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What is Laser Welding? How Does it Work?

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a laser welding machine in motion

Laser welding is a procedure in which metals or thermoplastics are connected to create a weld using a laser gleam. Due to the concentrated heat source, laser welding can be performed at high welding velocities in meters per minute in thin materials.

In thicker materials, it can generate slender, deep welds between parts with square edges. Laser welding works in two basic modes: keyhole welding and conduction restricted welding.

How the laser gleam will interact with the material you’re welding relies on the power density across the beam that hits the workpiece. In this article, we’ll discuss everything you need to know about laser welding. Let’s jump right in!


How Does It Work?

  • The pump source supplies the medium with energy. It stimulates the laser in a way that the electrons in the molecules are temporarily lifted to a higher energy state.
  • The electrons in the stimulated state cannot remain there as they drop drastically to a lower energy level.
  • They give off a photon as they lose the excess energy they get from the pump. It’s known as impromptu emission and the photons created by this process are the seed for the production of a laser.
  • The photons are given off by the impromptu discharge. Lastly, they hit other electrons present in the elevated energy states. When an approaching photon “knocks” the electron from the stimulated state to a lower level of energy, another photon is formed. These photons are consistent. It implies that they’re in phase, has a similar wavelength, and are moving in the same direction. The procedure is referred to as stimulated emission.
  • Photons are given off in every direction. Nonetheless, some of them move lengthwise to hit the vibrator mirrors, which bounce back via the medium. The vibrator mirrors determine the preferred amplification direction for the exciting discharge. There has to be a greater atoms percentage in the stimulated form than the lower energy levels for amplification to take place. This population inversion of excess atoms in the stimulated state causes several conditions needed for the generation of a laser.
  • The laser’s concentration spot is directed towards the workpiece surface which you’re welding. The concentration of light energy transforms into heat (thermal) energy at the surface. The heat makes the material thaw. It advances via the surface through a procedure known as surface conductivity. The gleam level of energy stays below the evaporation temperature of the workpiece material. The perfect thickness of the materials you’re welding should be 20mm. The energy of the laser is concentrated. It’s a benefit if you’re working with materials with high thermal conductivity.

Components of Laser Welding Systems

It comprises a motored guide, laser optics, and a worktable if need be. The half-finished products that you’re welding have to be fastened securely to enable an accurate joining.

Therefore, there’s a difference between motionless and mobile laser beam welding systems. When it comes to a mobile laser gleam welding system, the appliance is moved near merchandise. Immobile laser welding appliances come with a worktable that has a fastening tool.

The fastening and insertion of the immobile laser gleam welding systems can be automatic or motorized. Nonetheless, your worktable’s size restricts the measurements of the merchandise to be processed.

Apart from the accurately functioning servos of the robot hand and the welding optics, the regulation system is a crucial part in this welding system. It helps steer the arm to the designed spots and controls the laser gleam’s intensity and duration.

A cutting system is a perfect addition to a laser welding system. The perfect shapes cut through this system offer the precise geometry that a laser gleam welding machine may utilize to achieve optimal results.

What Are the Properties of Laser Gleam Welding?

  • Laser beam welding has a high power density that’s of the order 1 MW per square centimeter. Due to this high energy density, it has few heat-affected areas. The procedure also has a high heating and cooling rate.
  • The laser gleams generated stick together. They also have a similar wavelength (monochromatic).
  • You can use laser welding to weld smaller spot sizes. However, the sizes of the spots differ from 2 to 13 mm.
  • The penetration depth of laser beam welding relies on the amount of power supply and the concentration point location. It’s commensurate to the power supply amount. If the concentration point is kept somewhat beneath the workpiece surface, the penetration depth is maximized.
  • In laser welding, you can use constant or pulsed laser gleams. When laser welding slender materials, you’ll use millisecond-pulses, and if you want deep welds, use constant laser beams.
  • Laser beam welding is a versatile procedure as you can use it to weld stainless steel, aluminum, HSLA steel, carbon steel, and titanium. However, when laser welding carbon steel, you’ll have an issue with cracking because of the high cooling rate.

What Are the Different Types of Laser Welding?

You can carry out laser welding in two ways: Keyhole welding and heat conduction welding.

Thermal (Heat) Conduction Welding

In this procedure, the material gets heated above the metal’s thawing point. However, not to an extent that it evaporates. You can use this procedure for welds that don’t require high weld strength.

One benefit of thermal conduction welding is that the last weld comes out esthetically and highly smooth. For thermal conduction welding, it uses a low-power laser that ranges from 500 watts.

Keyhole Welding

In this procedure, the laser gleam heats the metal in a way that its contact surface evaporates and penetrates deep into the metal.

It forms a keyhole in which a plasma-like condition is created with temperatures increasing to more than 10,000K. This procedure needs high-powered lasers with a power output of above 105W/mm2.

laser welding machine

Image Credit: Aumm graphixphoto, Shutterstock

What’s the Maximum Speed When Laser Welding?

Besides exactness and minimal heat input, the functioning velocity is among the noticeable characteristics of laser beam welding. With the perfect circumstances, you can laser weld a lengthy, straight infinite seam at a velocity of 60 meters every minute.

The laser beam’s intensity differs. Therefore, the effect of the material utilized is less conclusive for the operating velocity of a laser gleam welding system. You can also connect thick sheets accurately within a couple of seconds.

What Temperatures Are Produced in Laser Gleam Welding?

If you’re welding a material, use a temperature that’s slightly above the material’s thawing point. The material’s thawing temperature is a restricting factor when it comes to conventional welding.

You cannot use every welding procedure to weld any material. It’s only in electric welding that there’s a scope in how intense the spot heat is, and if it can give off at its cathodes. Laser welding is distinct. In all the procedures, it has the greatest suppleness when it comes to the temperature used in welding.

The summary below shows some widely used materials and their thawing points. It also indicates the metals that you can weld using laser gleam welding

  • Plastics: From 150 to 350 degrees Celsius
  • Aluminum: 600 degrees Celsius
  • Glass: It ranges from 600 to 800 degrees Celsius
  • Copper: It starts from 1085 degrees Celsius
  • Steel: 1400 degrees Celsius

Practically, you can attain higher temperatures during laser gleam welding. However, this specter indicates how changeable this connection procedure is.

Where is Laser Welding Used?

Laser welding is increasingly being used in various industries. Some of the common areas where laser welding is used are:

  • Constructing tools
  • Automotive industry
  • Steel building
  • Shipbuilding

Due to its accuracy, laser welding is widely used in manufacturing tools. Therefore, it competes with the eroding procedure. The making of exact punching, casting, and pressing devices via subtractive or additive laser welding is the solution to the difficulties facing industries.

When it comes to the automobile industry, laser welding is used as it has a tool-free operation style. Contrary to electron beam welding, the laser doesn’t need any frequent wiping or replacing heads.  

In terms of accuracy and productivity, steel construction is experiencing completely fresh dimensions through laser welding. Thanks to laser beam welding, the quick processing of broadsheets in high-endurances is now a reality.

The same also applies to ship making: Here it’s all about accuracy – fabricated parts like rudders, drive screws, and control attain their desired tolerance via laser welding. Due to this, the ships achieve higher speeds and consume less fuel.

person using laser welding machine

Image Credit: Mr.1, Shutterstock

Advantages of Laser Welding

It’s accurate

Laser welding provides a high accuracy level and control. It implies that you can use it to weld even the smallest parts together, without leading to damage.

It can produce convoluted joints

With laser welding, you can weld different materials. Also, you can weld areas that would be too hard to get to if you use more conventional welding approaches.

It uses less heat

It lessens the contortion of parts as it applies less heat. That’s why it’s the most preferred method when it comes to producing luxury merchandise like custom-made jewelry.

It produces repeatable and consistent weld seams

It’s a quicker welding approach as compared to other conventional techniques. It’s also more versatile. You can also use a laser for drilling and cutting too. Its repeatability and versatility assist businesses in making considerable reductions in unit cost.

It produces strong weld seams

Lasers offer high-quality weld seams that are strong, and that’s why it’s preferred by manufacturers.

Disadvantages of Laser Welding

  • The gear used in laser beam welding is expensive, and the initial cost is also high
  • The welding thickness is restricted to 19 mm
  • Laser beam welding has low energy conversion efficiency. It’s typically less than 10%
  • To carry out laser beam welding, highly skilled labor is needed
close up laser welding machine

Image Credit: Aumm graphixphoto, Shutterstock

FAQs

How do you weld using a laser?

With the laser welding procedure, the energy reaches the workpiece only via thermal (heat) conduction. The welding depth required for this procedure is usually less than 2 mm.

The laser gleam thaws the materials you’re connecting along the joint. Then, the melts flow into one another and the solidified melt binds the materials lastingly.

Is laser welding potent?

In laser welding, you’ll get more precise weld seams, and the finish is exceptional. The welds are also strong. Therefore, this manufacturing procedure is great for fine components. You can also use it in areas with restricted access.

Can aluminum be laser weld?

Laser welding is commonly used to connect aluminum and its amalgams.

Can you use filler in laser welding?

You can carry out laser welding with filler material. It can be done with wire or powder. Nonetheless, most of the industrial laser welding applications utilize wire.

Where is laser gleam welding mostly commonly used?

Laser welding provides a concentrated heat source and forms a potent seam at high velocity. Its procedures and applications are mostly used in the automobile industry. This is where lasers increase productivity at a low cost if you’re laser welding automobile components like a door, roof, or filter assemblies together.

Why do we use lasers for welding?

The highly focused heat source produced by a laser can form a keyhole. As a result, laser welding creates weld metals in small volumes. It conveys only a restricted amount of heat into the encompassing material, and subsequently, the samples contort less as compared to those welded using numerous procedures.

A Quick Reference Guide

Electron Beam Welding
  • Uses a focused gleam of light to influence the weld
  • It utilizes filler material
  • It has greater weld velocity and it’s versatile as you can use it with robot systems
  • It’s carried out in a vacuum surrounding. It ensures that no impurities are left
Laser Beam Welding
  • You can use it on a moving electron welding gun with auto-join tracking. It doesn’t have radiation problems
  • It doesn’t use filler material
  • It’s used in more critical applications where it generates higher weld speeds and contorts less as compared to laser beam welding
  • You can laser weld in the air as it has no radiation risks

Conclusion

You can use laser gleam welding for highly accurate weld seams. Since no electrode is used, the final weld seam is lightweight but potent. Certainly, the first investment is costly.

Nonetheless, a laser weld’s quality and properties cannot be reproduced easily. Since lasers are increasingly becoming more energy-efficient and strong, it implies that the future of laser welding is certainly radiant!


Featured Image Credit: Aumm graphixphoto, Shutterstock

Cameron Dekker
 

Cameron grew up in Allentown, Pennsylvania, a once-proud steel town on the Lehigh River, where he got a taste of TIG welding in his high school shop class. He holds certificates for Certified WeldingEducator (CWE) and Certified Resistance Welding Technician (CRWT) from the American Welding Institute. His interests include scuba diving, sculpture, and kayaking.