Galiaardi uses clean technology lasers to promote welding excellence

High quality welding begins with cleaning any corrosion, contamination, or existing coating on the base metal that may impair weld penetration and integrity. Ensuring that the metal is cleaned correctly from the beginning makes the job easier and eliminates the need to start over to achieve a clean weld.

However, traditional industrial cleaning methods, such as sandblasting, chemical stripping and grinding, are messy, involve expensive consumables, and are time-consuming to prepare and clean up. Regulators such as the EPA and OSHA are also scrutinizing these methods for potential harm to technicians and the environment.

Now, a better alternative for industrial engineers and managers seeking to ensure operational efficiency and cost effective manufacturing is to use systems based on industrial grade precision lasers. The laser system can use a high energy laser beam to remove contaminants, rust, residue and paint from the weld surface, leaving the substrate unaffected. Preparation and cleanup times are minimal, and low-maintenance equipment can last for years.

Vincent Galiardi, owner of Galiaardi Laser Clean, a surface cleaning operator based in St. Charles County, Missouri, notes that many people are surprised to find that cleantech lasers are the most cost effective, efficient and safest method of industrial surface treatment.

For welding applications, Galiaardi said: "Pre-welding laser technology can effectively clean the surface, so there is no contamination [to interfere with welding]. After welding, the laser can remove discoloration caused by oxidation, which helps to improve the stainless steel weld.

Because of their effectiveness in treating metal surfaces, industrial laser systems are increasingly used for welding applications. A technician can use a mobile handheld device, or the system can be integrated into an automated online processing line. With significant advantages in safety and efficiency, laser cleaning is expected to disrupt the welding surface treatment market.

Address traditional cleaning limitations

Prior to welding, any impurities on the surface of the base metal, such as dirt, residue, corrosion, abrasion or old coating, will affect the effectiveness of the weld. When small metal particles travel through the air or are loosely attached to the weld area, any contaminants can interfere with the process, cause resistance or cause welding spatter. Contamination of the weld surface can lead to pores or trapped gas bubbles in the finished weld, weakening its mechanical properties and requiring rework.

Cleaning after welding is also necessary, especially for stainless steel. Stainless steel provides natural corrosion protection through its ability to "passivate" itself if the environment provides sufficient oxygen to repair a surface film composed of chromium oxide. However, welding can cause "thermal tint" -- the discoloured, thickened surface of stainless steel around the weld in the heat-affected zone -- which affects corrosion resistance. Removal of heat tinted top layers is necessary to restore the stainless steel to full corrosion resistance and aesthetic value.

Sandblasting involves forcing a stream of abrasive particles onto a surface, usually using compressed air or steam. The silica sand used in sandblasting often breaks into fine particles and becomes airborne, which can cause serious or fatal respiratory illness. Sandblasting can also be time-consuming to clean up, as the sand is basically scattered everywhere, although it is generally considered a "quick" method of cleaning.

Chemical stripping often uses harsh, even toxic chemicals or pastes to strip welds and metal-based objects of contaminants, rust, and paint onto exposed metal. For the operator, however, exposure to corrosive acids and toxic chemical fumes is inherently dangerous. The process can also be very time consuming to prepare, achieve the required level of cleanliness and dispose of waste. In addition, handling toxic chemicals is costly and heavily regulated.

An Angle grinder removes large contaminants, and a sanding tray removes rust, paint, and grime. However, the erosive nature of grinding can quickly destroy the metal to be welded if care is not taken. Disc grinders basically just peel away the rust, and it travels through the air and makes a mess. Grinders can also be dangerous because sparks or debris can shoot off the wheels or catch clothing.

Laser cleaning improves safety and operational efficiency

For industrial engineers and managers, laser-based systems offer significant advantages over traditional methods, including ease of use, with operators simply pointing and clicking a high-energy laser beam at a surface. The substrate is not affected by the laser and the system does not produce any messes or by-products. The method is environmentally friendly, energy efficient and can complete the job in half the time of traditional methods, including preparation and cleanup.

"Laser cleaning is just as fast as other methods in removing rust or old coatings, but there is not the same amount of cleaning," Galiardi said. "When we treat the surface with a laser, any smoke or particles that fall off are extracted into the HEPA filter and the job is done. No media [sand, chemicals] need to be replenished or cleaned.

He noted that Galiaardi Laser Clean uses Laser systems manufactured by Laser Photonics, Orlando, Fla., a supplier of patented industrial-grade Cleantech laser systems for cleaning and surface conditioning. American-made systems can be used either as mobile stand-alone units or integrated into production lines.

Laser systems are available in portable and stationary models with power ranges from 50 to 3,000 watts (a 4,000-watt version is under development) and chamber sizes ranging from 3'x 3' to 6'x 12'. The system can also be installed in a cabinet on a production line or operated by a robotic arm.

According to Galiardi, laser treatment of metal surfaces can be used to simplify the welding cleaning process, even in relatively remote areas of the site.

He recounted how he used a portable clean tech laser system for a welding project on the Grand Canyon's iconic pedestrian bridge. The pedestrian bridge extends to the rim of the Grand Canyon, providing thousands of feet of clear views of the canyon floor below.

"When I was working on a pedestrian bridge at the Grand Canyon, I used a laser system to remove the paint [from the pedestrian bridge welds] so that the welds could be nondestructive tested [before being repainted]. "The system's portability makes it quick and easy to use in the field without the cleanup or safety issues associated with traditional cleaning processes," Galiardi said.

For industrial engineers, managers and technicians, clean laser technology is now an environmentally friendly alternative to sandblasting, chemical stripping and grinding for pre - and post-weld surface cleaning. This method is safer for technicians and highly adaptable to a wide range of welding applications.

Source: Laser Net