When given the choice between conventional and unconventional, most folks take the conventional route. The latter feels too risky – even when the conventional way is costly or dangerous.
Unfortunately, this human tendency is alive and well in the world of metal cleaning and surface preparation. Right now, somewhere, a fabricator or manufacturer is running parts through an abrasive blasting or chemical cleaning process when they could be leveraging laser ablation technology.
Abrasive blasting and chemical cleaning both come with a lot of costs and a lot of hazards. They require complex, expensive material handling and disposal processes and generate contaminates in the form of fumes and dust that are harmful to employees. Higher-than-normal medical claims, low retention rates and, in turn, additional costs for hiring and retraining aren’t uncommon.
“Bead blasting in general is dirty,” says Dmitri Novikov, director of business development at IPG Photonics Corp. “The very fine dust is impossible to contain even with a dedicated enclosure; fine particles are flying everywhere, covering entire areas in dust. The people working in these positions often get hurt by flying debris even when they’re wearing all of the appropriate PPE equipment and everything seems to be contained. The work is physical and difficult.”
To add insult to actual potential injury, the conventional methods aren’t precise – it’s impossible to put part of a component into a blast enclosure, so the entire part will need to be put through the process, even if only one portion of it needs to be cleaned. And, all of that fine debris finds its way into the cracks and crevices of parts, causing quality issues with powder coating and other processes.
Modern method
Laser ablation isn’t a new concept, so it may seem surprising to some that it could be considered unconventional, but abrasive blasting or chemical cleaning processes came first, and manufacturers have become complacent to the risks and costs involved. This, too, is just common human nature; we are creatures of habit.
“Everybody knew about the theoretical cleaning possibilities with laser ablation, but in the past, it was a bit of a problem because of the lack of power control,” Novikov says. “With fiber lasers, however, the fine-tuning of the power is so good that you can ensure that once you develop a process, it can be repeatable.”
When fiber lasers came onto the scene, all types of laser processing were revolutionized, including ablation. Today, laser cleaning is made possible thanks to recent fiber laser advancements – specifically, precise parameter control that can target specific part areas and tuning that takes the varying thresholds of coatings and underlying substrates into account. This tight control of the beam also means that underlying parts and fixtures won’t be damaged. Furthermore, modern laser ablation relies on a nanosecond laser, which offers a short pulse duration.
“The nanosecond laser is the workhorse of laser ablation,” Novikov says. “The shorter the pulse duration, the less damage you create on the surface.”
In terms of safety, ablation is non-contact, meaning there’s no physical media required and, therefore, no deafening noise, no potential projectiles and no fine dust. As an added bonus, parts that have been cleaned using laser ablation are immediately ready for downstream processes. There’s no need for drying or removing errant dust.
Productive products
Laser ablation is made possible through the use of three standard IPG products: LightWELD XC, LightWELD XR and Ablation LaserCell, a turnkey robotic laser ablation system. The turnkey laser ablation system is a standard, but configurable automated ablation cell ideal for aerospace, automotive and other high production manufacturing operations. The LightWELD XC and LightWELD XR are the most recent additions to IPG’s LightWELD series of handheld manual fiber laser welding systems.
“LightWELD XC and the more powerful LightWELD XR have the addition of an ablation or cleaning regime,” Novikov says. “Traditional, manual welding requires a preparatory step – making sure that there is no debris, no oils, nothing fishy in the weld pool – which has to be carried out with a separate tool or product. But with LightWELD XC and LightWELD XR, the cleaning regime is integrated into the same welding tool, so you can clean the metal surface, switch to the welding regime and start welding; all in one system.”
For context, the original LightWELD system, which is just as portable as a normal, non-laser welding machine, takes manual welding to the next level. Basically, it works just like a traditional welder. It can be plugged into a 220-outlet and can be used anywhere – on a construction site, in a fabrication shop or even in a garage, provided that a laser safe working area can be accommodated.
“The only difference is that the speed of welding is much higher because of the concentrated laser light,” Novikov says. “And, the ease of welding is very good because even people who never, ever welded in their life can pick up this technique in like half an hour. It’s the future of manual welding.”
Conversely, IPG’s Ablation LaserCell is dedicated solely to the ablation process and in an automated manner. The fully automated Class 1 laser system provides cleaning, coating removal and surface roughness modification for manufacturing, refurbishment and repair applications.
“In terms of the reconfiguration options, that often relates to how you place the parts inside the cell,” Novikov explains. “You can, for example, have a conveyor belt that moves parts into the cell where a robot picks up the part and positions or rotates it under the laser. Alternatively, the laser can be mounted on the robot arm, which then moves around the part. This is typically employed for big parts to ensure that we can hit all of the required areas of the part.”
Relevant applications include cleaning of residue buildup in molding applications and fixtures and tooling used in spray booth applications. The Ablation LaserCell is also used for the removal of thermal barrier coatings in power generation applications and for pre-weld surface preparation to remove contaminants and oxides. Post-weld cleaning is, of course, also a major application for the ablation process. Anyone that requires a repeatable cleaning process will benefit, but aerospace and automotive industries have perhaps the highest potential for the technology.
“Currently, automakers have to remove paint from wheels, which they sometimes receive pre-painted,” Novikov says. “The current technology is hot acid bath, but that method will start destroying the base material if you do it more than two times.
“Another major application for automakers is the manufacturing of battery parts,” he adds. “When you weld battery components together, it’s critical to ensure that there are no electrolytes on the surface. That’s where laser ablation comes into play. If you don’t clean the dust, oil and electrolytes from the surface before welding, it can create a catastrophic event for the final battery product. The number of batteries that they’re welding is enormous, so the cleaning process needs to be incredibly productive.”
East of use
According to Novikov, getting up and running with the LightWELD products is fast and easy. The handheld systems comes with a set of programs that users can choose from for a certain material at a certain thickness. Everything is pre-set, but in the case of exotic materials, for example, users can set their own parameters.
Similarly, the Ablation LaserCell is equipped with a full process library for various applications, making programming incredibly straightforward. Because it’s an automated cell, the robot will also need to be programmed. Once completed, however, the process will be highly repeatable. And, for oddly shaped parts, a vision system can also speed up the process.
“Before cleaning, you would scan the part, which creates a model of the part, and then, using common software, you can create a cleaning pass,” Novikov says. “If you don’t necessarily need to clean the entire part, that, too, can be easily programmed. It’s important to note, however, that this isn’t possible or relevant with LightWELD.”
In addition to being a safe, easy and precise technology, the laser ablation process is also a green technology. It produces significantly less waste than other techniques, and there’s no need for expensive or cumbersome disposal.
Since the handheld LightWELD systems and the Ablation LaserCell are all relatively new products at IPG, Novikov says IPG’s training centers, demo rooms and partners can answer questions and provide demonstrations.
