What is laser welding?

Interested in laser welding? Read this post to quickly gain a general view of its principles and types. Best laser welders for beginners will also be introduced.

Table of Contents

What is laser welding?

How does laser welding work?

oHeat conduction laser welding

oDeep penetration laser welding

Laser welding with other weld processes

Weld joint configurations

Types of welding lasers

oNd: YAG Laser

oFiber Laser 

oDiode Laser

Best laser welder for beginners

Conclusion

Need welding services from China?

What is laser welding?

Laser welding is a process that uses the high-intensity laser beam to join metals or thermoplastics together. The laser weld is formed as the intense laser light rapidly heats the material – typically calculated in milliseconds.

Laser welding allows precise welding in small and hard-to-reach areas and is a promising joining technology with high quality, high precision, high speed, good flexibility, and low distortion.

How does laser welding work?

Laser welding can be achieved by continuous or pulsed laser beams.

The principle of laser welding can be divided into heat conduction welding and deep penetration laser welding (or keyhole welding). Laser welding can be combined with conventional welding processes, and be used for soldering.

When the power density is less than 104 ~ 105 W / cm2, it is heat conduction welding. At this time, the welding depth is shallow. It can easily join thin parts and visible edges. Its depth normally is below 2.5mm and max. depth-to-width (D/W) ratio is 3:1.

When the power density is more than 105 ~ 107 W / cm2, the metal surface is recessed into “hole” when heating, forming deep penetration welding. Deep penetration welding features fast welding speed and large depth-to-width (D/W) ratio. The depth-to-width ratio of the weld can be up to 12: 1, and the current maximum welding depth can reach 51mm.

Heat conduction laser welding

In heat conduction laser welding, the laser beam melts the mating parts along a common joint. The molten materials flow and solidify to form the weld.

During this process, the laser energy is shifted into the workpieces solely through heat conduction. The heat conductivity of the workpiece limits the maximum weld depth. Thus the width of the weld is always greater than its depth.

Typically this can be used for applications that require an aesthetic weld or when particulates are a concern, such as certain battery sealing applications.

Deep penetration laser welding

When the power density is great enough, the heat is not able to dissipate quickly enough. The workpiece goes beyond just melting. It vaporizes.

The vaporizing metal or plasma expands and creates a keyhole or tunnel from the surface down to the depths of the weld.

As the laser beam is moved across the surface of the workpiece, the keyhole follows and creates a deep and narrow weld.

Laser welding with other weld processes

Laser welding is often used in conjunction with arc welding to create Hybrid Laser Arc Welding.

In hybrid laser arc welding, any one of the arc welding processes like MIG, TIG or SAW is used with deep penetration laser welding.

The resultant weld will have deep penetrating joints, thanks to the laser weld and will also have improved tolerance to joint fit-up. Other undesirable effects like cracking and internal porosity are also reduced.

Weld joint configurations

Welding joint is an arrangement or configuration of the two pieces of metal (or more) that will be welded together.

The joint configuration is an important factor in determining whether a welded joint can withstand the load imposed on it

There are 5 basic joints that are most commonly known and applied according to the American Welding Society (AWS) and many other standards.