Workshop Technology
Riddle is used for

Moistening the sand around the edge before removing pattern
Reinforcement of sand in the top part of moulding box
Smoothing and cleaning out depressions in the mould
Cleaning the moulding sand

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Workshop Technology
The purpose of a riser is to

Feed the molten metal to the casting in order to compensate for the shrinkage
Act as a reservoir for the molten metal
Deliver the molten metal from pouring basin to gate
Deliver molten metal into the mould cavity

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