What is Laser Cutting?
Our laser cutting machines can produce complex exterior contours, accurately and cost-efficiently. The laser beam is typically 0.15 mm (0.006 in) diameter at the cutting surface with a power of 1000 to 2000 watts.
Laser cutting can be used alongside the CNC/Turret process. We find that whereas CNC/Turret is ideal for producing internal features such as holes, laser cutting produces external complex features with ease. Laser cutting can also take drawings direct from CAD software to produce highly complex flat form parts.
Laser cutting works best on materials such as carbon steel or stainless steels. Metals like aluminium and copper alloys that are more difficult to cut (due to their ability to reflect and absorb and conduct heat) require more powerful lasers.
- The minimum radius for slot corners is 0.75 mm (0.030 in). Unlike blanking, piercing and forming, normal design rules regarding minimum wall thicknesses and hole size (as a per cent of stock thickness) do not apply. Minimum hole sizes can be as low as 20% of stock thickness, with a minimum of 0.25 mm (0.010 in) for up to 1.9 mm (0.075 in). Contrast this with normal piercing operations with a recommended hole size of 1.2 times the stock thickness.
- Burrs are quite small compared to blanking and shearing. They can be virtually eliminated when lasers are used and eliminate the need for secondary deburring operations.
- As in blanking and piercing, considerable savings can be made by nesting parts and cutting along common lines using state-of-the-art CAD software.
How does laser cutting work?
Laser cutting works by melting, burning or vaporising the material. An assist gas is then used to clear the cut zone of any molten or burnt material, or gas vapour.
In the past, laser cutting was highly complex and was generally carried out manually. Today it still requires considerable skill. But thanks to our state-of-the-art technology, the result is superior, efficient and cost-effective.
These days, many common parameters are pre-programmed into the machines, allowing much easier setting. The process isn’t completely automated. Skilled operators are employed to ensure that the cut quality is consistent and the end result precision-perfect.
The material is pre-pierced outside the cutting area. Heat is then applied via a laser beam. Finally an assist gas is used to remove the heated material and produce the cut.
Which gas is used depends on the material to be laser cut, and it’s vital to make the right choice. Most commonly used gases are oxygen (mainly carbon steels), nitrogen (non-ferrous steels & non-metals) and argon (more exotic materials like titanium). St Ann’s Sheet Metal can also use compressed air to cut most materials 2mm thick or under.
Industrial laser cutting machines are predominantly used to cut parts from flat-sheet material. Some machines are specially adapted to cut tubular components while multi-axis lasers cut pre-formed components.
Limitations of laser cutting for sheet metal
The cut-edge quality depends on the type and thickness of material: the thicker the material, the more prominent the striations on the cut-edge (the lines where molten zone meets cool zone).
These striations affect the tolerance achievable. For example, in 2mm mild steel we would offer +/-0.1mm accuracy. In 10mm steel the repeatable tolerance would increase to +/-0.2mm, and at 20mm we would be maintaining +/-0.4mm.
The above chart shows the maximum thickness we’re able to cut, the amount of detail achievable (depending on thickness and material) and the type of material. All cutting is done inside the machine, so operators are never exposed to the lasers directly. Please note that we’re unable to cut materials like plastics due to health & safety issues.
A laser is made up of photons. This means that part of its energy can be reflected away by materials like aluminium and copper alloys which, as thermal conductors, also distribute the heat more evenly.
Carbon alloy and stainless steel are poor heat absorbers. Heat is therefore concentrated into the laser’s path more readily, making these metals popular workpiece materials for laser cutting.
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