‘Laser’ is the pretty name of a complex process: Light Amplification by Stimulated Emission of Radiation.
Laser was discovered around 1960 by John L. Emmett and John H. Nuckolls. They’d built on the1900 theories of Max Plank, and the 1918 follow-up work of Einstein. These leaders were followed by a long line of scientists and engineers. Each contributing to the perfection of the Laser devices we work with today.
The newly discovered Laser soon found its way into many industries. Welding was among the first to adopt the up-and-coming technology. Its usage was limited though by factors like cost, size, and the precision of the weld.
Today, these wrinkles are mostly ironed out. Laser welding machines are abundant in factories, manufacturing plants, and academic laboratories of engineering institutes. They even found their way into smaller facilities and workshops.
Laser welds are immaculate, quick, and aesthetically pleasing. The precision of laser welding machines allows processes to be fully automated. Thus, increasing production and cutting back on time and expenses.
If you’re wondering how does laser welding work? Here’s a comprehensive guide, with everything you need to know.
Table of Contents
How Does Laser Welding Work?
The goal of welding two metals is always applying a high energy source to melt the metals. This is true for the heat energy coming out of an oxyacetylene torch, the electricity from arc welders, and the focused light energy from a Laser welder.
The energy of light might not seem as powerful as torch heat, or an electric arc. But it’s the focusing of this light energy that gives it all that might.
To fully understand how laser welding works, we should first take a look at its scientific principle. Then, we can demystify its components, as well as its various configurations.
The Scientific Principle of Laser
When electrons receive excessive energy they ‘get excited’. They even leave their normal orbits and spin at a higher energy level. And once they return to their steady-state, they emit a photon of light.
Natural light is made from these photons. They travel in all directions and have absolutely no regard for what their fellow photons are doing. Aligning these photons harnesses an immense amount of energy.
Firing a pulse of aligned photons is what gives Laser its impressive power.
The Components of a Laser Welding Machine
This is a breakdown of a medium-sized, semi-automated Laser welding machine.
- Power source
- Laser generator
- Shielding gas
- Chilling/cooling system
- Laser transmission system
- CAD/CAM systems
- Mounts, feeding mechanisms, and Frames for the workpiece
These components would vary depending on the type of work performed and the specialization of the facility.
The shielding gas is employed to protect the newly formed weld from the effects of the atmospheric air, in a manner similar to the way gas is used in arc welding. Otherwise, the welds become porous, brittle, and unreliable.
If a shielding gas is off the table, the only other option is to perform these welds in a vacuum. This, of course, adds complexity to the situation, and using a shielding gas is much easier in comparison.
Using Computer-Aided Design (CAD) and Computer-Aided Manufacturing (CAM) systems is crucial in the automation of Laser welding systems.
These are the main methods to design and control laser welding. These are also how productivity and accuracy are optimized.
The Set-Up of a Laser Welding Unit
There are several levels of automation for Laser welding machines. Some Compact Laser Welders allow a measure of manual control, where the operator adjusts the positioning and movement of the workpiece.
While other Integrated Laser Welding Units, are the size of the room and handle a bunch of industrial processes. From 2D and 3D-cutting, to 360-degree welding, and metal deposition.
These systems contribute hugely to streamlining production.
Generally speaking, there are three main categories of Laser welders.
- Manual systems
- Semi-automated systems
- Fully-automated systems
The final choice of which set up to use; depends largely on the production scale at your facility. Whether that is the current manufacturing capacity or the planned expansion of the business.
The Main Types of Lasers
The laser beam can be produced through several different processes. Machines are often named after the scientific method employed for creating the Laser beam.
Not all Laser beams are created equal, and they have different temperaments just like Pitbulls. That’s why each type of Laser is recommended for specific applications.
Here are the four main types of Lasers.
CO2 Laser is the trailblazer of these machines. However, it didn’t become dated and archaic with the passing of time. Actually, it holds it’s own quite nicely among the new-age Laser welders.
The medium used is a mixture of CO2, Nitrogen, and Helium. Exciting these atoms quickly ends up in a sustainable pulse of Laser.
This type of Laser is capable of welding thick pieces of metal with impressive ease. It’s also highly versatile and gives an equally admirable performance with thin sheets.
It has an average efficiency of 7%.
Solid State/Nd: YAG Laser
Neodymium-doped Yttrium Aluminum Garnet (Nd: YAG). This is the name of the crystal and the stimulant that excites it to emit laser.
The detailed events leading to the production of the beam, aren’t as relevant here, as the quality of the produced Laser.
Nd: YAG Laser is easier to control than CO2, the set up is straightforward, and it can work in pulsed mode. On the flip side, the beam quality is less than the other types. This comes with predictably low efficiency of 3-4%.
The trip of Fiber Laser production here is pretty short and goes straight from the diodes to the fiber optic system.
Transmitting the Laser beam to the point of application is easy, and the efficiency of its production is one of the highest. It registers a noteworthy 25%.
The Laser beam quality is superlative. It’s versatile and easily handles thin and thick pieces. It also has high penetration capability, in case a deep weld is required.
This is an improvement on the classic Nd: YAG configuration. Instead of applying the electron stimulation to a crystal rod, a disc is used.
This increases the efficiency of the Laser device significantly. Which in turn, improves the quality of the beam. A Disc Laser device has the practical set up of Nd:YAG, in addition to the focus and intensity of CO2 Laser.
The Basic Parameters of a Laser Beam
Full mastery of any machine means understanding what each setting does to the workpiece at hand.
It takes a bit of experimentation, of course. But getting to know the basics, saves a lot of time and effort later on.
Laser is delivered in one of two forms: pulsed or continuous. The main difference between them is in the amount of energy passed onto the metal in a specific duration.
The direct implication is the amount of heat that’s induced in the metal.
Pulsed Laser delivered a controlled amount of energy. It’s sufficient to do the weld, but not excessive to the point of damaging thin sheet metal. That’s why it’s often used for delicate precise work. A common example is jewelry making.
Continuous-wave Laser is more suitable for thick refractory metals. It penetrates the workpiece to significant depths and gets the joints welded in seconds.
This type of device is often larger and more expensive than the pulsed Laser type.
Pulse-Frequency and Waveform
This is the fine-tuning of the Laser output delivered to the workpiece. The correct adjustment of these parameters reflects on the neatness and strength of the welded seams.
These two settings are related to how much energy goes into each Laser pulse.
High frequencies and unsuitable waveforms limit the amount of energy that reaches the metals. If it becomes too low, the weld would be too weak.
Most often, it breaks up and fails. The worst part is that welds could appear to be solid, while they could snap after a short time.
The focal length of any Laser device describes the optimal length from the Laser head where the beam is in sharp focus. Focal length also puts some constraints on the correct placement of the workpiece.
A short focus usually gives precise narrow welds, as the point of focus is at its sharpest.
Longer focal lengths often give wider beads with shallow penetration.
The shallow weld shouldn’t be considered a drawback, as sometimes the project at hand demands that. Thin sheet metals, for example, would be completely spoiled by deep penetration.
A bright beam is like an extra-hot torch. It penetrates deeper and gets the job done with a narrower bead.
Higher beam quality usually comes at a higher price. That’s why many welders opt for ‘rougher’ beams if their work doesn’t require high-precision.
As opposed to the general perception, energy consumption isn’t higher in brighter beams. This factor depends more on the efficiency of beam production.
Choosing the right energy level, or beam intensity, should be done together with adjusting the beam diameter. This could be automated in a more advanced set-up.
However, it’s important to know the essentials of a good weld, even if the machine does the groundwork.
A larger-than-necessary beam would easily botch a weld. And on the flip side, a beam that’s smaller than the needed weld, would end up in a weak or loose join. Beam diameters between 0.2 and 2.0 mm are often used.
What is Laser Welding Used for?
The benefits of using Laser welding are mainly speed, accessibility, and precision. Here are some of the main applications of Laser welding.
Assembling Automotive Components
The nature of automotive parts is challenging for conventional welding methods. It’s primarily thin sheet metal, includes aluminum parts, has other non-ferrous metals, and often can’t tolerate too much heat.
This comes with a bunch of other accessibility issues. For starters, car frames contain numerous hard to reach points. And on top of that, many spots can’t tolerate excessive heating.
Several of the auto body welds are visible, and so, require a higher level of finishing and pretty welds.
All these constraints are nightmarish for arc welders, but dealing with them is a walk in the park for Laser welders.
High-precision delicate welding is one of the excellent points of Laser welding. The fact that it also comes with limited overheating in the workpiece is a huge plus.
These features make Laser welding the perfect choice for jewelry making. There are also some secondary perks to having a Laser device. A jeweler can use it for cutting, embossing, or engraving a piece.
Welding Curved Contours
This is another area where conventional welding falls short and Laser welding saves the day. Pretty seams aren’t the only specialization of Laser welds.
Laser can follow any complex contour and leave a narrow bead of sturdy welding. The joined parts often fit like a glove, and if you’re into regular welding, you’d know how awesome this is.
Repetitive Production-Line Welds
Laser welding lends itself easily to full automation. Factories that need to assemble or build specific products repeatedly benefit a lot from this.
Processes are known to improve by up to 86% once Laser welding is introduced. This translates directly to financial gains for obvious reasons.
It’s also noticed that the automation of the welding stage of manufacturing, improved the overall quality of products.
So on top of process optimization, there’s also the added gain of customer satisfaction. Not bad at all!
Welding Hi-Tech Components
This is where precision work, and the lowest amount of heat output, are in demand. Some industries that benefit from laser welding are medical devices, sensitive electronic appliances, aerospace components, and ship-building.
The latest technology in the manufacturing of these devices and their components is precise to the micrometer. Glitches as small as a millimeter could spoil expensive components and they simply become waste.
Automated Laser welding ensures that these parts are joined exactly as they need. The welds are often minute, but still sturdy and uncontaminated.
Welding and assembling these Hi-Tech parts often includes joining two incompatible metals together. This is also the turf of Laser welding, and it gets done like a breeze.
What Is the Cost of Laser Welding?
What is the cost of Laser Welding? The current market prices for laser welding machines range from $15,000-$30,000. Specialized industrial welders and customized units could go north of the $100,000 mark.
Laser welders are a serious capital investment.
Assuming 70% uptime of the Laser welder, the running costs can be estimated, to get an idea of the economics.
The cost of operation of a 5 KW Laser unit, including the cooling system, consumables, and utilities, is approximately $10 per hour.
For a 2.5 KW Laser welder, the gross operating costs could add up to $6 per hour.
The idea is to calculate the workflow and expected gains so that this initial investment is justified. Otherwise, alternative arc welding methods should be sufficient. Cost-effectiveness is key here.
Related reading: Is Welding Expensive? Breaking Down The Cost
What Are the Advantages and Disadvantages of Laser Welding?
Laser welding joins metals perfectly, and it does so, in a fraction of the time taken by the usual welding methods.
The differences between laser and conventional welding are significant. But it does have a few limitations worth noting. Here’s a brief rundown of the good and bad in Laser welding.
Laser welding vs. Conventional welding >> Check out the video below:
The Advantages of Laser Welding
- The laser weld is aesthetically perfect
- The welded piece doesn’t need extra grinding and finishing
- No electrodes are needed for welding
- No consumables are used
- Laser welding can work on pieces needing high accuracy
- The turn-around-time of Laser welding is high
- The Laser weld is done much faster than a conventional weld
- The Up-time of the Laser welding machine could reach 85%
- Laser machines can easily fit in automated processes
- The laser weld is significantly narrower than the conventional weld
- A laser beam can reach extremely difficult joints
- Curved surfaces are easy to weld using a Laser, contrary to regular welding
- Laser welding is versatile and can easily work on any metal
- A handheld laser welder offers more working flexibility
- Laser welding doesn’t overheat the workpiece
- The same machine can be used for Laser cutting
- Laser welding can easily be fully-automated
The Disadvantages of Laser Welding
- The capital and operating costs of Laser welding machines are significant
- The head of the Laser machine can easily be compromised by metal splatter
- The optical parts of the Laser machine need frequent maintenance
- The average Laser machine is much larger in size than a regular welder
- Laser welding needs extra training
Is Laser Welding Better Than Electron Beam Welding?
While Laser Welding uses light for energy, Electron Beam Welding (EBW) employs the power of excited electrons guided by magnetic fields. Both are relatively recent methods that rely heavily on cutting edge science and tech.
The increasing popularity of laser and EB welding encouraged us to hold a comparison of their performances.
The depth and thinness of penetration of the EB weld is its strongest suit. Then comes it’s extreme neatness and high precision.
The welds are almost seamless. Laser welding holds its own in that regard, but there’s a clear advantage with EBW.
One of the downsides of EBW is its need to work in a vacuum. This limits the size of the workpieces that can fit inside the vacuum chamber. And then, there’s the waiting time to prepare the chamber before the weld can start.
Laser welders work nicely in any setting. They’re also free from the limitations on workpiece sizes. That’s why Laser welding is more abundant in factories where there’s a welding line of mammoth-sized frames.
EBW has specific applications in extremely high tech applications like space crafts and cryogenic equipment.
The next limitation is the need for high voltage to operate the machine. In addition to the sophisticated monitoring and processing devices attached to the welding unit. It also necessitates the presence of a highly skilled technician to run the show.
Laser welding lends itself easily to moderate skills. In fact, the automated system is quite easy to operate.
The last point has to do with cost. The Laser welder comes in thousands of dollars, while the EBW jumps to the millions. The operating costs remain proportional to these initial costs.
It’s fair to say that laser welding and electron beam welding are different ball games. Each plays in its league.
Is Laser Welding Better Than Ultrasonic Welding?
Ultrasonic welding utilizes another scientific principle, which is sound. A boosted ultrasound signal is quite powerful. It easily generates sufficient heat to melt metals and achieve a nice weld.
The main advantage of an ultrasonic welder is that it needs little energy to work. And it can work well without overheating the workpiece. It can also weld incompatible materials together effortlessly. It is especially clever in welding thin sheets of light metals like aluminum.
It also built a sound reputation (pun totally intended!) for welding plastics and fabrics. This has to do with the low-temperature range it excels in.
All this is done in seconds, as this is a practical machine that doesn’t need too much time to prepare. Also, the capital costs for running an ultrasonic welder aren’t intimidating.
That’s why it found its way to many brand manufacturing quarters, like New Balance.
Laser and Ultrasonic welding seem to be vastly different, but they could cross paths here and there. In auto body fabrication, especially, both technologies could work well.
The initial investment in a Laser welding machine could be sizable, but the potential gains aren’t any less significant.
Laser welding is clearly superior to many other types of conventional welding. Using technical advancements to improve the quality of your work, and to optimize your operations is something to look forward to. Even better, to plan for.
This courageous move starts with gathering the necessary information. It starts with a simple question: how does Laser welding work? Hopefully, this comprehensive guide has answered this question fully.