill
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Output obtained after rough milling
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Doing finish cut in fab modules->load stl->choose 1/8 mm finish mill->make png->make rml-> send it
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Begin milling
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Output obtained after finish milling
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Since i need to cast metal, i need a mould that could withstand the temperature of metal, I chose Mold Max 60 which is a catalysed silicone rubber used for applications requiring high heat resistance
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The Mix ratio of the componds is 100:3 by weight from the data. given
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Mix the compounds thoroughly by weighing them using weighing machine
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Pour the mixed compound into the mould
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Silicone rubber mould
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After obtaining the mould , we need to melt the bismuth metal to pour into the mould. The furnace and necessary equipments could be used for the same.The melting point of Bismuth is 271 degree celsius. Put the metal in the cup and heat the furnace near to melting point
Furnace
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Pour the hot metal to the mould and we will obtain as below
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Next step was to design a clear resin structure where this mettalic batman could be placed
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I designed the outer casing in fusion 360
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This is the thing that i intend to built, batman symbol inside a clear resin
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Since i was having lack of time and i was also planning to have a Neopixel LED in the resin, the moulding would take some time before the assignment submission , I thought i would convert my friends mould 'Black panther' to Batman
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I used the below poxy resin for casting the same
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BLACK PANTHER RAISED AS BATMAN
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I had added a neopixel LED at the bottom and programmed it using arduino. The details will be added in the next week documents
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DESIGN FILES FOR DOWNLOAD
FUSION 360 link for download here1 here2
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Group assignment
Smooth Cast
The Smooth-Cast™ 300 Series of liquid plastics are ultra-low viscosity casting resins that yield castings that are bright white and virtually bubble free. Vacuum degassing is not necessary. They offer the convenience of a 1A:1B by volume or 100A:90B by weight mix ratio. The differences between them are pot life and demold time
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Instructions
- Safety - Materials should be stored and used in a warm environment (73° F / 23° C). These products have a limited shelf life and should be used as soon as possible. All liquid urethanes are moisture sensitive and will absorb atmospheric moisture. Mixing tools and containers should be clean and made of metal, glass or plastic. Mixing should be done in a well-ventilated area. Wear safety glasses, long sleeves and rubber gloves to minimize contamination risk. Because no two applications are quite the same, a small test application to determine suitability for your project is recommended if performance of this material is in question.
Applying A Release Agent - A release agent is necessary to facilitate demolding when casting into or over most surfaces. Use a release agent made specifically for mold making (Universal® Mold Release or Mann’s Ease Release® 200 available from Smooth-On or your Smooth-On distributor). A liberal coat of release agent should be applied onto all surfaces that will contact the plastic.
IMPORTANT:To ensure thorough coverage, apply release and brush with a soft brush over all surfaces. Follow with a light mist coating and let the release agent dry for 30 minutes. Smooth-On silicone rubber molds usually do not require a release agent unless casting silicone into the mold. Applying a release agent will prolong the life of the mold.
MEASURING & MIXING... Liquid urethanes are moisture sensitive and will absorb atmospheric moisture. Mixing tools and containers should be clean and made of metal, glass or plastic. Materials should be stored and used in a warm environment (73°F/23°C). Stir or shake both Part A & Part B thoroughly before dispensing. After dispensing equal amounts of Parts A and B into mixing container (100A:90B by weight) and mix thoroughly. Stir deliberately making sure that you scrape the sides and bottom of the mixing container several times. Be careful not to splash low viscosity material out of the container.
POURING, CURING & PERFORMANCE... Pour your mixture in a single spot at the lowest point of the containment field and let the mixture seek its level. This will help minimize air entrapment.Best results are obtained using a pressure casting technique. After pouring the mixed compound, the entire casting assembly (mold, dam structure, etc.) is placed in a pressure chamber and subjected to 60 PSI (4.2 kg/cm2) air pressure for the full cure time of the material.Use this product with at least room size ventilation or in proximity to a forced outlet air vent and do not inhale/breath fumes. Fumes, which may be visible with a significant mass concentration, will quickly dissipate with adequate ventilation. Castings with significant mass may be hot to the touch and irritate skin immediately following cure. Let casting cool to room temperature before handling.
