Metal is a popular material to use in schools within Design and Technology lessons as it is generally not too expensive in comparison with other materials that are available.
There are many different tools for marking out on metal:
A hacksaw is normally used to cut metal by hand. If a smaller piece of metal is being cut, then a junior hacksaw can be used. Once the metal is cut close to a marked line, a file can be used to remove material up to the desired line. Files can be bought in different shapes, sizes and cutting grades - a rough-cut file can remove metal faster than a smooth-cut file and should always be used first.
Once filing has been done and the profile of the metal is at the desired shape, the file marks can be removed with abrasive papers such as emery cloth and silicon carbide paper (often called ‘wet and dry’ paper as it can be used both wet and dry). A buffing machine can be used to polish the metal to achieve a mirror-like finish.
Metal can also be drilled by using a variety of different drill bits, which work by twisting into a piece of metal:
There are many different joining methods for fixing metal in place. Non-permanent methods include nuts and bolts, screws and rivets. Whilst many would consider a rivet a permanent method of joining, it is possible to drill out an old rivet so that a new one can be used.
Permanent methods of joining metals are listed in the table below:
|Soft soldering||Used to solder printed circuit boards (PCBs) and electronic components. Plumbing application where copper pipes are joined together.|
|Brazing||Used for joining steel by melting a brass rod on the hot steel. As the brass melts, it forms a joint. Brazing is a slow and safe way to learn about joining metal with heat.|
|Gas welding/Oxyacetylene welding||Oxygen and acetylene are used to produce a flame with a temperature of over 3,000°C. A filler rod is melted so that pieces of metal can be joined together. Gas welding/Oxyacetylene welding is faster than brazing and can also be used to cut metal.|
|Arc welding||Heat is produced by a high current that is passed down the filler rod. When the filler rod melts, it fuses the pieces of metal together. Arc welding is fast and portable.|