• The pattern is used to form the cavity in the sand mold. The cavity is shaped to the desired contours and dimensions of the final casting.
• The pattern is positioned in the the open frame (flask) and sand is packed around the pattern. The pattern/tool is then removed, leaving the casting cavity in the sand mold.

Patterns are commonly machined to the desired shape in wood, plastic, or metal. The cost of machining the pattern depends on the hardness of the pattern material. Softer materials are less expensive to machine.

• Sharp contours are more susceptible to wear than flat or curved contours on the pattern.
• This is a particular issue for automated molding machines in which the sand is mechanically rammed in the molding operations.

The durability of the pattern depends on the hardness of the pattern material. Harder materials are more durable and have longer life, but they are also more expensive to manufacture.

Choose a pattern material --       WOOD,     PLASTIC,       METAL     -- based on your estimate of machining costs and pattern life.

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