Plaster mold castings are machined castings that combine gypsum and enhancing compounds to create a mold. A pure plaster is not very strong; therefore, a combination of plaster and additives are used to enhance castability, permeability, dry strength, and green strength. For instance, magnesium oxide or talc is sometimes added to reduce setting time and avoid cracking.
You’d think this was a simple answer – plaster, right? It gets a little more complicated. Machined castings are made in different ways. The plaster pattern is made of either metal or rubber. Next, it is often coated with an anti-adhesive material to avoid it sticking to the mold.
Machined castings can get expensive and large. With plaster castings, it's easy to change, reuse, and remold. They are also pretty affordable. If you want to get a machined castings quality product without gaps around the mold, and at an affordable price, plaster casting is the perfect option.
Machined castings require a lot of attention to detail to get the result you want. Once you have determined the parting line, or where the two halves of the cast meet, the plaster is combined and the pattern is covered with an anti-adhesive. The plaster is then poured into the pattern and shaken, allowing the plaster to fill the gap. Finally, it is left alone in the cast for about 15 minutes to set.Once you feel comfortable with the mold, it is heated at high temperatures to remove all the excess water. As soon as the metal hardens, the plaster is removed from the cast and the finishing process begins.
The final step is the most fun! It includes blasting, heat treating, grinding and cleaning. If you want to get quality castings or talk to an expert, contact Ferralloy Inc. now!
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