Casting- step 1
Cover the mould in chalk. Place the mould halfway into a wooden box and fill with sand, compressing between each fill until the top of the box is reached. Flip the box over and repeat on the other side.
Casting- step 2
Take the box apart so you have two identical halves. Remove the mould.
Casting- step 3
To allow air to flow, create a small dip next to the mould shape. Cut out a cylinder in the same space on the top half. Cut out a second cylinder on the top half where you are going to pour the molten metal. Place both slides back together.
Casting- step 4
Heat in a furnace the metal until molten and remove any hydrogen by prodding it.
Casting- step 5
Pour metal in and remove any wooden supports plus the sand. Let it cool.
Casting- step 6
Use files to remove any marks made by the tools and sandpaper to smooth. Add any desired finishes.
How is investment casting different
A wax pattern is made in the shape of the required casting which is then surrounded by sand. As the molten metal is poured into the mould, the wax melts and is replaced by the metal.
Advantages of investment casting
The wax can be reused and the resultant casting requires little further work.
How is resin and plaster of Paris casting different
They use a flexible silicone or rubber mould which the liquid is poured into.
Sand casting specialist tools needed and uses
Cope and drag
Engine parts, fan blades
Sand casting advantages and disadvantages
Sand can be reused
Energy intensive
Investment casting specialist tools needed and uses
Cope and drag, casting sand, parting powder
Jewellery, complex components
Investment casting advantages and disadvantages
Little further processing needed
Energy intensive, long cooling time
Resin casting specialist tools needed and uses
Rubber or silicon mould
Jewellery, toys, small scale production
Resin casting advantages and disadvantages
Low set up cost, no cooling time, reusable mould
Castings are easily scratched, castings may not be shiny
Plaster of Paris casting specialist tools needed and uses
Rubber or silicone mould
Models, medical castings
Plaster of Paris casting advantages and disadvantages
Low set up cost, few specialist tools required, has a hard outer surface
Takes a long time to solidify, incorrect mixture can result in brittle castings
