Assessing the situation

To understand whether laser welding is right for a specific application, it’s key to ask the right questions

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Robot 1Compared to conventional spot welding, laser welding allows for more accurate and faster processing along with less heat distortion. The benefits of laser welding, however, only begin there. Remote laser welding offers further advantages, such as faster repositioning between welds, large 3-D working envelopes and the possibility of welding on the fly, a.k.a., welding as the robot is moving.

The advantages impact more than just cycle time and flexibility. Programmable working distances of up to a meter can make light work of hard-to-reach areas.  Additionally, small beam sizes and programmable weld shapes can enable the reduction of excess material needed for overlapping flanges, which in turn, can reduce weight and improve fuel efficiency when applied to automotive manufacturing. Remote laser welding is also much more compact than traditional welding. More welds can be applied in a smaller footprint when compared to any other joining methods.

So clearly, the advantages of laser welding are attractive. But before a fabricator or manufacturer drops their established joining method for laser welding, it’s essential to ask the right questions. Those questions revolve around the motivations to make the switch, the part that will be welded, the necessary welding fixtures and support staff needed to execute the welds, and what to do in the case of equipment failure.

Concerning the motivations behind why laser welding would be chosen over a more conventional method, there can be many drivers. Therefore, it’s important to document them. During the design and engineering process, it’s important to keep the first things first.

Remote laser welding is typically chosen because it’s fast, requires a small amount of floor space and it’s more flexible than conventional methods. Whatever the reason, it’s important to keep it at the forefront when making process-related decisions.

Appropriate parts

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Remote laser welding offers users a myriad of advantages, such as faster repositioning between welds, large 3-D working envelopes and the possibility of welding on the fly.

To better understand if laser welding is appropriate for certain applications, the first question to ask is fairly straightforward: Is the part capable of being laser welded?

The answer to this question needs to begin in the lab. Using a customer’s quality standard or weld specification as a guideline, a fabricator or manufacturer will need to identify certain items through a series of weld trials.

These include a robust set of process parameters; process limitations, such as how much of a gap can the process handle and how much is too much plume suppression; as well as a functional bill of materials or a technical specification for the various equipment that is required in laser welding operations. This equipment includes the laser enclosure, generator, remote laser head, process monitor, power meter and chiller.

Once the process parameters, process limitations and equipment are determined, it’s important to take that information back to engineering and use it as an input to simulation and design. It’s critically important to use the process limitation information to verify gaps and tolerances at this stage, and it’s best to involve all of the teams at this point to ensure nothing is overlooked.   

To continue the conversation about the parts that are most appropriate for laser welding, it’s also key to ask how the part will be controlled. When remote laser welding is discussed, the focus is usually on the high-tech laser equipment and safety and government regulations involved. However, the fixture that holds the parts is every bit as critical to the process as the laser itself.

Clamps should hold the part so that each weld has a repeatable and controlled gap. In some applications, it’s necessary to clamp the surface immediately surrounding the weld to ensure the desired fit-up condition is achieved. These considerations are important to understand before fully adopting laser welding in-house.

Support staff and processes

Typically, a laser system is the most technical piece of equipment within a factory – and it’s one that requires special and unique skill sets. Therefore, it’s important to assess whether the right laser experts and support staff are on board to develop the processes and support the system. Ideally, it is best to have someone on staff that is familiar with lasers that can help coordinate training for a larger group. Once that staff member is identified, training can come in multiple forms.

Laser Specs copy
An example of technical specifications.

First and foremost, laser safety training should be conducted. And it should be carried out by a well-known, established association, such as the Laser Institute of America (LIA). For Class IV lasers, it’s critical that the ANSI Z136.1 specification is followed. As the foremost organization focused on industrial laser operations, the LIA is a great place to get training on the ANSI Z136.1 specification to better understand the hazards associated with an industrial laser.   

For laser generator training, fabricators and manufacturers can work directly with the generator manufacturer. With today’s technology, solid-state lasers, including diode and fiber lasers, may not require hands-on maintenance. Either way, it’s critical to understand what should and should not be worked on.

Laser head training, another important aspect of laser training, can also be coordinated with the laser head manufacturer. As this training is discussed, topics to include should focus on weld positions, process parameters, the laser head cooling system and requirements, cable management, the cover slide monitoring system, configuration of both the software and hardware, and maintenance.

Proper installation, maintenance

In regard to maintenance and repair, equipment failures and weld repairs to be handled also top the list of laser welding considerations. And that’s because, inevitably, equipment failures are going to happen. A remote welding laser system is capable of making a tremendous amount of welds in a very short amount of time, but when there’s a failure, productivity comes to a halt.

To decrease the likelihood of a failure and reduce the impact when a dreaded failure occurs, there are several steps to employ.

Proper installation is one of the most important factors in the successful performance of a system. Therefore, carefully oversee the installation process, ensuring that it is done properly. During installation, key components and what to pay special attention to include the remote laser welding head, the laser generator and the Class I laser booth.

For the remote laser welding head, verify the optics are clean, install new consumables (cover slide), adjust the cover slide monitor, verify the functionality of the pilot light and determine where the focus is. It is also key to determine the offset between the pilot light and laser.

For the laser generator, new users should not only verify that the laser is capable of producing the advertised power, but they should also run the laser at full power for a minimum of the intended process duration to verify it can handle the duty cycle. Inspecting the fiber optic cable ends before installation and verifying that the water temperature is set above the dew point are also important.

As with the welding head and generator, there are also many items to verify during the installation of the Class I laser booth. These include verifying that the booth is light tight, it has the proper signs and labels, its door switches are set properly and the automation doors operate smoothly.

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To better understand if laser welding is appropriate for certain applications, the first question to ask is whether a part is capable of being laser welded. The answer to this question begins in the lab where a fabricator or manufacturer will need to conduct a series of weld trials.

Once installed, ongoing proper use of the equipment will increase longevity and dependability, thereby reducing the probability of a failure. Maintenance, which is critical to minimize the impact of a failure, requires a dedicated maintenance team to visually inspect all cables, hoses and equipment each time maintenance is performed. It’s recommended to monitor the system by taking daily notes or performing daily checks to ensure the system is operating as it should be.

In regard to real-time maintenance, resolve issues as they arise. Allowing a problem to fester will only magnify the impact. As many are aware, laser repairs can get costly quickly.

Therefore, have a backup strategy that the entire team can agree upon. For example, if the laser system welds 100 welds in 60 seconds, it is unlikely that a manual backup is realistic.    

Also, it may be worthwhile to consider ordering laser generators with multiple fiber outputs. Laser generators aren’t capable of supplying laser power to more than one welding head at a time, however, they can be shared between multiple heads at a reduced cycle time.

Finally, take into consideration the number of service technicians the laser related suppliers have when deciding how many and what type of spares to purchase. And have an analog telephone line or network access available for remote diagnosis of laser generators.

Ask for help

remote laser welding
Example of traditional laser stitch welding/spot welding vs. remote laser welding.

In the end, being proactive with the laser welding system, or any system for that matter, is the best line of defense. Adopting this philosophy will make owning and operating a laser system much more successful.

To get assistance with the overall process of bringing laser welding in-house, Comau is a good resource. As a global leader in advanced production systems for automotive component and full body manufacturing as well as turnkey body shops, the company is dedicated to supporting its customers through concept development, engineering, process development, process simulation, production launch and maintenance. With decades of experience under the company’s belt, Comau is able to fully understand the gamut of customer needs and expectations.    

To further support its customers’ needs, Comau has four research and development centers located in the United States, Italy, France and China. And all of its innovation centers are staffed with engineers dedicated to the production of standard products, the introduction of new technologies and, simply put, change.

As market demands force automakers to become more agile in their manufacturing processes, reducing time to market and more flexible joining methods are required. Unsurprisingly, laser welding is being considered as one of the most exciting new joining technologies to adopt in that regard. All it takes is asking right questions and the seeking out the right help to get answers.

Comau LLC

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