
Pattern Definition
The pattern is a replica of the final product, minus any necessary machining or surface finishing needed prior to assembly of the final product. A sand cast foundry creates a pattern or mold from wood, aluminum, steel, or other materials to make a shape that will eventually make an impression in the sand. The pattern makes its impression in the sand, the molding machine adds pressure to the sand squeezing the sand around the pattern. The pattern is vibrated loose from the now hard sand, leaving the desired shape in the sand. This impression is subsequently filled with molten aluminum. And when the aluminum is solidified, the casting is shaken out of the mold.
Types of foundry Patterns
There are different kinds of foundry patterns depending on the complexity of the final casting and the casting method. Common types include:


Pattern Allowances in Casting
Patterns are not exact replicas of the final product but incorporate certain allowances:
Cores & Core Boxes for Internal Features
For castings that require internal cavities or hollow sections, cores or core boxes are used alongside the main pattern. Cores are placed inside the mold cavity to block out specific areas where metal should not flow, creating hollow sections within the final casting. Core patterns are carefully designed to match the overall casting dimensions and ensure that internal shapes are as precise as external ones.
