Managing automated weld line cleaning with dry ice

Automated weld lines are difficult to clean and maintain. Dry ice cleaning eliminates the negative effects of traditional cleaning methods

Robotic arm cleaning with dry ice.

Automated weld lines are difficult to clean and maintain. The most common issue is weld slag, spatter, resin, soot, grease, and other material building up on the robot joints, jigs, and ancillary equipment. This buildup makes it difficult to perform regular maintenance on the equipment, and the range of motion of the robots is reduced.

Buildups cause misalignment and can prevent the proximity switch from firing in the appropriate spot. When this happens, the robot stops welding or welds incorrectly, creating scrap and causing equipment failure. The production line may even need to be shut down to remedy problems caused by this excess accumulation, multiplying preventable production costs.

Also, during traditional preventive maintenance, skilled electricians and mechanics spend a disproportionate amount of time cleaning troubled areas rather than focusing on items requiring repair.

Traditional cleaning methods are time-consuming, labour-intensive, costly, and often not fully effective. Manual scraping and scrubbing with wire brushes, water, or chemicals can consume many hours and extend downtime, damage equipment, shorten asset life, and reduce asset use rates. It also can be potentially harmful to employees.

Dry ice cleaning eliminates the negative effects of traditional cleaning methods and enables employees to quickly clean weld line production equipment in place. It allows for complete online cleaning, a reduced scrap rate, elimination of equipment damage, and maximized tooling life.

Dry Ice Cleaning Explained

Dry ice cleaning is similar in concept to sand, bead, and soda blasting in that it cleans surfaces using a media accelerated in a pressurized air stream. It differs in that it uses non-abrasive solid CO2 pellets or CO2 microparticles accelerated to high velocities to impinge on the surface and clean it. The particles sublimate (turn from solid to gas) upon impact, lifting dirt and contaminants off the underlying substrate without damage and without leaving any residue behind.

The unique characteristics of dry ice make it an effective media for cleaning production equipment on an automated weld line.

No secondary waste: Cleaning with dry ice enhances sustainability efforts. It sublimates upon impact with the surface being cleaned, which means no secondary waste, residue, and moisture are being generated. This eliminates the added costs of extra cleanup; disposal of secondary waste streams, and additional cleaning preparation, such as masking delicate sensors or wrapping electronic components prior to cleaning.

Using dry ice as a cleaning media is environmentally responsible and does not add CO2 to the atmosphere. The process recycles existing CO2 by phase-changing it from gas to liquid to solid to gas.

Weld line before dry ice cleaning.

The cleaning process does not use water, which allows equipment to be cleaned while online and still operating. Because dry ice is non-conductive, it allows for electrical equipment to be safely cleaned.

Non-abrasive: Dry ice is a powerful cleaner, but because it is a very soft medium, it can clean even sensitive electronic equipment or around welding tips without etching, profiling, or changing surface dimensions.

Many production facilities are adopting a "no-contact cleaning" process in their maintenance programs. This is to prevent costly damage to equipment and tooling. Dry ice accomplishes this initiative because the dry ice particles are blasted onto the surface being cleaned in a non-abrasive way and then sublimate, eliminating any contact.

Non-toxic: Dry ice is a food-grade medium that is EPA, FDA, and USDA approved. It is colourless, tasteless, odourless, and non-toxic. It can replace environmentally harmful cleaning chemicals and eliminate worker exposure to these cleaning agents. It also does not produce any toxic waste that would require disposal.

Dry ice cleaning machines are mobile and can be rolled up to the robot or other equipment being cleaned to maximize in-situ cleaning capability. Various hoses and nozzles can also be fitted to ensure that no cleaning job is out of reach.

Benefits

This cleaning method can lead to cost savings, improved productivity and product quality, extended equipment life, and improved worker safety.

Reduced costs: This cleaning method reduces labour costs because it can be done by one person and in significantly less time than conventional manual labour.

Improved productivity: It helps reduce shutdown times and enables more cleaning during a scheduled shutdown, as equipment can be cleaned while hot and online without disassembly and reassembly. By cleaning equipment in less time, facilities are able to get more production cycles from existing equipment. Preventive maintenance or spot cleaning can also be done more frequently without impacting production. The entire weld line can be cleaned during a scheduled maintenance shutdown.

Improved product quality: By cleaning away slag, spatter, resin, and other grime that accumulates during normal operations, dry ice helps improve product quality, reduce scrap, and maintain proper machine alignment.

Weld line showing section clean with dry ice.

Prolonged equipment life: This form of cleaning is a dry process that is non-abrasive and non-conductive, so it will not damage equipment and is safe for most surfaces, including electrical components. It will not etch or nick the copper and brass fittings of the robot and jigs like traditional methods can.

It can also be used to clean around sensitive equipment, such as proximity sensors and photoeyes, without damaging them.

Improved worker safety: The process eliminates employee exposure to toxic cleaning materials. It also eliminates repetitive motions of hand cleaning or scrubbing, chiseling, or activities that require pounding, sanding, or scraping.

Dry Ice in Action

An industrial service provider based in Lexington, Ky., is a good example of how this cleaning method can help a facility. This company provides critical process cleaning, maintenance, and support services to the automotive manufacturing industry. Automotive facilities often contract with the company to clean and maintain their automated weld line robots and equipment. The company uses dry ice cleaning on these projects and has experienced large cost and time savings.

Before implementing dry ice cleaning, the company manually performed the cleaning with hammers and chisels. Since implementing dry ice, the company has reduced labour hours per robot from 7.2 to 0.5 and reduced overall labour time by nearly 70 per cent. They also reduced cleaning costs by up to 60 per cent and reported an annual savings of more than US$150,000 (for 38 robot cleanings per week) over the hammer and chisel method. The company experienced a quick ROI on its dry ice cleaning machine of 344 robot cleanings, or 2.3 months.

Tyson Marlowe is director, global training and development, Cold Jet, 455 Wards Corner Road, Loveland, Ohio, 45140, 513-831-3211, www.coldjet.com.

Images courtesy of Cold Jet.