Split pattern or two piece pattern

This is the most widely used type of pattern for intricate castings. When the contour of the casting make sits withdrawal from the mould difficult, or when the depth of the casting is too high, then the pattern is split into two parts so that one part is in the drag and the other in the cope. The split surface of the pattern is same as the parting plane of the mould. It is shown in the figure

Figure- Split Pattern

The two halves of the pattern should be aligned properly by making use of the dowel pins which are fitted to the cope half. These dowel pins match with the precisely made holes in the drag half of the pattern and thus align the two halves properly as seen in Figure.