The process of laser cutting involves slicing various kinds of materials. These are crucial in many manufacturing and industrial applications, and it’s used in many workshops, businesses, and engineering fields. Get an overview of this process when you click here.
Some of the cutting techniques use a direct output of laser power with the help of optics. Commonly, CNC or computer numerical control and laser optics are utilized to direct the beams into the material that needs cutting. The process uses a motion control guided by the G-code or CNC to follow the patterns designed explicitly for prototypes.
With a focused laser beam that’s directed to the material, the result is that a block of metal can be burned, melted, vaporized, or even blown away by jets of gas. This leaves an edge to a finish of a high-quality surface and the process is considered to be faster.
A Bit of History in this Technique
It was the year 1965 when the first production of cutting machines that utilized lasers was produced. They were used mainly in diamond mines, specifically in the drill holes. Western Electric Engineering Research first made these machines for industrial purposes.
In 1967, it was Britain that pioneered the oxygen jet cutting techniques that were laser-assisted. The technology was to help with the further production of titanium for aerospace. At this same time, the carbon dioxide lasers were adapted in textiles and other non-metals because they don’t have much power to overcome the thermal conductivity that’s usually found in metals.
The Processes Involved
The generation of the beams involved the stimulation of electrical discharges and lasing materials in a contained space. As the lasing material continues to receive stimulation, the rays reflect each other internally with a mirror’s help. This continues until there’s more than sufficient energy for the light to escape the enclosed space. It goes out and becomes a monochromatic coherent kind of light.
Fiber optics or mirrors direct the light to a coherent lens. This lens focuses the lights on the block of metal, and the narrowest part is usually about 0.32 mm in diameter. Determine the thickness of the block of metal that needs cutting; the kerf’s width may be as small as 0.10 mm as possible for more penetration.
For the cutting to start, it should begin on the very edge of the material. The piercing should be done initially, and this involves highly-powered pulsed laser beams that make a small hole. This can take around 15 seconds on a 13 mm slab of stainless steel.
One of the advantages of using lasers instead of mechanical cutting techniques is that it significantly reduces the contamination in the workspace, and the workload and human intervention decreases. There is no cutting edge that a material can contaminate. Precision from an Aeon laser is achieved in no time because the beams are not wearing during the entire process. This reduces the warps as well.
Lasers also have an advantage over plasma because they are more precise. They use less energy during the process, especially when metal sheets are involved. Also, some materials are more difficult or even impossible to shape when done manually or by traditional means. But there’s an advantage with plasma because it can penetrate thicker metals that not many industrial lasers can’t graze.
Types to Know
Usually, you can find three main types of laser technology available. The CO2 laser is used for engraving, boring, and cutting. The neodymium and yttrium-aluminum-garnet are similar in styles, but they are used in different applications. Neodymium is used for boring holes where they don’t need many repetitions, but higher energy is involved. The yttrium-aluminum-garnet laser is usually used for engraving and boring. All of these varieties are used for welding as well.
The CO2 varieties are usually pumped up through the process of gas mixing or radiofrequency energies. This RF or radiofrequency method is newer, but it’s becoming a popular one in many operations. The DC-excited or gas mix technique may require more electrodes inside the cavities, and this can cause erosion in optics and glassware materials. The resonators don’t have external electrodes, and many operators don’t usually encounter erosion problems with them.
CO2 lasers are usually used with a lot of materials. They include the following:
- aluminum
- wax
- fabrics
- paper
- engineered wood
- wood
- plastic
- mild steel
- titanium
The YAG or yttrium-aluminum-garnet technology is used for the following:
- ceramics
- scribing metals
Aside from the power source, the gas flow can affect the laser’s performance as well. Some of the common variants of CO2 machines include slab, transverse flow, slow axial flow, and fast axial flow. In fast axial flow resonators, a mix of nitrogen, helium, and carbon dioxide is circulated by a blower or a turbine. Transverse flows circulate at lower velocities and a gas mix, and they require simple blowers.
Diffusion or slab-cooled resonators have more strategic gas fields that don’t require any glassware or pressure. This can lead to savings as many operators don’t have to replace glassware or turbines from time to time.
The external optics and laser generators, including the lens, may require cooling. This cooling process is different, and the factors that can affect them can be the configuration and the size of the system. Waste heat is transferred to several coolants, or they are cooled directly to the air. Water is usually used as a medium for the coolant, and it’s generally going into a heat transfer system or a chiller.
Laser microjets are water-guided types that have pulsed beams. They are coupled with low-pressure that’s in the form of water jets. They are used to perform various functions like optical fibers, internal reflection, and laser beams. One of the advantages of a microjet is that the water will also remove the debris and cool the materials simultaneously. Other additional benefits of these techniques include parallel kerfs, higher dicing speeds, and omnidirectional cuts.
You may also want to consider fiber lasers that are a rapidly growing tool in the industry. This doesn’t work like CO2 because this utilizes a solid medium instead of gas or liquid. The technology behind fiber is a seed laser. This “seed” is amplified through a glass fiber with a wavelength of 1064 nm. This is an ideal tool for cutting reflective metal materials. Fiber technology has the following benefits:
- More excellent performance and greater reliability
- Rapid times of processing
- Minimal maintenance required
- Higher productivity
- Reduced consumption of energy bills
- No optics that’s needed to be aligned or adjusted
- No need for replacement lamps
Methods Involved
There are various methods involved when it comes to laser-cutting technology. Some of them are melt, blow, vaporization, cold cutting, scribing, thermal stress, cracking, and burning.
Vaporization Cutting
This is a process that focuses on the heat of the beams to generate a keyhole. Keyholes can result in a sudden increase of absorption, and they can quickly deepen the hole created. As the hole is deepened, the material will reach a boiling point where the vapor erodes the material. This is a method commonly used in carbon wood and thermoset plastics that don’t melt.
Melt and Blow
The fusion cutting of melt and blow uses high-pressure gases to ensure that the molten area is blown, thereby decreasing the energy requirement. The material is first heated until it reaches a boiling point then jets of gases are used to blow the molten block out of the kerf. This is necessary to avoid an increase in temperature. They are usually used in many kinds of metals.
Thermal Stress Cracking
This utilizes brittle materials because they are known to be extra reactive to thermal fracture. This is why this feature is often exploited by the operators in thermal stress cracking. The beam is mainly focused on thermal expansion and on the surface to localize the heat.
As a result, the block can crack, and it can be a guide when the lasers move throughout the material. The cracks are moved in order of m/s, and this the technology for cutting different kinds of glasses. You can learn more research about thermal stress here: https://www.researchgate.net/publication/236855831_Thermal_Stress_Cracking_in_Granite.
Stealth Dicing
Stealth dicing usually separates silicon wafers from semiconductor device fabrication, and this is often pulsed with a YAG laser. The wavelength is about 1064 nm, and a gap of silicon can adapt it. The dicing process involves breaking and scribing as well as laser cutting to ensure accuracy and precision. The silicon chips involved are incorporated into carriers that are suitable for building a computer and other electronic devices.
Reactive Cutting
Reactive cutting involves flame cutting and burning stabilized laser gas cutting. This is similar to an oxygen torch cutting method, but the laser beam is the ignition source. This is mostly used for a one mm-thick carbon steel slab. This is ideal for cutting steel plates that are very thick because it just uses low laser energy. There are others aside from these, but these are the popular ones more commonly used out there.
