When ordering metal, most people specify a particular size and shape of the material, and the processes employed to ensure that the raw metal meets this specification are varied and broadly flexible. Since metal is, by definition, extremely tough and therefore difficult to cut, a range of devices and measures have had to be developed, each of which is the best option for a particular type of metal or desired shape. Often, small sections of the metal will need to be removed, in order to make holes for screws, bolts and so on.
The most basic means of cutting metal are based upon manual tools, which is to say smaller cutting devices which can be operated by hand.
- The most basic of these is probably a hacksaw, a saw similar to that which would normally be used to cut through wood, but in this case constructed of steel which is strong enough for its’ sharpened teeth to work through metal.
- Chisels can also be used to take off unwanted bits of metal, either cold chisels or those, such as a ‘hardy chisel’ on an anvil, which are forced through metal when it has been heated and softened.
- Shears are scissor-like devices with blades made from carbon steel, which are capable of cutting through 18 gauge aluminium, 24 gauge mild steel and 26 gauge stainless steel.
For jobs which are too large or deal with materials which are too robust to make manual metal cutting a practical proposition, machine cutting has to be applied, and this comes in various different forms.
Turning is a process via which the sharp point of a cutting tool is applied to the metals surface as it is rapidly spun by a device such as a lathe, thus removing the top layer of metal to a pre-determined size.
Drilling, on the other hand, consist of a drill bit which is applied to the metal using a combination of force and rotation, and which therefore cuts through it. Thus, a hole of the required size will be cut right through the metal in question.
When the surface of the metal has to be smooth and of a very high quality a grinding machine may be used. A grinding machine consists of an abrasive wheel which turns while in contact with the metal, thus wearing the surface down.
Welding or Burning Technologies
Welding or burning technologies work by the application of heat to the surface of the metal, bringing it up to a temperature at which it will soften and then break along a carefully delineated line.
The first such technology to be considered is the form of laser cutting. A laser is an intensely concentrated beam of light which can be reduced to a tiny point of very high temperature and controlled in a way which means that complex and very exact shapes can be cut out of the metal. Often, the laser will be controlled by a computer which has the pattern required programmed into it. The accuracy and focus of the laser beam results in a very clean cut and a top rate finish.
Another device which operates along similar lines, using a gas flame which reaches a temperature of some 3,500 degrees centigrade, is an oxy acetylene cutter. This heats the metal up to melting point and then directs a stream of oxygen onto the spot, thus causing the metal to burn and melt along the required line.
A technique which is more contemporary than either of these is plasma cutting. A plasma torch pumps either oxygen or an inert gas out of the nozzle at high speed whilst simultaneously sending an electrical arc through the gas, thus creating plasma which is hot enough to melt the metal whilst also moving quickly enough to blow any molten metal away, thus creating a clean cut. The most up to date and lightweight plasma cutters are capable of reaching levels of accuracy similar to those achieved by laser cutting.
The remaining type of technology used to cut metal accurately is erosion technology. This is technology which mimics the effect of water upon metal in the natural environment, but does so at a highly accelerated rate. Water jet cutting is particularly useful since it doesn’t rely on the creation of heat to cut through the metal, and can therefore be used on metal which may be sensitive to the effects of heat. A water jet cutter slices through the metal using a highly concentrated jet of water or, on occasion, water with the addition of an abrasive substance.