(i) Solid (or) single piece pattern:
Patterns are made in one piece without joints, partings (or) loose pieces is known as "Single piece pattern" and these are suitable only for very simple castings. There is no provision for Runners and Risers etc., Moulding can be done either in the foundry floor (Called Pit Moulding) or in a Moulding Box. There is no difficulty in withdrawing the pattern from the mould as the broadest portion of the pattern is at the top. As an example, if a cylindrical pin with a circular head has to be cast, a one piece pattern shown in Fig., will be adequate.
(ii) Split pattern
It is not practical to have one piece
It is not practical to have one piece pattern for parts of complicated shapes, because it would not be possible to withdraw the pattern from the mould. For example, if a circular head was added to the bottom of the pin shown in Fig. 6.1, it would make it necessary to go in for a split pattern as shown in Fig. 6.2.
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