Sprue Pins are used to create the runner and riser in the sand mould
Sprue pins are set a distance from the pattern to allow sufficient space to cut gates into the mould. The pattern and sprue pins are coated with parting powder prior to covering with sand and ramming firm. The pattern and sprues are rapped prior to removal.
It is important that the sand is not layered by compacting into separate stratas with the butt of the rammer. If so these sand layers can seperate causing the mould to fall out.
Good quality wooden sprue pins are always made from hardwood with a coating of linseed oil to prevent water absorption. They come in various length and diameters to suit the size of the casting, feeding requirements and moulding box size. They have a draught/taper which allows easy removal from the mould.
Some founders prefer to use a sprue cutter and cut the runner and riser after the mould is rammed up
