Keys to success in laser welding
What every laser user needs to know
Although a firm grasp of laser physics, metallurgy, tooling and fixturing, weld process parameters, and part strength testing is necessary to implement laser technology in any manufacturing facility, it's also critical to think of other issues that will impact the success of your laser use. Some keys to a successful laser project include involving production personnel early in the process, choosing a laser technology advocate, considering your shop's ambient environment, using trained operators and maintenance personnel, and planning for spare parts and maintenance.
A technician explains the features of an Nd:YAG laser. Involving production personnel early in the process is an important way to ensure the success of a laser project.
Engineers and project managers sometimes reduce the success of a manufacturing process to a few basic mechanical or physical principles.
In laser welding, those principles might involve laser physics, metallurgy, tooling and fixturing, weld process parameters, and part strength testing. Although a firm grasp of these topics is critical to any laser welding project's success, other aspects that you can't measure directly or calculate as easily are just as important.
Some key steps to a successful laser project are involving production personnel early in the process, choosing a laser technology advocate, considering your shop's ambient environment, planning for spare parts and maintenance, and using trained operators and maintenance personnel.
Production Personnel: Involve Them Early
Involving production personnel early in the process is one of the most important ways to guarantee the project's success.
Manufacturing engineers would do well to involve key individuals from the production staff at the onset of any manufacturing project. This isn't simply a pragmatic need to gain philosophical unity, although it should accomplish this if it's done the right way. Instead, you gain value from the years of experience of those who ensure the current manufacturing systems produce parts. These people can offer critical input and suggestions that can transform the ordinary into extraordinary and the mediocre into world-class.
Involvement is the key to ownership, technology transfer, and acceptance. Since the production department ultimately will be responsible for the technology's success, it's important to include them at the very beginning and avoid alienating them accidentally.
Developing a Laser Champion
Another key to success is appointing, guiding, and empowering a laser champion. A champion is critical to consistent production quality and quantity.
Selecting a laser champion probably is the easiest part of the process. When considering the qualifications of your laser champion, you may want to look for someone who:
- Is an engineer, welding or mechanical, or at least has the practical experience of an engineer.
- Has an interest in, or better yet a passion for, laser technology.
- Plans to stay with the company, or is at least committed to passing on his or her knowledge.
- Is teachable and trainable.
- Can teach others and has a desire to share information with others.
Once you have selected a laser champion, the more challenging aspects of the process—guiding and empowering—begin. Guiding or mentoring the champion involves instilling the corporate objectives and vision, as well as providing and supporting the appropriate training.
Many training courses are offered—laser safety, laser welding basics, metallurgy basics, and statistical process control—that can benefit the champion and, ultimately, the success of the laser welding manufacturing process.
The biggest challenge to training is the financial and time cost justification, but training is essential to empowering your laser champion.
Considering the Ambient Environment
Ambient means local, and to consider your ambient environment means much more than simply thinking about temperature and humidity. Foundation stability, atmospheric contamination, and lighting also are important components of your ambient environment. Ask yourself what ambient conditions influence the laser welding manufacturing process, and how you can guard against their negative effects.
In this case, simple things can make a difference. Skipping this step won't save money ultimately. For example, a simple laser enclosure for an Nd:YAG laser system or a new foundation for a CO2 laser welding system can protect your laser technology capital investment.
Consider the following points regarding your shop's ambient environment:
- Temperature. High ambient temperature reduces chiller cooling capacity, and air-cooled chillers must be sized to guarantee proper cooling at the highest anticipated ambient temperature. Ambient temperature also can influence the system's stability and efficiency, because of thermal stress and the accompanying movement and distortion of system components, such as cement slab
foundations, structural members, beam benders, vision system components, and bracing.
- Humidity. Ambient humidity can produce unwanted and even damaging condensation on components that are cooled at a too-low temperature in the hot summer months in humid areas. For example, chiller temperature control and set point must accommodate higher water temperatures for CO2 systems having water-cooled external beam delivery optics.
Humidity also reduces chiller heat transfer, and the chiller must be sized to handle not only higher ambient temperatures, but also higher humidity.
- Foundation stability. Three issues connected to relative motion between critical system components are important to foundation stability:
- Relative motion of foundation segments caused by existing cracks or expansion joints
- Foundation strength to prevent cracks from occurring and causing misalignment
- Shock and vibration isolation
While the first two concerns are especially critical for CO2 systems because of laser beam alignment, the third point is a concern for both CO2 and Nd:YAG systems.
- Atmospheric contamination. Dust, smoke, hydrocarbons, paint fumes, and other contaminants can lurk in factory air. This is why CO2 laser beam delivery systems are purged positively with either nitrogen or clean, dry air. Contamination prevention also is one of the reasons Nd:YAG lasers are most often housed in laser rooms (the other reason
is laser light safety during maintenance procedures).
- Lighting. Proper lighting for maintenance and service probably is one of the most overlooked points concerning the ambient environment. Poor lighting can lead to improper maintenance.
While other considerations are important, the key principle in addressing these concerns starts with asking and answering this question: What ambient conditions can influence the laser welding manufacturing process, and how do I guard against their negative effects?
Design for Maintenance and Service
Engineering reviews often focus on several key issues: plant component and safety specifications, utility requirements, electrical interface, system sequence details, and part production cycle times. Yet your project's success also relies on laser service and maintenance, which aren't always addressed fully.
For example, in CO2 welding systems, laser beam alignment using thermal paper or polycarbonate coupons is a recurring service requirement, but the issues of mirror placement or coupon-holding during beam alignment rarely are addressed. Another example is the water-cooled power meter, which is important to Nd:YAG laser welding. Using the meter to perform a power check at the exit of the laser welding head is a key diagnostic action, and often the water and power connections, required to operate the power meter, are not incorporated into the workstation design.
These maintenance and service items are important but often overlooked. This oversight can result in increased downtime during maintenance and service and cause unsafe situations. Fortunately, you can avoid these problems if you involve laser maintenance and service personnel veterans in your plant in the design reviews. Laser suppliers also can assist with this process.
Choosing Exceptional Operators and Maintenance Personnel
As with the laser champion, selecting the right person for the job is a primary task. Choosing the right operators and maintenance personnel can help guarantee the success of a high-technology process like laser welding.
Beyond selection, training and empowering are critical. Operators need to know how to operate and maintain the equipment in the safest way possible. They also need to understand how all the components of the laser welding system work. More important, they need to recognize when a system isn't performing to its highest possible level.
Maintenance and service personnel need the in-depth working knowledge that comes only with hands-on training and experience. Ideally, you should schedule laser training so it takes place at the laser manufacturer's facility so maintenance and service personnel can dedicate their attention full-time to the training. The timing of the class also is important—it shouldn't be too early or too late. Just before or just after installation generally are the best times. A routine refresher or higher-level training should be conducted on a yearly basis as well. The in-plant laser safety officer and the laser champion should be part of the laser and systems training.
It bears repeating that commitment to training is essential. When training and maintenance are put on the back burner, getting up to speed can consume precious time. The bottom line is that the right people and the right training are important for success.
Don't Spare the Spares
Spare parts are another back-burner item that can endanger your laser project success if you assume a "we'll take care of that later" attitude. Consumables have to be identified and procured, but if they are not properly budgeted for, they can fall through the cracks.
A good on-site inventory can save hundreds of hours of downtime over the life of a laser welding system. With telediagnostics and other remote service capabilities, a well-trained maintenance person can fix a laser problem quickly without an on-site service technician—if he or she has the parts. Waiting until a crisis hits to order spare parts consumes more time and money than ordering in advance. You can avoid counter-to-counter shipping costs and the stress of on-site downtime by having the right spare parts on hand.
When you consider the success of your laser welding manufacturing system, look beyond engineering and physics. Consider the people and components that support the success of your laser project on a day-to-day basis. The right people with the right tools are as critical as the economics, laser physics, mechanical and electrical engineering, tooling, welding, and metallurgy and process control.
David Havrilla is product manager of Nd:YAG lasers at TRUMPF Inc., 47711 Clipper St., Plymouth Township, MI 48170, www.us.trumpf.com.
Want more information?
If you're interested in the strengths and weaknesses of laser processing so you can determine whether or not a laser is the right choice for your cutting application, read "The challenges of laser cutting: Overcoming some common obstacles."
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