What is a Keyhole in Welding?

In certain welding jobs, you require higher amounts of power density and heat penetration to achieve the desired result. This is not easy considering the attention and precision that manual welding jobs require. Most welders utilize an automated technique known as the keyhole heating method for such detail-oriented tasks. If you want to know more about what keyhole welding is, then keep on reading.

What is Keyhole Welding?

The keyhole welding method is a type of laser welding. It is used for butt joints or open groove weld joints. In this technique, a gap is maintained between the two pieces that are meant to be weld together. When exposed to heat, both sides of the plates burn away to form a weld pool.

In keyhole welding, the metal doesn’t only melt; it vaporizes. The vaporizing metal creates gas that pushes the metal outward, creating a keyhole-like shape. The heat is then directed down the plates a few inches away. Doing so gets the hole to travel with the heat. The molten metal then fills in the hole, which then forms the weld bead.

Care should be taken to ensure that the keyhole doesn’t grow too large. If it does, then the weld puddle will fall out of the opening. In case it does become too large, then stop welding immediately. Allow the plate to cool before you start the process again.

As long as the laser power is strong enough, and the travel speed is not too high, the hole will remain open. Applying excessive heat, using the wrong rod angle, or staying too long in the puddle can create problems in the weld joint.

Advantages of Laser Keyhole Welding

Resistance spot welding can easily replace laser keyhole welding in a lot of procedures. However, there are certain benefits to the latter method that make it highly beneficial.

1. Increased Efficiency

Resistance spot welding is a time-consuming, manual process, and it may provide inconsistent results. Laser keyhole welding is mostly an automated procedure. When you use this technique, you end up saving a lot of time. Because the process is machine-controlled, you also end up producing consistent and quality welds.

2. Suitable for a Broader Range of Metals

Different physical, chemical, and mechanical properties of different metals dictate which process is ideal when it comes to welding different metals. Not all metals are easy to penetrate through. For alloys with high resistance, the keyhole technique proves better as it vaporizes the metal, making the welding process more manageable. The powerful laser beam utilized in this method diversifies its applications.

3. Better Control

You need to apply pressure in resistance spot welding, which can cause indentation. It also dictates the penetration levels that can be achieved using this method. In laser keyhole welding, the laser beam controls the penetration levels. Because the process is automated, there isn’t a lot of manual power or any additional pressure needed to create a weld.

Keyhole welding also eliminates the possibility of indentation on the metals. It saves the welder the grinding and damage repair costs while also saving time.

4. Faster results

Keyhole welding is ideal for thicker metals as it provides greater efficiency and deeper penetration with ease. It is also beneficial for use on thinner metals as it speeds up the process.

Because the process is automated, it is consistent and predictable. It allows the welder to produce high quality finished product welding and reduces work time by speeding up the process by three to four times the average speed.

It also saves the time spent on finishing manually produced welds.


The cost of setting up laser welding is high. It requires the purchase of automated machinery, such as a robot welding system. For smaller enterprises with not enough funds to back such purchases, this may be a tough investment to make, especially if they do not have repeatable parts.

Tools, fixtures, and other required materials for this process are essential to laser welding success. The two workpieces to be welded must be firmly joined together without gaps. To do so, you need specific equipment, and this also adds a significant amount to the investment cost. Appropriate joints, materials, and proper assembly lines are essential to produce high-quality laser welds

You can only unleash and utilize the full potential of laser welding for highly repetitive production processes. The substantial funding laser welding requires during setup demands that it be used to its full capacity to earn a good return on investment. If you have a small business that does not require the constant use of this machinery, then we suggest that you do not waste your money on this process.

Before you decide to transform your production process, consider these factors. If your cost-benefit analysis isn’t positive, then don’t opt for this change. If you are not facing a work backlog due to slow production, then do not choose this process. If you are dealing with thinner metals and joints that are easy to deal with, then you do not need to fork out such a massive sum of money. For thinner metals, you can also look at the conduction method for welding.

Conduction Welding

In the heat conduction welding method, the depth of the penetration is relatively low. It is controlled by creating small pulses along the edge of the weld joints. The joint metals melt and merge into one another. Once they cool, they form a smooth and pore-free weld seam.

The heat is conducted using the pulse technique. The longer the pulse, the greater the heat conducted. By using this method, we create wider welds as compared to the deeper welds created by keyhole welding.

The heat deployed in this method is pretty high but not high enough to vaporize the metal. The conduction method is ideal for use on thinner metals. It gives you more extensive surface penetration that provides smooth final results. The conduction welding technique is used when welds do not require high weld strength.

Application of the Conduction Welding Technique


Stainless steel sinks are a staple in a lot of kitchens, and so are stainless steel countertops. They may look seamless, but they aren’t. They have been welded together using the conduction method.

Metal Bellows

Metal bellows are elastic vessels that allow pipes, vacuum pumps, or measuring instruments to expand and contract. Bellows are quite hard to create as they require even and continuous heat input. These thin, flexible membranes form an essential part of most infrastructures, and they are created using the conduction welding technique.

The conduction method and the keyhole method are the two types of laser welding techniques. Laser welding is one of the most technologically advanced forms of welding.

What is Laser Welding?

Laser welding utilizes a highly concentrated beam of light on material. The material absorbs the energy from the light. The particles gain momentum, and eventually, the material melts. By concentrating the light onto two different metals, we can have them melt and amalgamate into one, producing a joint.

Laser welding produces four basic types of joints:

  • Edge Flange Weld
  • Filler Lap Weld
  • Butt Weld
  • Overlap Weld

In most laser weld process, CO2 gas is used as the shield gas to protect the molten metal from the atmosphere. With the beam, a nozzle is simultaneously directed at the weld metals to ensure maximum protection.

If you intend to skip out on the cutting or shield gas, then you may have to invest in a control room. Without shield gas, laser welding is only possible in a vacuum environment, which is very costly to set up. Because laser welding is a very high tech process, it requires significant investment, but it does have its advantages.

Advantages of Laser Welding

  • The welding process can be automated using a CAD/CAM setup
  • No electrode is used in the process
  • Tools and equipment do not wear out
  • Laser welding is highly specific in targeting
  • High-quality welds are obtained

Laser welding can be used in combination with other welding techniques such as arc welding. Often lasers are combines with Metal Inert Gas, tungsten Inert Gas, or Submerged arc welding procedures. The resultant weld contains the benefits of both arc welding and laser welding.

By using either laser keyhole welding or conduction welding method, you can save time, produce smoother, more durable welds faster, and increase overall production efficiency.

Related Questions

Is keyhole welding feasible?

Keyhole welding is feasible if you have the funds to invest in this process, and you have to weld thick metals constantly. If you don’t need to weld such metals and don’t require the heat produced by keyhole welding, then this technique is not for you.

What makes a laser weld better than other welds?

Laser welds have very deep, penetrating joints. They also have improved tolerance to joint fit-up. Other than that, laser welds don’t suffer from negative effects like internal porosity and cracking.