Sand Casting Patterns

About

Green Sand Casting

The term “green sand” is known principally because of the moisture content within the sand. The sand undergoes a “mulling” process in which various clay and chemical additives that act as binders are blended with the sand, which results in a compound suitable for the sand-molding process. This prepared sand mixture is then compressed around the pattern at specific pressures and temperatures to ensure it maintains its shape throughout the remainder of the casting process. The blended sand and binders are compacted around the pattern, taking on the shape of the desired casting.

Sometimes the design of the casting entails internal passageways being formed into the mold. This is done by using sand cores, which are made of a similar sand mixture. The cores are strategically placed to form the necessary passageways in the casting. The two halves of the mold are subsequently closed, and we pour metal into the cavity where it’s left to solidify. After solidification, the sand is vibrated until it is released from the casting. The finishing process can then be completed by grinding, machining, plating, and painting.

About

No-Bake Sand Casting

In the no-bake process, we mix sand with a chemical catalyst system, which we then mold around the cope and drag halves of the tooling. After a specified period of time (depending on mold size), the sand mixture hardens to form the mold halves, and the tooling is drawn. Additionally, you may apply a refractory coating to both mold halves before they bringing them together to form one complete mold for pouring.

The pattern is removed leaving the mold cavity. Molten metal is then poured into the mold cavity. After the metal has solidified and cooled, the casting is separated from the sand mold. There is typically no mold release agent, and the mold is generally destroyed in the removal process. The finishing process can then be completed by grinding, machining, plating, and painting.

Sometimes the design of the casting entails internal passageways being formed into the mold. This is done by using sand cores, which are made of a similar sand mixture in a no-bake air core process or in a shell (hot box/blown core process). The cores are strategically placed to form the necessary passageways in the casting.

No-bake molding, like green-sand molding, is known for its versatility. Virtually all metals can be cast via no-bake molding with component weights ranging from less than a pound to several hundred thousand pounds.