Cutting is the oldest and most used process in manufacturing and fabrication. From knives to hacksaws to advanced technologies like Laser and Plasma cutting, it has always been a staple in the workshop.
The push to develop better and more precise cutting methods has given rise to the extremely precise form of cutting in use today. One, in particular, Laser Cutting, is making waves in the industry as the gold standard for creating accurate sheet metal parts.
In this article, we are going to explore laser cutting based on our ten years’ manufacturing experience. We will go through everything from how Laser cutting works, to how best to design parts for laser cutting.
So, let me start at the very beginning. What is Laser Cutting?
What is Laser Cutting?
Laser cutting is a thermal separation process that employs a laser as a cutting tool to cut, trim or shape various sheet metal materials. The laser melts or vaporizes the material to be cut along a predetermined path to form custom shapes or designs.
This is also a CNC procedure, which means a computer directs the motion of the cutting head during the cutting process. This ensures that the machine stays on track and produces accurate, precise parts.
This is one of the typical manufacturing processes to create custom machined parts, including prototyping, low volume as well as mass production.
Advantages of Laser Cutting
Laser cutting is very popular in the industry today, especially in accuracy-sensitive applications. Its popularity is due to the advantages it has over other conventional cutting methods.
Let’s look at some of these benefits.
√ High Precision and Accuracy
Laser cutting is unrivaled among all other cutting methods when it comes to precision. The CNC-controlled laser can achieve cuts with a tolerance of up to 0.003mm, making it the obvious choice for precise applications.
Also, the laser melts or vaporizes all the excess materials from the edge of the cut, leaving a smooth and neat finish. This negates the need for additional post-processing.
√ High Cutting Versatility
Laser cutting machines are highly versatile, especially CO2 lasers. They can be used in cutting anything from metals, to plastics and even wood without requiring extensive modifications.
Furthermore, with such a machine, there are many other processes available to users e.g., Etching, engraving, etc.
√ Low Waste Generation
When properly designed, laser cutting operations are very efficient with material usage leaving little or no waste behind.
By good design and using a technique called nesting, several designs can be cut at once from a single material. This leads to lower power and material requirements, lower production costs, and a faster turnaround time.
√ High Turnaround Speed
This is a very fast fabrication process. It doesn’t require any sort of tooling or modification for it to start operation. The only factors influencing the speed of the project are the complexity of the design and the thickness of the material.
Once the schematics are loaded into the CNC router, cutting can begin.
Disadvantages of Laser Cutting
Like every other fabrication method, laser cutting also has its disadvantages. Some of these disadvantages are:
It is not suitable for some materials, especially reflective ones.
There is a high upfront cost associated with acquiring a laser cutting machine.
It is limited to materials of a certain thickness.
It requires a trained operator to safely operate the laser cutting machine.
Types of Lasers Cutting Machines
As I mentioned earlier, laser cutting machines are classified based on the active laser medium. Based on this classification, there are three main types of laser machines in use in the industry.
CO2 lasers are gas lasers. It uses a discharge of electric current in the gas to produce the coherent light for the laser.
The CO2 laser is a very versatile laser capable of cutting a wide range of materials. They are commonly used for cutting, boring, and engraving operations.
They are among the most used in the industry due to their versatility and relative cheapness.
√ Fiber Lasers (Nd & Nd: YAG)
Neodymium and Neodymium (Nd) and Neodymium-doped yttrium aluminum garnet (Nd:YAG) Lasers are fiber lasers. The active material in both is an optical fiber doped with a rare earth element.
A seed laser produces the laser beam, then the laser is amplified within the fiber. This enables a very high optical gain which results in high power.
It also produces a very small spot size which increases its accuracy and suitability for cutting reflective materials. Fiber lasers are used for applications that require high energy like boring, scribing, and engraving of select metals.
How does Laser Cutting Work?
There are many types of Laser cutting machines out there operating with different procedures. However, their mode of operation remains the same.
Let’s go through the steps.
Step1: Beam Generation
The process starts with a single or a seed light beam. A laser resonator generates this beam by stimulating a lasing material using electrical discharges or lamps within a container. Generally, these lasing materials are grouped into three classes: Solid-state laser, gas laser, and Liquid lasers.
We’ll talk more about these materials later.
Step2: Beam Propagation
A series of mirrors reflect and amplify the light beam inside the resonator. The light beam then gains enough energy and intensity to escape as a stream of monochromatic coherent light. Another mirror then directs this light to the cutting head.
At the cutting head, a special lens focuses the laser into a thin beam through the cutting head’s nozzle. This increases intensity of the laser increases its power and directs it onto the surface of the workpiece to be cut.
Step3: Beam Movement
The movement of the laser beam depends on the machine’s configuration. There are several different configurations.
In some machines, the cutting head moves relative to the workpiece. While in some, the workpiece moves relative to the cutting head, or they move relative to each other. The relative movement enables the laser to trace out the cutting path.
Step4: Localized Melting, Heating, and Material Ejection
When the laser reaches the material surface, the small intense beam focuses all its energy on a localized surface. This transfer of energy increases the thermal energy of the localized surface, melting or vaporizing it.
Depending on the laser beam’s intensity, the material can be cut through, cut to a specific depth(engrave), or scorched to create a pattern.
These lasers can cut the workpiece in one of two ways. They can come out in short powerful bursts as pulsed beams, or they can be produced in continuous, high power output as a continuous wave.
Pulsed beams are more suitable for high-speed, high-power operations like boring, drilling, etc. While continuous-wave lasers are better suited for cutting operations.
As the beam melts the surface, an assist gas (usually inert) clears the molten metal from the workpiece. The assist gas also cools the machine and protects the laser from damage.
Typical Materials For Laser Cutting
Materials that can be cut by lasers include:
Metal: Stainless steel, Aluminum, Titanium, and Copper.
Although laser cutting is suitable for a wide range of materials, there are still certain restrictions. Some materials cannot undergo Laser cutting because they are flammable. Also, certain materials can release harmful gases when cut.
These materials include:
Any material containing halogens
Typical Cutting Operation
Different materials require different Laser setups and cutting methods to get the best results.
So, to get the best cut possible, you have to select the appropriate cutting process. Let’s look at some of the cutting processes available to choose from.
√ Oxidation Cutting
This process can be done with CO2 and Nd: YAG lasers. It uses oxygen as an assist gas to accelerate the cutting process. The oxygen reacts with the heat generated by the laser to increase the melting rate of the material and thereby speed up the cutting process.
The cutting process generates an oxide layer on the cut surface, but it can easily be removed later. Oxidation cutting is suitable for metals like mild and carbon steel.
√ Fusion Cutting
Fusion cutting uses an inert assist gas like Nitrogen to blow the molten metal away from the cutting zone during laser cutting. Blowing the metal away reduces the power requirements of the cutting machine and leaves a smooth finish.
It is suitable for cutting a wide range of metals and thermoplastics. Just note that the assist gas used must not be reactive with the metal being cut.
√ Evaporating Cutting
Materials that do not melt like wood and thermoset plastics are usually cut with this process. Here, the laser doesn’t melt the materials along the cutting path.
Instead, it evaporates the material, leaving behind a smooth and glossy finish.
Scribing is used in producing grooves or penetrations in materials like ceramics and silicon wafers. The objective of this process is to weaken the material along the structural line, where it can be mechanically broken later.
Types of Laser Cutting Application
There are many applications for lasers in the workshop apart from cutting. By modifying the intensity of the laser beam, we can gain use it for many other operations.
Some of these applications are:
√ Laser Engraving
Laser engraving creates a pattern on the workpiece by removing material at a specified depth. It is used in creating personalized designs for objects like plaques, trophies, etc.
√ Laser Boring
This process uses a high-power laser to create or drill holes in the workpiece. Using pulses of laser light, it can create highly precise holes in the workpiece by vaporizing the excess materials.
√ Laser Marking
This procedure is similar to laser engraving, except it creates designs that are only surface deep. Laser marking comprises a series of procedures like staining, ablation, etching, etc. that are used in creating these designs usually by burning or chemically modifying the surface of the material.
Tips That Can Help You in Laser Cutting Operations
Designing parts and cutting them using a Laser Cutting machine is a fairly straightforward process. However, new and inexperienced users can still run into a bit of trouble or get stuck.
To help with this, here are some tips and tricks that can aid in designing and cutting the best parts possible.
Use high-quality software like AutoCAD or CorelDraw when designing models so you can take advantage of the inbuilt functionalities.
Employ different color schemes for different features on your drawing to avoid confusion. i.e., Use black for cutting lines while using yellow for engraved features.
Clean up all excess and unnecessary lines and features in the drawings before sending them to the laser cutting machines.
Avoid using double and overlapping lines in the part designs.
Always test out designs with a scale model or mockup before printing them at full scale.
Keep the laser’s lenses clean at all times to avoid damage and poor cutting quality.
Before cutting, make sure you choose the right quality material that is compatible with your Laser Cutting machine.
Laser Cutting remains one of the most cost-effective methods for fabricating accurate sheet metal parts. The accuracy it provides makes the cost worth it.
As a professional prototytping shop, we work with a reliable partner that has some of the best Laser cutting machines, we can offer professional low volum sheet metal fabrication services in China. With us, you can be sure you’ll get the quality you deserve at the best price possible. If you are looking at the high cost as a high barrier to entry, don’t worry we are here to help.
Contact us today with your projects, no matter it is an protototyping or low volumn quantity, we can put you in touch with our engineers for a price quote.