Annealing
The purpose on annealing is to make your metal more pliable. When metal is worked it becomes harder and more brittle which means it my break if you overwork it, by annealing the metal it relives the stresses of the molecules, meaning that once it has been annealed it will be more malleable again and you can then work with it more. Different metals will need to be annealed more regularly than others.
Before you start the annealing process it is important to make sure any ventilation systems are switched on, and in the university building the gas proving systems must be switched on, in schools they may not have this so ensure that whatever health and safety system they have regarding gas is on and working correctly.
Dependent on the work you are doing you may wish to wear gloves, from a health and safety aspect as a teacher I think it would be a good idea to get pupils using this equipment to do so no mater what they are working on as an extra precaution, in which case it would be good to practice what you preach!
Gas taps are indicated with the colour yellow
Red = gas pipe
Blue = oxygen pipe
To anneal a piece of metal it is important to have an even heat over the material, you can help this by arranging fire-bricks around the metal to insulate the heat. When your heat bricks are set up and you have lit the touch using the ignition (light with only the gas pipe on then add the oxygen to create a fiercer flame. start heating the metal, do so evenly distribution the heat across the whole area of the material, if annealing copper heat it until it turns a dull red colour. With aluminium it is harder to tell if it is at the right temperature so a handy tip is to rub soap over the surface of the metal, when it is at the right temperature the soap will turn black. Then take your metal using tongs and quench it in cold water too rapidly cool it down. The metal can be left to cool down however to ensure no one (especially pupils) do not pick up hot metal quenching would be advisable.
Key concepts:
The following also apply when brazing and hard soldering
The purpose on annealing is to make your metal more pliable. When metal is worked it becomes harder and more brittle which means it my break if you overwork it, by annealing the metal it relives the stresses of the molecules, meaning that once it has been annealed it will be more malleable again and you can then work with it more. Different metals will need to be annealed more regularly than others.
Before you start the annealing process it is important to make sure any ventilation systems are switched on, and in the university building the gas proving systems must be switched on, in schools they may not have this so ensure that whatever health and safety system they have regarding gas is on and working correctly.
Dependent on the work you are doing you may wish to wear gloves, from a health and safety aspect as a teacher I think it would be a good idea to get pupils using this equipment to do so no mater what they are working on as an extra precaution, in which case it would be good to practice what you preach!
Gas taps are indicated with the colour yellow
Red = gas pipe
Blue = oxygen pipe
To anneal a piece of metal it is important to have an even heat over the material, you can help this by arranging fire-bricks around the metal to insulate the heat. When your heat bricks are set up and you have lit the touch using the ignition (light with only the gas pipe on then add the oxygen to create a fiercer flame. start heating the metal, do so evenly distribution the heat across the whole area of the material, if annealing copper heat it until it turns a dull red colour. With aluminium it is harder to tell if it is at the right temperature so a handy tip is to rub soap over the surface of the metal, when it is at the right temperature the soap will turn black. Then take your metal using tongs and quench it in cold water too rapidly cool it down. The metal can be left to cool down however to ensure no one (especially pupils) do not pick up hot metal quenching would be advisable.
Key concepts:
The following also apply when brazing and hard soldering
- Distribute the heat evenly no matter what metal you use
- Place your heat bricks carefully ensuring as much heat insulation
- Heat has not been evenly distributed so some parts may be pliable while others still hard, this may be more prominent when working with larger metals
- The torch may not get hot enough
- Ensure any gas proving and ventilation systems are on
- Wear gloves if necessary
- wear safety goggles
- ensure when the torch is not in use it is turned off
- never pick up hot metals with your hands always use tongs or tweezers