When we think of lasers, our minds immediately picture spacecraft firing bolts of light at one another. Perhaps for those not into science-fiction, you may instead think of light shows that use lasers. Maybe something as simple as a laser pointer comes to mind.
As you can see, lasers come in many different forms and can be used for a variety of applications. The first laser was built in 1960 and over the years has seen rapid improvements in design and application.
What exactly is a laser?
“Light Amplification by Stimulated Emission of Radiation”. That’s what the word laser stands for. Without getting too technical, lasers are simply focused beams of light that have been amplified. Light travels in waves and each colour of light have a different wavelength. The wavelength is simply the distance between each wave’s peak.
Lasers use light waves of similar wavelengths. The laser’s light waves travel together with their peaks all lined up (in-phase),thus producing a narrow beam of light that is very bright and that can be focused into a very tiny spot. Laser beams can also travel long distances as well as concentrate a lot of energy on a very small area.
Laser Cutting
As the name implies, laser cutting uses a laser beam to cut away material in a localised area. The material is either melted or vaporised by the laser beam leaving a high-quality surface finished edge. This allows complex shapes to be cut out of a piece of metal. Examples of this would be letters, numbers, logos or other designs, such as gears or parts, that are cut out of sheet metal.
Often, fibre laser cutting is also used as the first part of the fabrication process to cut out complex shapes from sheet metal that are then put through other metal processing methods like bending and joining to produce the end product. Sometimes, laser machines are used in the welding process as well.
Laser machines can also be used to engrave letters, numbers or shapes on a piece of metal or wood. This is done by just cutting away the surface to a shallow depth rather than laser cutting completely through the material. Laser engraving is often used to engrave or etch barcodes, QR codes and serial numbers onto parts for industrial use. There is also a growing demand for using fibre lasers to remove rust, paint and other surface-level contaminants from sheet metal.
As laser cutting is a highly precise technique, it uses CNC (Computer Numerical Control) machines to control the movement or cutting path of the laser beam. This allows a high level of control and flexibility in producing any design. Often, these CNC machines are linked to CAD/CAM (Computer Aided Design/Computer Aided Manufacturing) systems. The integration of the laser machines to CAD/CAM can be done either online or offline and allows for the direct generation of the product from the design.
Machine Configurations
When using laser cutting to cut metal, there are generally three different forms of machine configurations available. The configuration refers to the way that the laser beam is moved over the material to be cut or processed. In general, movement over a piece of sheet metal is left and right, forward and backward and sometimes, vertically up and down if the laser head has 3D movement capability.
- Fixed optics
In this configuration, the laser remains stationary while the sheet metal or workpiece is placed on a movable table. The table moves left and right or forward and backwards while the laser cuts into the metal. One issue that arises with this configuration is that the weight of the workpiece may cause an issue.
This is because a heavier workpiece would mean that the weight of the table increases and affects how smoothly and quickly the table can move. This then affects the cutting precision of the laser as it may not cut as cleanly into the sheet metal as the table does not move fast enough. A fixed optics system is thus ideally suited for lighter sheet metal.
- Fixed material
This configuration is the most popular. In this setup, the sheet metal or workpiece is stationary while the laser is manipulated to move left and right and forward and backwards. This system offers easier prediction and control of the movement as only the laser head moves.
This system overcomes the limitation of the weight of the sheet metal or workpiece. However, because the laser head moves there may be issues with slight variations in the laser beam size as the head moves across the sheet metal resulting in slight variations in cutting tolerance.
- Hybrid System
The hybrid system combines the advantages of both flying optics and fixed optics systems. In a hybrid system, the laser beam moves along one axis while the workpiece table moves along the other. If the laser beam moves forward and backwards, the table will move left and right.
Similarly, if the laser beam moves left and right, then the table will move backwards and forward. This results in a more consistent laser beam delivery path. The downside to this system is that it has a more complex setup process and sometimes there are coordination errors between the two moving components thus requiring move maintenance and calibration.
Some more advanced machines integrate all the different movements to allow 3-Dimensional cutting for workpieces. 3-Dimensional cutting allows even more complex shapes to be generated and can produce angular designs as well.
Types Of Laser Cutting
In sheet metal laser cutting today, two types of lasers are commonly used – CO2 (carbon dioxide) lasers and fibre lasers.
Each of these lasers uses a different base material to generate light. In the case of CO2 lasers, a sealed glass tube is filled with Carbon Dioxide. A high voltage is introduced into the tube that reacts with the CO2 gas and produces light. Fibre lasers use physical light emitting diodes to generate light.
These different lasers have varied uses in terms of handling different types of material and thicknesses as well as differing precisions in cutting.
However, in recent years, laser cutting of sheet metals has been dominated by fibre lasers. The main reasons include process reliability. Fibre Laser cutting also produces higher cutting speeds as well as the ability to cut reflective metals such as copper and brass. There is much less maintenance required thus resulting in a lower cost of ownership and these savings can be passed back to the customer.
Conversely, CO2 lasers, have shown a smoother cut edge for some thicker materials (typically those thicker than 6 mm). However, this advantage is slowly diminishing as fibre lasers are making more and more advances in technology as time goes by.
That is why we focus on Fibre Laser cutting at NS Metal Fabrication Specialist.
Fibre Laser Cutting – how it works
As mentioned previously, lasers are based on light amplification, so the first step is to have a light source. The light source used in fibre lasers is created by several lights emitting diodes (LEDs). This initial light source is known as the seed laser. Once the initial light source is generated, it is focused, amplified and then channelled into a fibre optic cable. These fibre optic cables are very similar to that used for data transfer. Those of you that have high-speed fibre internet at home or in the office would know what a fibre optic cable looks like.
Fibre lasers can produce an extremely narrow laser beam and as a result, their intensity is up to 100 times higher than that of CO2 lasers with the same average power input. Both the narrow beam and high-intensity laser beam makes it extremely viable for cutting reflective metal material. This is one of the main advantages of fibre lasers compared to CO2. Fibre laser machines also have a long service life compared to CO2 laser machines. They are also smaller and consume less power than CO2 lasers, resulting in cost savings that can ultimately be passed on to the consumer.
Fibre lasers can be used as a continuous beam or in pulsed settings. This allows different functionalities. Continuous cutting is used to cut out patterns and shapes while pulsed cutting is used to cut holes or slots. For complex shapes or designs, a combination of continuous cutting and pulse cutting is used.
Need more information?
Fibre laser cutting is used extensively at NS Metal Fabrication Specialist and we have a wide variety of machines that we use. With over 30 years of experience, our company offers a highly personalised approach to the customisation and supply of high-quality metal and steel, especially in regard to using laser cutting for complex shapes and designs.
Contact us today to discuss your sheet metal fabrication needs or simply to get further information on how we can work together.
