Laser welding is a welding technology widely used in the aerospace and automotive part manufacturing industry due to its advantages such as precision, speed, and low thermal stress.

A laser welding process diagram
A laser welding process diagram

It is a go-to welding technique for these industries, but you should only select it after properly understanding how it works and comparing it with other welding techniques. This article is an ultimate laser welding guide for manufacturers who want to use laser welding. Let us go. 

What is Laser Welding?

Laser welding as a non contact process
Laser welding as a non contact process

Laser welding uses a laser beam emitted by a laser welding machine and focuses on the joint between two parts (sometimes with a filler rod) to join them together. 

The laser beam heats the joint above the parts’ melting points, forming a molten metal which on cooling solidifies to form a laser-welded part.

The laser welding process is advantageous because it is non-contact, you can laser beam focus on small spots and close control of applied energy. As a result, the welding technology is precise and causes low heat-affected zones not seen in other welding technologies. 

Laser welding is applicable in aerospace and automotive industries for joining aluminum parts known for being difficult to weld by other welding technologies. Other industries using the process are medical and electronics part manufacturing.

How Does the Laser Welding Process Work

Welding a reflective surface
Welding a reflective surface

The general steps to how the laser welding process work is highlighted below:

Preparing the parts

Clean the parts to remove impurities like oil and grease that can affect the welding process. Afterward, dry the parts. 

Position the parts

This depends on the machine, but you should position the parts accurately. The contact line between the two parts is closed and gap-free for better-welded joints. Afterward, use fasteners or clamps to hold the two in place and keep them stable during welding.

Set up the machine

This involves adjusting the laser beam focal point using the optical gear in the welding torch. Adjusting the beam power testing it on trial parts and ensuring the laser beam energy is sufficient to melt the two materials. 

Begin the welding process

Focus the laser beam at the beginning of the contact line of the two parts till an appropriate melt pool forms then talk it all to the other side steadily. Allow the welded joint to cool naturally or use other cooling techniques such as water quenching. 

Types of Laser Welding Processes

A laser welding operation
A laser welding operation

Different laser welding techniques are used to join different parts and achieve different quality of welded joints. They are:

Keyhole Welding

Keyhole welding involves heating a part to a high temperature (up to 10000K) using a high-power laser (>105W/mm2) which creates a keyhole hence the name keyhole laser welding. 

It is applicable for joining thin parts making it suitable for electronic and automotive parts. 

Laser Brazing

In laser brazing, you heat the workpiece to form a molten surface and heat a filler material (with a low melting point) on the molten surface. On cooling this forms a strong welded joint.

The process can join two parts made of dissimilar materials due to the use of filler material and the welded parts are less susceptible to distortion. 

Laser brazing is applicable in the automotive part because it makes use of different materials.

Hybrid Welding

In hybrid welding, you combine laser beam welding and another welding technology (common ones being Gas Tungsten Arc Welding and Gas Metal Arc Welding) and enjoy the benefits of both methods like improved welding quality and production efficiency.

Heat Conduction Welding

In heat conduction welding, you use the laser beam generated by a low-power laser to heat the parts’ surfaces beyond their melting point. It is not the perfect laser welding technique for parts that require high weld strength but it can create an aesthetically appealing welded joint.

Percussion Welding

Percussion welding or impact welding involves pulsing the laser beam at a high frequency and using it to join two materials quickly. It is applicable in joining dissimilar materials such as aluminum and steel with different thermal properties

What Materials Can Be Joined with Laser Welding?

Laser welding technology
Laser welding technology

The laser beam welding techniques are suitable for working with these categories of materials:

Metal 

Metal parts made of aluminum, copper, steel, titanium, and nickel are compatible with the laser welding process. Aluminum is the most common material for the welding technology. 

Plastics

Polycarbonate, nylon, and ABS are examples of thermoplastics compatible with the laser beam welding process

Ceramics

Laser welding is also suitable for ceramics such as alumina and zirconia. 

Composites

Carbon fiber-reinforced plastics (CFRPs) and glass fiber-reinforced polymers (GFRP) are compatible with the laser welding technique. 

Your choice from the categories above depends on properties like melting point, thermal conductivity, and ability to melt without charring. Also, reflective materials like stainless steel must be carefully welded because they reflect the laser beam. 

Laser Welding Equipment

A handheld laser welding machine
A handheld laser welding machine

There are many components and types of laser welding machines and this section talks about them and their functions:

Types of Laser Welding Machines

The different types of laser welding machines used in part fabrication and manufacturing can be divided into three categories based on their lasing medium, size, and laser beam delivery. 

Based on Lasing Medium

Based on the lasing medium, laser welding machines are classified into the following: 

  • CO2 Laser Welding Machine 

CO2 laser welding machines have a high energy output but small spot size hence their use in joining thick nonmetals like plastics. They are cheap, fast, and compatible with many materials except stainless steel and titanium due to their reflective surface. 

  • Nd: YAG Laser Welding Machine 

YAG laser uses neodymium-doped yttrium aluminum garnet (Nd: YAG) as a lasing medium which generates a high-powered infrared light with a 1.064micometer wavelength. 

Metals like stainless steel, aluminum, and steel absorb the wavelength better, hence, they are compatible with the Nd:YAG. 

Nd: YAG lasers’ high energy output, good focus, and minimum maintenance increase their use in industries such as automotive and aerospace manufacturing for welding sheet metals. 

  • Fiber Laser Welding Machine 

Fiber lasers are the most common laser welding machine and they use a diode as a lasing medium. They have a higher longevity than CO2 lasers, generates high-quality laser beam, and are used for welding metals and non-metals. 

Based on Size 

Based on the size, the two types of laser welding machines are:

  • Hand-held laser Welding Machine

Hand-held laser welding machines are small, compact, mobile, and accessible making them useful for welding large or complex parts together.

  • Traditional Laser Welding Machine

Traditional laser welding machines are not mobile but are stable and suitable for welding small parts or batch welding. 

Based on laser beam delivery

Based on the laser beam delivery, the two types of laser welding machines are:

  • Continuous Wave Laser 

These lasers emit continuous emitting laser beams which make them form continuous welds down the joint. They are preferred for welding thick parts because they create high-quality and strong welding joints. 

  • Pulsed Lasers

Pulsed lasers emit laser beams at high frequencies and short pulses to make small and controlled welds. They are suitable for parts with complex shapes and dissimilar materials.

Components of the Laser Machines

Every laser welding machine has the following components: 

Laser source

The laser source generates the laser beam using the lasing medium which is then altered by other components such as the laser medium. 

Beam Delivery System 

These include mirrors and lenses that alter the laser beam properties by concentrating, diffusing, or directing it. They are pairable to a CNC system or fixed to a robotic arm.

Cooling System

The cooling system maintains the welding machine’s temperature during the laser welding process leading to reduced heat exposure and guarantees the machine’s longevity.

Workpiece Manipulation System

The workpiece manipulation system holds the workpieces steady, keeping them stable so that the welding procedure is precise. 

Control and Monitoring Systems 

The control and monitoring system manages the laser beam system components and monitors/controls different parameters like laser power and welding speed.

Advantages of Laser Welding

Laser welding has the following advantages over other welding techniques and other non-welding joining mechanisms.

Accuracy

Laser welding is accurate because it allows more control of the laser beam hence its use in creating small and intricate welds and the reduction in heat-affected zones, distortion, and material wastage during welding. 

Lower Thermal Impact

There is less heat dispersed to the surroundings of the metals due to the control of the laser beam leading to a reduced thermal impact and distortion such as bending or stress.

Versatile

Its versatility is centered on its wide material, size, and geometry compatibility making it the most common joining method in many industries. 

High Speed

Laser beam welding is faster than other welding technology leading to increased productivity within a limited time.

Reliability

Laser welding is reliable because of its non-contact nature which reduces defects as a result of mechanical force on the parts. Laser welded joints are strong and durable. 

Limitations of Laser Welding

Laser welding has a few limitations:

High Initial Cost

Laser beam welding machines are more expensive than traditional welding machines which makes them unsuitable for low-volume welding. As a result, small- and medium-scale businesses need to outsource their welding needs to laser welding services. 

Safety concerns

Lasers cause burns and eye injuries when exposed to the skin and eyes which means that manufacturers that use the welding technology must invest their time and effort in ensuring good safety practices.

Weld geometry

Laser welding is the wrong method for joining thick parts or parts with non-fitting edges. You can use it for welding thin and light parts with closed fittings.

Joint preparation

The presence of contaminants, surface oxidation, and gaps in the joints have more effect on the weld quality, unlike traditional welding processes.

Maintenance

Laser welding equipment might require intensive maintenance and setup. As a result, this will increase the operational costs. 

Ensuring a Quality Laser Welding Process

Welding reflective surfaces
Welding reflective surfaces

You can ensure a quality laser welding process by taking note of the following:

Laser power 

Use the right laser power to get the best weld quality. Welding with a high laser power will increase the welding speed and penetration but can cause bad welds when not monitored. On the other hand, low-power lasers are slower but produce quality welds. 

Spot size

You can achieve a small spot size with a higher-quality beam and better-quality focus optics. This will deliver higher laser power but allow more control during the welding process.

Feed/Transverse speed

The feed and transverse speed is the rate and the movement pattern of the laser as it passes over the joint and it can affect the weld quality, the heat-affected zone, and the part distortions. 

A faster feed/transverse speed will reduce weld quality but might increase the heat-affected zone. 

Shielding Gas

Shielding gases prevent oxidation during the welding process. Also, the type and flow rate of shield gas will affect the weld and is chosen based on the type of materials.

Material Thickness

Thick materials require high laser power and slower feed rates. Generally, thick parts are not compatible with the laser welding process because of a lower weld quality.

Joint Design

Joint design can affect the quality of a weld joint. You should ensure that the joints have a close conformance/fit and are accessible.

Applications of Laser Welding in Part Fabrication

Laser welding machine in action
Laser welding machine in action

Laser welding is applicable as a joining technology in the following industries: 

Automotive

Laser welding in the automotive industry is applicable in joining parts and making automotive parts like engines, fuel injectors, etc.

Aerospace

Laser welding in the aerospace industry is common because the industry uses aluminum and it has replaced riveting in making aerospace parts like airframes and security metal detectors. 

Electronics Industry

Laser welding precision makes it a good joining technique for advanced electronic equipment, tiny and advanced electrical sensors, microelectronic components, circuit boards, and transistors.

Jewelry and Watchmaking

Laser welding precision, non-contact welding, and no discoloration increase its use in making and repairing products with complex and fragile designs made from precious metals like gold.

Zintilon Support for Your Custom Laser Service

The high initial cost of laser welding machines can deter businesses from using the process. However, you can get quality custom laser welding services by outsourcing to a reputable service. provider. 

Zintilon is the number one custom laser service provider for business that desires quality. We have standard facilities equipped with advanced technologies and can provide fabrication solutions using laser welding or other welding technology. Contact us today!

Conclusion

Laser welding is a technique with wide industrial acceptance due to its precision, speed, low thermal stress, etc. Being a go-to welding technique for several industries. As a result, this article talks about the process so that manufacturers can understand it before deciding. 

FAQs

Can Laser Welding Be Performed Without Any Additional Shielding Gas?

Using a shielding gas depends on the parts you want to weld. For plastic, ceramics, and composite parts, atmospheric oxidation is small or non-existent. As a result,  you do not need shielding gas. However, metals are susceptible to oxidation and need shielding gas to prevent it.

What are the Common Defects in Laser Welding?

Cracks, porosity, spatter, edge stacking, and sinking problems are common laser welding defects that can alter the joined part’s weld quality.

Is Laser Welding a Contact-Based Process?

No, laser welding is a non-contact process. As a result, there is no mechanical deformation of the two parts. 

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