Sheet Metal Laser Cutting: Process, Pros & Cons
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.
What Is Sheet Metal Laser Cutting?
Subtractive manufacturing processes are critical for the modification of materials for part fabrication. Sheet metal laser cutting is one of the standard methods for cutting and removing components from a workpiece. The technique involves cutting out pieces of material using laser beams.
The laser cutting technique runs on computer numerical control (CNC) technology, which accounts for its impeccable precision. Before the CNC cutting or laser cutting operation, the operator must have input codes or programs detailing designs or patterns into the computer.
The Sheet Metal Laser Cutting Process
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.
1. Laser Beam Fusion Cutting
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.
2. Laser Beam Sublimation Cutting
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.
3. Laser Beam Flame Cutting
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.
Types Of Lasers For Sheet Metal Cutting
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.
1. Fiber Lasers
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.
2. CO2 Lasers
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.
3. Crystal Lasers (Nd: YAG or Nd: YVO)
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.
7 Benefits Of Sheet Metal Laser Cutting
Let’s examine the benefits of laser cutting sheet metal to the manufacturing sector.
1. High-Precision and Accuracy
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 0.0005 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.
2. Automated Process
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.
3. Damage Prevention
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.
4. Compatible With Most 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.
5. Relatively Low Cost
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.
6. High Versatility
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.
7. Low Energy Consumption
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 Cons Of Sheet Metal Laser Cutting
The main disadvantages of sheet metal laser cutting include the following:
1. Requires Technical Operator
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.
2. Limitations to Metal Thickness
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.
3. Release of Harmful Fumes and Gases
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.
4. High Initial Investment
The cost of procuring a high-quality laser cutter is dear. It’s 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.
Article source: waykenrm.com