12. Molding and Casting¶

This week was full of hard physical work and brainstorming on doing something interesting and big. Mostly we’ve got acquainted with sand casting. Here it uses sand as the mold material.

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Useful links¶

Sand Casting¶

At first for producing an object we need a pattern of it. That pattern can be made from wood, metal, or even expanded polystyrene. The pattern must be slightly larger than the finished product due to contraction during solidification. After we need to mold the form. For that we use sand, that’s why it’s sand casting. The sand is being mixed with clay or material that is more soft. It after helps easier to take out from this form solid metal. The sand mixture is contained in a system of frames or mold boxes known as a flask.

The runner system, including the sprue, feeders, and in-gates, allows the entrance of molten metal into the mold cavity. Gas and steam generated during casting exit through the permeable sand or via separate risers. After all this process we are able to pour molten metal into the mold cavity. After cooling, the sand mold is broken away, revealing the finished casting.As the metal cools, it transitions from a liquid state to a solid state. During this phase, the atoms arrange themselves into a crystalline structure. The cooling rate affects the size and distribution of these crystals. Rapid cooling (such as in water-cooled molds) results in fine-grained structures, while slower cooling (as in sand molds) leads to coarser grains.