Clean it up
- Category: Maintenance
- Created: 2018-04-03
Laser cleaning equipment gives fabricators clean, contaminate-free parts and surfaces
by Susan Woods, managing editor
Plenty of fabricators have a need for parts cleaning equipment. To get the cleaning results they want, they need the right equipment. One consideration is laser cleaning -- a versatile process that can be adapted to many different kinds of contaminants, substrates and applications in a range of industries.
Laser cleaning involves removing contaminants, residues, rust or other impurities, paint or coating from the surface of a material using laser irradiation with a focused laser beam. It’s an economically and environmentally friendly process. Because it has no effect on the base material, laser cleaning is often used to prepare surfaces for other processes, such as painting and welding.
Where applicable, laser cleaning can replace conventional abrasive and chemical cleaning processes. A major benefit is that laser cleaning uses no consumables and creates little to no waste, making it environmentally friendly. Any waste that is created is in the form of dust particles that can be easily collected and removed. Both traditional approaches require a great number of consumables and create huge amounts of waste that have a negative environmental impact.
Another benefit of laser cleaning versus conventional methods is it is a non-contact process; there is no wear or damage to the base materials.
On the other hand, the abrasive blasting process can damage the base material and typically cannot be used on delicate surfaces.
“With abrasives blasting, you change the surface profile of the part, depending on the media,” says Nick Davidson, business development director, Adapt Laser Systems LLC. “People should be aware, however, that a rough surface isn’t always necessary. The specs typically are written for blasting, and the only way to measure a blasting process is surface roughness. There are some parts that need a rough surface for the coating to adhere to. But in most cases, the reality is all they need is to remove the contaminants. With a laser, they can do it.”
And they can do it with ease. Laser cleaning can be highly automated, and in addition to productivity and cost benefits, automation also allows for an element of safety by involving the operator less.
Much of the cleaning with chemical solvents, on the other hand, is at a low level of automation, meaning the operator is heavily involved. This can also be a safety hazard as the chemicals produce hazardous fumes that require the operator to wear protective equipment. Using chemical solvents also produces high amounts of potentially hazardous waste that requires costly disposal.
And although it’s capable of a medium to high level of automation, the abrasives blasting process also creates significant amounts of waste that must be disposed of.
Beyond disposal requirements, laser cleaning offers additional benefits, such as increased precision and improvements in process speed. It also offers a high level of control; the cleaning can be applied to very specific areas.
“Another primary benefit is that it’s hard to beat the level of cleanliness the laser offers as well as the consistency of the cleanliness,” Davidson says. “Any kind of manual process with chemicals or abrasives is subject to the variability of the operator. Abrasive blasting is relatively consistent but does not clean as thoroughly as the laser.”
So while abrasives and chemical cleaners will always have a place in industry, Davidson notes that for laser cleaning to be a consideration for a good business case, the user should have one or more of three requirements: high-quality cleaning, environmentally friendly and safety, or no alterations to the base material.
The process works
The technology behind laser cleaning is known as laser ablation where the laser energy is focused through the emitting laser beam and absorbed by the surface layer. The faster the absorption factor, the faster the process. The energy results in sublimation of the contaminant or coating, converting the solids into gas.
For cleaning, the laser beam is pulsed, although laser power, wavelength and other parameters such as pulse speed may differ. The pulsed laser technology is more efficient and provides a faster removal speed than a continuous laser beam.
“The power requirement is different for laser cutting versus cleaning,” Davidson says. “With a cutting laser, the beam is constantly being emitted, it’s continuous energy. Our laser pulses on the nanosecond level. The laser source itself may only be 300 W of power, but we have an energy per pulse in the kilowatts of power spread over a set area depending on the laser optics. Putting the same energy in a much shorter pulse creates more power per pulse.”
While strong enough to completely vaporize the surface material, there is no risk to the base material from the laser beam. “When you hit the base metal, the laser literally reflects off of the metal and doesn’t damage it,” Davidson says.
While most of the removed material is vaporized, the remainder may be suctioned away as particle dust and collected in a filtration system.
“Our optics feature integrated suction in our optical system,” Davidson says. “The optics pull any dust away to keep it out of the air and capture it in our filter system designed for laser ablation. While the dust particles may or may not be harmful, as a best practice, we recommend collecting it to keep it from accumulating on the optical lens. That is a secondary benefit of using the filtering unit.”
The right application
While the laser ablation process is essentially the same for all laser cleaning systems, it’s the implementation of the products that differentiates manufacturers. Adapt Laser Systems has focused solely on providing laser cleaning solutions for industrial applications for more than 15 years as the service and support partner for CleanLaser in North America.
The company offers fiber-coupled, compact, mobile or stationary laser cleaning units with 20 W to 1,000 W of laser power for a range of applications using a handheld, enclosed cell or automated system, depending on the operation setup and part size.
“The model and power level are application dependent,” Davidson says. “For a small area or part, you could use one of our lower power lasers in a cell or as a handheld. For larger areas or where quick cleaning is required, a mid- to high-power laser might be appropriate in one of our larger cells. For applications that aren’t repeatable, any of our handheld systems would work well. Additionally, we always have the option to incorporate automated optics on the end of a robot into your production line.”
While the enclosed systems fit the Class 1 specification, the handheld and automated versions are Class 4 (the most dangerous) unless the laser system is placed in a Class 1 environment.
“Safety is important and something we focus on with customers,” he says. “Everyone that operates a Class 4 laser must wear special eyewear designed for the wavelength and beam characteristics of the laser. Everyone within optical hazard distance must also wear the eyewear unless you can create a ‘Class 1 area by administration.’ We set up curtains similar to welding curtains, beacons and other warning signals that meets this requirement.”
In addition to industrial manufacturing environments, laser cleaning can also be applied to the manual cleaning of larger objects, such as rust removal on bridges or contaminant removal from aircraft. Safety concerns still need to be addressed, of course, and it’s important to note that the laser cannot operate correctly in extreme cold or heat.
No matter the application, laser cleaning can be considered a viable option. However, “laser cleaning isn’t for everyone,” Davidson concludes. “Your application needs to fit in one of the three main business cases I mentioned: quality, environment or safety, and damage-free parts.”