The Right Pattern for Your Needs
In addition to mocking up new or altered patterns, another important remit of patternmaking includes the refurbishing of models in use. This encompasses the minor and minimal repair of patterns, sprue and riser systems which are continually necessary; adding supplementary valves; changing out blocked lines; and all sorts of other minor adjustments and reconditioning from normal wear-and-tear.
Not least can this also include predictions, based on years of experience, of whether the mould itself will hold, or whether part of it may crack and break, and eventually become stuck in the casting – the so-called “breaking of cods”.
This phenomenon can occur when the sand is compressed around the pattern in the flask/moulding box; in the patterns, there are frequently impressions, indentations, or spaces between the moulding box and the pattern. Loose green sand is compressed into these indentations, resulting in bits of the sand mould that “stick out” into the hollow space – the so-called “cods”.