Casting Metals

Learning Objectives

• Pupils see how the addition of heat energy to a solid produces a liquid.
• Pupils see how the process is reversible
• Pupils see how this property is used to manufacture artefacts
• Pupils develop a range of manufacturing skills   

Content

• Pupils see how substances exists in one of three states of matter, (possibly four if
• plasma is included) and how substances move from one state to another depending
• on the energy their molecules possess.
• Pupils then see how this physical property can be used to our advantage when casting metal.
• Pupils then produce a mould which they use to cast pewter.  

Resources

• Pewter or white metal alloy (TEP resources)
• Brazing hearth or method of melting the metal
• Pewter casting ladle
• 3mm MDF, cut into rectangles, approx 60mmx100mm
• 12mm MDF, approx 60mmx100mm
• Round Surform
• Reciprocating saw or coping saws
• Vice or clamp
• Gloves
• Goggles
• Access to a computer running Microsoft PowerPoint.

Procedure

• Pupils are show the Powerpoint that explains how a materials state depends on the energy it contains.
• Pupils see how to make a MDF mould that can be used for pewter casting
• Pupils see the size of the 3mm MDF blanks and design a motif to suit, they include a pouring spout and a runner for the metal.
• Pupils cut the shape using a reciprocating saw or coping saw
• Pupils then use the round Surform to produce a recess to match the shape of the spout in the thicker outer MDF pieces.
• Pupils clamp the MDF pieces together.
• Staff and pupils melt the pewter and pour into the mould
• The casting is left to cool.
• The casting is trimmed, filed and drilled as required.  

Safety Issues.

• The reciprocating saw needs appropriate guards which are positioned correctly when in use.
• Goggles are required and pupils need to be shown how to use the equipment.
• When casting the demeanour of the pupils should be considered and the decision as to whether they pour the metal made accordingly.
• Pupils should wear gloves and goggles, have no exposed flesh and pour the metal in an area not accessible to other pupils.
• Staff should be in close attendance at all times. Pupils love casting because of the element of danger it entails and is safe if the above guidelines are followed. Staff should make the final decision as to whether a child pours the metal and based upon the specific situation.
• The casting will remain hot for approximately ten minutes and pupils must be told not to touch the casting until instructed to do so.
• Pupils should stay with the casting and given the responsibility of telling others not to touch it

Estimated Time To Complete The Exercise – two hours.