The term LASER is an acronym for “light amplification by stimulated emission of radiation.”
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When a laser is used, light is intensely focused onto an object at a particular point. This focused light (referred to as ‘spatially coherent’ light) causes an extreme elevation in the temperature of the illuminated area. The material under the illuminated area melts rapidly or is vaporized, and a cut or fissure forms in the material.
Fig.1: Laser Cut Parts
The basic idea behind laser cutting is simple. Carrying out laser cutting in practice, however, relies heavily on the use of advanced equipment, technology and expertise in cutting methods. To get the best results at a manufacturing level, a good deal of expertise and care are needed when methods and technologies are chosen.
In this guide, we’ll explain what the most common modern laser technologies and processes are, where they’re best applied and how laser cutting compares to other cutting technologies.
A wide variety of materials can be formed or processed through laser cutting. The most frequently laser cut materials are common metals like mild steels, stainless steels, steel alloys and aluminum. A wide range of other metals can also be cut. As well as metals, other materials, like wood, plastics and ceramics, can all be cut with lasers.
Laser cutting technology has evolved considerably within the last twenty years or so. Nowadays, the engineer has a very wide choice of lasers, machining principles and computerized controls. Lasers can now be used to cut materials to a level of accuracy that wasn’t possible in the not-too-distant past.
For industrial fabrication, the two laser types most commonly used in metal cutting and manufacturing are stimulated gas emission CO₂ lasers and fiber lasers.
Stimulated Gas Emission CO₂ Lasers
The carbon dioxide gas emission laser was one of the earliest lasers invented. Despite the age of the technology, these lasers are still one of the highest power continuous wave lasers available. They’re still frequently used in manufacturing today, and they make a good choice in a lot of applications. As we’ll discuss, assistive gases can be used to adapt the way these lasers work.
Fig. 2: Functional Parts of a CO2 Laser Diagram
From the above diagram, it can be seen quite clearly how the functional parts of a CO₂ laser fit together. Mirrors reflect light into a high intensity monochromatic stream of light photons that exit the laser at the wavelength shown. Water is used to cool the gas tube during stimulated emission. Various gases, such as CO₂, N2 and helium, can be used during the process.
Fig. 3: Rotational-Vibrational Energy in CO2 Laser Stimulated Emission
From the diagram above, it can be seen that within the vibrational energy levels of CO₂, there are rotational sub-energy levels. A mixture of N2 and CO₂ is introduced into the gas cylinder, and the N2 atoms are excited through an electrical pumping system. The excited N2 atoms begin colliding with the CO₂ atoms, and an energy transfer takes place. This causes the CO₂ atoms to enter a higher vibrational energy level.
At this higher vibrational energy level, spontaneous emission occurs, and the CO₂ atoms reduce in vibrational-rotational energy. They then give off some of their energy, which increases the energy and intensity of the incident light.
CO₂ Laser Cutter Benefits Include:
Stimulated Gas Emission Laser Cutting Processes
With stimulated gas emission CO₂ lasers, there are two laser cutting processes that are commonly used: Fusion cutting and oxidative cutting. These are based on the use of assistive gases during the cutting process.
Fig. 4: Typical Oxidative Laser Cutting of Sheet Metal
Oxidative Laser Cutting with Oxygen as an Assistive Gas
Oxygen is the standard active assistive gas used for laser cutting mild and high carbon steels with CO₂ lasers.
When cutting with oxygen, the chemical reactivity of oxygen at the elevated temperatures under the laser causes the material to be burned with an accelerated action. The burned material is sometimes vaporized if the induced temperature in the vicinity of the laser cut is high enough. The liquid iron oxide of low viscosity is removed from the kerf by the sheer force of the oxygen jet directed into the kerf.
The pressure of the oxygen jet determines the rate of removal of the melt shear from the kerf. The value of the maximum oxygen pressure will be determined by the thickness of the material that will be cut. Oxygen purity is important for quality cutting.
Laser Cutting with Nitrogen as an Assistive Gas
Cutting with non-reactive gases, such as nitrogen, is often referred to as clean cutting or high-pressure cutting. In this case, the material is melted solely by the laser power and blown out of the cut kerf by the kinetic energy of the gas jet.
With nitrogen assisted laser cutting, the melt-shear removal process is the only active process as inert gases do not react with the molten metal to create additional heat. Therefore, much higher laser power and gas pressures are required. This is because molten steel has quite a high viscosity compared with the liquid iron oxide generated during cutting with oxygen.
Laser cutting with nitrogen would be a typical choice for cutting some stainless steels (to avoid part oxidation) as well as aluminum and some of its alloys.
With recent advances in technology and capabilities, fiber lasers are rapidly becoming the laser of choice for industrial cutting applications. A fiber laser is a type of solid-state laser where monochromatic and pumped, intensified light is directed and wave-guided down an optical fiber towards the cutting surface. The light is not passed through any gas for stimulated emission (i.e. a “solid gain medium”).
Fig. 5: Active Components and Beam Propagation in a Fiber Laser
The diagrammatic view below, shows the basic configuration of the optical circuit of a high-power fiber laser. The optical circuit consists of three major sections: The pump section, the oscillator section and the beam delivery section. In the pump section, laser light from pumping laser diodes (LDs) passes through optical fibers into a pump combiner. The pump combiner couples the pump light from the multiple LDs into a single-mode optical fiber.
In the oscillator section, the pump light from the pump combiner propagates through a double-clad fiber (active fiber), as depicted in Fig. 6. The pump light excites the Yb ions and is amplified by the FBGs (Fiber Bragg Gratings). The FBGs act as mirrors with high and low reflectivity. The laser light is emitted from the low-reflectivity FBG. The beam delivery section is composed of an optical fiber that passes the laser light from the oscillator section to a processing head or beam coupler.
Fig. 6: Working Mechanism of a Fiber Laser
Generally, when laser cutting metals with fiber lasers, the upper limit on thickness of metal sheet that can be cut is around 20 – 25 mm for mild steels. Above this thickness, higher power CO₂ lasers are used. However, with specialized fiber lasers that are available for a higher price, it is possible to cut plates thicker than this. Fiber lasers are now the tool of choice for cutting metal below 15mm thickness.
Fig. 7: High Power Fiber Laser Cutting Thick High Carbon Steel Plate
One of the big general benefits of laser cutting is that lasers can be used to cut a wide variety of materials. It is necessary to select the right laser and cutting process for each material. However, lasers can be used on more materials than people sometimes expect.
Here are the materials most often cut with laser cutters:
Metals
Lasers are particularly useful for cutting metals. Not only can lasers cut most metals, but they also create accurate, clean cuts in metal. On top of this, lasers can cut metals quickly and at a relatively low cost. Lasers can also be used to cut both thin and thick metals, with high power CO₂ lasers being used for the thickest metals.
Metals that are commonly cut with lasers are:
The biggest challenge when it comes to laser cutting metals is cutting highly reflective metals. Brass and copper can be challenging to cut, although fiber lasers tend to be effective. Other highly reflective and difficult to cut metals are gold, copper, silver and bronze.
Plastics
CO₂ lasers can be used to cut plastics, although only certain types of plastic can be cut with lasers. Fiber lasers can be used to mark plastic parts, but cutting is not recommended. The working environment also needs careful consideration because many plastics may produce toxic fumes when laser cut.
Wood
It is possible to cut wood with a laser, although attention needs to be paid to flammable resins. Plywood and MDF are two common types of wood that are suitable for laser cutting.
Paper and Cardboard
Paper and cardboard can both be cut with a laser.
It’s possible to get very good results when laser cutting these materials, with intricate patterns achievable. Decorative, pop-out cards are an example of a cardboard laser cutting application. Moderate power levels and fast speeds should be used for cardboard, and low power levels and fast speeds should be used for paper. Ventilation is required because toxic fumes may be produced.
Leather
Leather can be laser cut. CO₂ lasers are most often used, with cutting through multiple passes often being a good method. Clean cuts are possible when laser cutting leather, and it’s possible to avoid problems associated with other cutting methods.
Ceramics
Ceramics are ideal for laser cutting because they have good thermal insulation properties. Ceramics cut with a clean edge under a laser and little discoloration usually takes place. Most commonly, CO₂ lasers are used, with careful selection of lasers and processes necessary. Laser engraving is also common with ceramics, with lasers being used to create a shallow engraved texture.
Some types of ceramic that are laser cut are alumina, porcelain, zirconia, earthenware, silicon carbide, aluminum nitride and ceramic tiles.
Here are some materials that can’t be cut with a laser.
Some Plastics
While some plastics can be laser cut, others can’t. Most of the materials that can’t be laser cut are plastics. Here are some common plastics that it isn’t possible to cut with a laser:
Fiberglass
Fiberglass consists of glass and epoxy resin, which are materials that both perform poorly when laser cut. Glass is highly reflective and difficult to laser cut, while epoxy resin creates a large number of toxic fumes. Those fumes include hydrogen cyanide, H2, CO, CH4, C2H6, C2H4, C3H6 and C3H8, ethane, ethylene, propylene and propane.
Another material that can’t be cut because of the presence of epoxy resin is coated carbon fiber. This is carbon fiber that’s been pre-impregnated with epoxy resin so it can be thermally bonded in a hot press.
Polystyrene and Polypropylene Foam
These materials are generally regarded as being too flammable to be laser cut. They are often burn or become misshaped at the cutting edge. Discoloration also occurs.
However, it should be pointed out that nowadays these foams are actually cut with lasers more often. While the high flammability does often rule out laser cutting, with the right lasers and methods, some manufacturing facilities are able to laser cut these materials. Thinner sections of polystyrene and polypropylene foam are more suitable for cutting.
Laser cutting offers many advantages over other cutting technologies such as mechanical die punching, saw cutting, plasma cutting, waterjet cutting and stamping.
Some of the key advantages are listed below:
Repeatability
Laser cutting machines are CNC controlled, and they’re generally operated using complex software to optimize part path, machine speed and sheet metal utilization. This means they produce complex, precision parts in a repeatable and efficient manner. Part variability between production runs is minimal, especially when using a fiber laser machine due to much lower levels of required maintenance.
Finishing
Laser cutting produces generally high-quality cuts and edges for thinner parts, which means costly secondary finishing or cleaning usually isn’t required.
Post-cutting tooling often isn’t required as well, as it often is with other processes like stamping. As well as the cost and time associated with the tooling process, tools don’t need to be maintained or checked for deviation as much.
A reduced amount of contamination of workpiece cutting edges also occurs.
Fig. 8: Laser Cut Parts With Surface Finishing
Higher Precision and More Design Possibilities
Certain part geometries or designs are also possible via laser cutting that could not be made by other methods. Precision is generally better due to less wear and fewer moving parts involved in the cutting process.
Better Sheet Utilization
Fiber lasers in particular have a very focused beam, which reduces kerf width and the amount of material used. Combined with the lower levels of mechanical distortion involved in the cutting process, tighter tolerances, and less material distortion, this means parts can be nested extremely close together on sheet metal being processed by laser cutting. This translates to higher material utilization and lower part cost.
Advantages Laser Cutting Mechanical Cutting Waterjet Cutting Plasma Cutting Precision/Tolerances ✓ Intricate Design Capabilities ✓ No Mechanical Distortion ✓ Material Costs (Less Waste) ✓ Maintenance Costs ✓ ✓ Quick Prototyping/Design Adjustments ✓ ✓ Composite/Multi-layer Material ✓ Thick Materials ✓ ✓ ✓ ✓ No Thermal Distortion ✓ ✓ Operational Costs ✓ ✓ Range of Suitable Materials ✓ ✓ Turnaround ✓ ✓ ✓Table 2: Comparison of Various Cutting Processes
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Laser cutting makes a great choice in a number of different manufacturing scenarios. The main benefits it brings are speed and accuracy, but there are other upsides as well.
Below are the situations in which it could well be a good idea to employ laser cutting.
When a High Level of Precision is Needed
It’s possible to achieve the highest levels of precision with laser cutting. Laser cutters are highly accurate, and they produce very narrow kerf widths. Kerf widths as small as 0.1mm are possible with laser cutters. With computerized controls, very accurate cuts can be made, and the possibility of human error is removed from the equation.
Laser cutting is particularly good for delicate and complicated cutting patterns or where precision is important in the function of a component part. Precision can also be repeated across a large number of parts with laser cutters. If consistency is important in production, then laser cutting might be the best option.
To Achieve High Quality Cut Edges
The quality of the finish at the cut edge when cutting with a laser does depend on the material that’s being cut and the laser and cutting process being used. However, under the right conditions, it is possible to create very smooth, burr-free cuts with laser cutters. With other cutting methods, finishing processes are often needed to achieve the same finish qualities.
Not only are better results achieved, but costs can be reduced, and time can be saved as well by avoiding further processing.
When Speed is Important
Laser cutters are great for one-off jobs, such as prototypes or design validation productions, and low to medium volume production runs. With computer assisted cutting, it’s often possible to begin production at very short notice. Equipment set up procedures that are needed with other methods are avoided, and production can begin very quickly.
Laser cutters can also be faster than other cutting methods over the course of an entire production run. If it’s important to complete a large production quickly, depending on the part being produced, it will often be quicker with laser cutting.
To Be Environmentally Friendly and for Safe Working Conditions
Laser cutters can be used for environmental and safety reasons.
While laser cutters themselves use a large amount of power, the entire laser cutting production process is often more environmentally friendly than other methods. Other stages associated with methods such as saw cutting and die punching can mean extra processing is required. This all contributes to power usage as well as the consumption of resources like water for cleaning.
There is also less material wastage with laser cutting. Computer aided design (CAD) design systems find the most efficient cutting methods, and this helps to reduce waste.
Laser cutting is also safer for the operatives at a production facility. Laser cutting takes place behind sophisticated guard systems. Cutting processes are also designed to be highly safe, making it much less likely that workers will be injured during production.
To Avoid Issues Associated with Other Cutting Methods
Laser cutting can be used when other cutting methods create problems.
If contamination is an issue, for example, laser cutting will help to avoid this. Contamination may occur at the cutting edge of certain materials with saw cutting, for example. Other cutting methods might cause different problems as well. In leather, for example, laser cutting can be used to avoid distortion issues that other cutting methods cause.
Due to the low set-up costs, rapid turnaround, low and medium-volume production flexibility, laser cut parts are widely used in a number of fields and applications.
Applications where laser cutting is common include:
Taking the automotive industry as an example, lasers can be used to cut interconnecting parts on most of the chassis, to carry out hydroformed part secondary processing or even to create air bags.
Laser cutting is often done with metal component parts, as these can pose a challenge for mechanical cutting or stamping. Large-scale production of parts made from plastic and other materials is also possible with laser cutting. However, this is less common, because laser cutting has certain limitations compared to certain fabrication technologies, such as plastic injection, for non-metallic parts.
Sales of laser cutting machines have increased on average 10% per year in a number of recent years. This tracks with the increased performance of laser cutting machines and technology vs the alternatives in the market.
Fig. 9: Automotive Industry's Dominance in Laser Cutting Technology Market
Cutting operations are essential aspects of part fabrication in the manufacturing sector. One of the main techniques for metal fabrication is sheet metal laser cutting. It is suitable for cutting pieces of metals, alloys, and non-metals.
Sheet metal laser cutting is a thermal cutting process involving beams of light (lasers) on the workpiece to melt or vaporize materials until the desired shape is obtained. This technique is one of the most effective for cutting sheet metal.
This article provides you with essential information regarding laser cutting sheet metal before utilizing it. Let’s get right into it.
Laser cutting metal involves using laser beams to melt metals and alloys, thereby causing smooth, sharp cuts. The laser cutting process consists of two operations working in synchrony.
The first involves the material absorbing the focused laser beam – the energy that causes the cut. The second involves the cutting nozzle, concentric to the lasers, providing the process gas required for the cutting. The gas protects the processing head from vapors and splashes and helps remove excesses from the kerf.
There are essentially three methods for laser cutting sheet metal.
The laser beam fusion cutting process uses an inert gas, mostly nitrogen. The low-reaction process gas continuously vaporizes the cutting gap of the material. As the molten material gets removed, inert gas prevents oxidation at the cutting edge without interfering with the process.
This laser cutting method is suitable for cutting flat, thin sheets of aluminum alloys and stainless steel that require high aesthetic appeal and fewer finishing operations.
As the name suggests, laser beam sublimation cutting evaporates the material. Instead of melting the material like other laser cutting processes, they are immediately changed from solid to gas – sublimation.
Like fusion cutting, laser beam sublimation cutting uses inert gases to blow the material’s vapor out of the kerf. So, there are no oxidants on the cutting edge. It is often used in cutting organic materials like wood, leather, textiles, etc.
Laser beam flame cutting uses a combustible gas – oxygen to thrust out the molten material. The laser heats the workpiece creating spontaneous combustion after melting the material. The oxygen gas provides more energy for the cutting process through oxidation – an exothermic reaction.
Flame cutting is ideal for cutting mild steel and fusible materials such as ceramics. This cutting process may cause burns on the cutting surface since the gas is an oxidant. Proper optimization of the process parameters will help prevent the formation of burrs.
Manufacturers usually use three different kinds of lasers for cutting materials. Each laser type has distinguishing features and is best suited to cutting specific materials. Below is an overview of the three types of lasers for cutting.
Fiber laser cutting machines use fiberglass for cutting. They generate very high power for powerful precision cuts. This laser belongs to a family of solid-state lasers from a “seed laser” enhanced by special glass fibers.
These lasers are suitable for cutting almost all materials, from metals to alloys, non-metals including wood, glass, and plastics. Besides cutting, they are ideal for other operations like annealing and engraving.
In addition, they are the most durable lasers, having an extended service life of more than 25,000 hours and requiring less maintenance.
CO2 lasers produce laser beams by running an electric current through a tube filled with a mixture of inert gases, mainly nitrogen and helium. They are the most common laser forms because they are efficient and cost-effective and cut several kinds of materials at high speed.
However, they produce less cutting power compared to fiber lasers. Hence they are not an excellent choice for sheet metal laser cutting. Typically, manufacturers prefer to use them for cutting non-metals and organic materials like wood, paper, acrylic, etc.
Crystal lasers generate their beams from either Nd: YAG (neodymium-doped yttrium aluminum garnet) or Nd: YVO (neodymium-doped yttrium ortho-vanadate, YVO4) crystals. However, the latter is more common.
These crystals produce beams with high cutting power. However, they are expensive and not durable, having a low half-life of about 8,000 to 15,000 hours. They are commonly adopted for cutting plastics, metals, and non-metals, including ceramics.
Let’s examine the benefits of laser cutting sheet metal to the manufacturing sector.
Laser cutting is a suitable fit for sheet metal cutting because of its extreme precision. The machines are equipped with the ability to make intricate cuts at extreme precision and accuracy. Industrially, laser cutting is the go-to technique for cutting sheet metal with specific details requiring tight tolerances.
Some cutters can make precise cuts with an accuracy of up to 0. inches. This is why it has remained a mainstay in most manufacturing companies. Since the lasers melt away the metal parts, the cutters produce little or no burring. Instead, it leaves a clean, smooth, and sharp edge.
Laser cutting runs by Computer Numerical Control (CNC) systems. Once the technical operator inputs the programs into the computer, the process runs independently. Therefore, it requires less human interference and overall labor. Also, there’s little or no margin for error with increased cutting efficiency.
There’s this misconception that laser cutting metal causes warping. However, that is untrue. The heat from laser cutting only affects minute portions of the material, not affecting tolerance.
Moreover, the laser cutting process is quick; the lasers heat and melt away the portions to be removed. So, the heat does not significantly affect the other parts of the material. In most cases, there is no distortion or warping of your materials.
Another critical advantage of this subtractive manufacturing method is its ability to work with an extensive array of materials. It easily cuts through each material, whether it is copper, aluminum, stainless steel, or even titanium. After all, it involves using lasers at very high temperatures to melt the material.
Indeed, laser cutting machines are expensive. However, compared to other CNC machines, it is more cost-effective. Moreover, it’s a single machine for all – that is, a single laser cutting machine is ideal for all your cutting operations. You do not need any machine modification for different cutting operations.
In addition, it’s durable. The device makes no contact with the materials you are cutting, so there is little, or no friction nor surface wear out. Also, it does not have multiple parts, so there are fewer maintenance and servicing requirements. In general, there’s a reduced operational cost of using a laser cutter compared to other customary manufacturing tools.
Besides the compatibility of laser cutting with most materials, the process is highly versatile. Unlike other devices, you can employ a laser cutter for several cutting functions, from simple to complex cuts and those requiring tight tolerances and intricate designs. This feature makes it an excellent choice for most industries.
Indeed, laser cutters require power to heat and melt materials effectively during cutting. However, the cutting technique is more energy efficient than other cutting methods.
In addition, unlike other machines, it has fewer moving parts, which means fewer energy requirements. Also, the machine’s high speed means quick cutting, saving time and energy.
The main disadvantages of sheet metal laser cutting include the following:
To effectively use a laser cutting machine, you need an expert who understands all its features and can quickly spot a problem to make appropriate corrections in time. If you do not set up the device correctly, you can damage your materials or the machine itself. So if you want to run a laser cutting service, you need to hire a professional.
Laser cutters have excellent compatibility with most materials, especially sheet metal. However, you might consider other cutting techniques when working with thick metals. In most manufacturing industries, laser cutters cut aluminum sheets with a maximum thickness of 15mm and 6mm for steel.
We’ve established that laser cutting involves using heat to melt the materials it cuts. As the machine melts each material, it releases harmful fumes and gases into the environment. Therefore, using these machines in a well-ventilated room is best advised.
The cost of procuring a high-quality laser cutter is dear. It’s more than $, almost twice the price of other cutting machines, like the water jet cutters. To run a business with a laser cutter, you must be ready to make the upfront investment.
To meet the precision and quality specifications of laser cutting for your parts, adhere to the following guideline.
The choice of material is essential for any manufacturing process. The material you select for your part depends on the properties you want for the final product. Besides metal sheets like aluminum and zinc, plastics and other polymers are good options for part fabrication, depending on your needs. Some properties manufacturers look for when choosing a material include flexibility, malleability, ductility, rigidity, etc.
Laser cutting machines only work with vector files. Therefore use software like Adobe illustrator to vectorize your designs. These files have formats like .ai, .step, .eps, etc.
Kerf is the portion of the material that evaporates as the laser beam focuses on the workpiece. When designing your part, you must factor the kerf into your designs.
Metal thickness is an essential factor to consider with laser cutting service. The thicker your metal sheets, the less likely the lasers penetrate.
Adequate spacing is vital for obtaining the best outcomes of laser cutting. The minimum distance in sheet metal laser cutting should equal your material’s thickness. For instance, if you are cutting a 2 mm metal sheet, you should leave a space of 2 mm.
Will Laser Cutters Damage My Materials?
No. Though many think the high temperature of laser cutting may damage materials. However, laser cutters are exact and work at incredible speed, such that the beam only melts out the parts you intend to cut. Also, the high speed means that your materials are not exposed to the high temperature for too long.
Should I Outsource or Get a Laser Cutting Machine for My Sheet Metal Parts?
Laser cutting techniques are essential for various manufacturing operations. It’s a highly effective process suitable for cutting most materials, especially sheet metals.
It is better to outsource your cutting operation if you run a small-scale manufacturing service. That is, hire a service for your laser cutting needs. It will help you cut costs, which can be channeled into other aspects of production. Contact Waken for your laser cutting and sheet metal fabrication needs.
Besides Laser Cutting, What Other Processes Can I Choose for My Project?
Laser cutting is not the only high-precision cutting method for industrial manufacturing. Should you choose not to use laser cutters for your fabrication or be conflicted on how to cut out shapes into your metal sheets? Below are excellent alternatives to choose from for your manufacturing requirements.
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