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FOUNDRY WORK (3)

V. Ryan © 2003 - 2009

 

Sprue pins are positioned. One usually on the back of the pattern and the other to the side. These will eventually provide an entrance and exit for the molten aluminium when it is poured into the sand.
The sand is packed/rammed into the cope in the same way as the drag. Parting powder is first applied, followed by facing sand. The sprue pins should be taller than the box and stand out from the sand when it is levelled with a strickling bar.

Small depressions are dug into the sand at the top of the two sprue pins. These are useful when the aluminium is poured. The depressions are called the pouring basin and feeder.

 

   

The top box (the cope) is then removed and if all is well the cope with the sand inside should lift off the drag (bottom box) without the sand falling out. A small ‘gate’ is cut below the position of one of the sprue pins. This will help the molten aluminium flow into the cavity left by the mould. Small tools are available or can easily be made to dig a variety of shapes in the casting sand. They are similar to small trowels.

   

   

 

   

The pattern is removed using a ‘spike’. The end of the spike can be threaded and so it can be screwed into the softwood pattern. Before removing the pattern it is a good idea to gently tap the spike so that it loosens the pattern from the sand. It can then be lifted away from the casting box (drag).

   
 
   

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