Page 31 - MetalForming Magazine May 2023

Special Section: FABRICATION LASER CUTTING DUST COLLECTION
due to the light weight of these particles.
• Particulate volume: Laser processes are designed for speed—ideal for production— but high-production robotic laser processes also generate more fume than slower manual processes.
In general, laser cutting will produce more fume than laser welding due to vaporization of some base material during the cutting process. Laser welding
also can produce concerning vol- umes of particulate, as the high
heat of the process vaporizes some base metal. Coatings and lubricants can generate large vol- umes of dangerous emissions,
as can filler materials sometimes
used to strengthen the laser welding bond. Some of these emissions may exist in a gas phase, complicating collection efforts.
Uncontrolled laser cutting or weld- ing emissions present dangers to peo- ple, equipment and processes—even if the fume does not produce a visible haze.
Hazards of Inadequate Dust Collection
• Health risks—While laser process- es typically are automated and enclosed, fugitive emissions can create health hazards for employees in the vicinity. The very small fume particles created by laser cutting or welding can be breathed deeply into the lungs. Spe- cific health hazards depend on the materials used but can include asthma and other forms of lung disease, can- cer, kidney disease and neurological damage.
• Equipment damage—Enclosing laser processes will help to protect human workers, but uncontrolled cut- ting or welding fumes inside of the enclosure may cause problems with the laser mechanism itself. Fumes quickly can build within the enclosure, creating a haze that causes refraction of the laser beam. Buildup on the opti- cal lens or in the diaphragm or shutter
The very small fume particles created by laser welding or cutting can be breathed deeply into the lungs. Specific health hazards depend on the materials used but can include asthma and other forms of lung disease, cancer, kidney disease and neurological damage. This makes proper dust and fume collection of utmost important to ensure a safe work environment. For manual laser welding, use a fume arm or backdraft table to pull fumes away from the welder.
mechanisms can lead to costly damage or unexpected shutdowns.
• Product quality—The diffraction of the laser beam—less focused and less precise—caused by excessive dust buildup during cutting and welding can cause part-quality issues. During welding, this results in lower-quality welds that may not meet criteria for weld strength and precision.
• Combustion risk—Given certain conditions, metal or plastic dust cre- ated by welding and cutting may be combustible. While fully oxidized mate- rials are inert, dust created by welding and cutting may contain enough unox- idized material to present a combus- tion risk if allowed to build to danger- ous levels within the enclosure. Flammable dust accumulating on sur- faces also can be ignited by the heat of the laser or by sparks generated by the process, creating a fire hazard. Laser cutting may present a bigger risk than welding due to the larger volume of particulates produced.
Designing an Efficient Dust-Collection System
When designing a dust-collection system for laser cutting or welding, ensure that the system can keep pace
with the volume of emissions produced and capture these emissions in an effi- cient manner. Questions to consider when designing a dust-collection sys- tem for laser-led fabricating processes include:
• What is the volume of fume pro- duced? This will depend on the process, the materials involved, production speeds and production schedules. For laser welding, the use of filler materials or the presence of coatings and lubri- cants will increase the amount of fume produced. For laser cutting, the type of laser, cutting speed and thickness of material all impact the amount of fume produced. Obviously, continuous robotic processes will produce much more dust than intermittent processes.
• How dangerous are the fumes, where are humans exposed, and what are the OSHA Permissible Exposure Limits (PELs) for substances found in the fume? Processes that produce high- ly dangerous emissions, such as hexa- valent chromium or lead oxide, may require a more stringent solution to meet PELs.
• What are the fume characteristics?
• Must the system capture gas-phase emissions as well as particulate?
• How much air must be moved to
www.metalformingmagazine.com MetalForming/May 2023 29