The machine above is extruding ribbons of dry ice. The ice is at minus 109°C.

It is no secret: manufacturers only make money when their machines are running. This single dynamic influences or limits the amount of time that companies can or will allocate to shutting down production to clean their machines. Cleaning is time-consuming and can be expensive in terms of resources and materials. Many in industry are looking for solutions and processes that will help them to reduce cleaning time and the related costs, while providing consistent, effective maintenance that will allow them to maximize their production time.

Cleaning equipment, from wood and printing presses to packaging and weld lines, are among the messiest and most difficult cleaning jobs. During production in these environments, glues, weld slag, ink and other contaminants get everywhere, and as a result, the machinery often requires lengthy disassembly times even before cleaning can begin. Unless removed, these remnants and contaminants can have a major impact on product quality.

One cleaning method that is gaining acceptance across a variety of industries is dry ice blasting, which uses recycled CO₂ in the form of solid particles that are transported by high-velocity airflow to remove contaminants from surfaces. The cleaning process can help companies to improve product quality, increase production, prolong equipment life, improve worker safety, reduce costs and support environmental initiatives.

Dry ice blast cleaning can be used to clean any part of manufacturing equipment, including electric wiring. By cleaning away ink, grease, coatings and other grime that accumulate during normal operations, dry ice blasting helps to improve product quality, and in some cases, can reduce scrap and help maintain proper machine alignment.

Nozzles used in such cleaning systems come in a variety of shapes and sizes, some for speedy work and others designed to access tight or confined areas. It is a dry process, meaning that it will not wet the surface and is therefore non-conductive, which reduces the risk of rust or possible damage to electrical components and wires.

Applications

The gentleman above is cleaning what appears to be an oven at a wood processing plant. Notice he does not need to dismantle the equipment nor place it into an enclosure. There is very little material accumulating at his feet that will need disposal.

Equipment cleaning is a massive and ongoing endeavor for many industries. Printing with fluid inks at high speeds, for example, creates a mist of ink droplets, which spread onto the color dryer boxes and can clog vent slots. This clogging reduces airflow, and as a result slows printing speed, which halts production and can result in inferior products.

In injection-molding environments, plastic material builds up on the molds, making those molds dirty, blocking small vents and preventing the material from out-gassing. When this happens, end products typically must be scrapped, which amounts to product loss as well as a loss of production time. The contaminant being removed is degraded material.

Automobile manufacturing requires skilled, precision welding. In most automotive welding processes, an epoxy sealer is applied between the automotive panels before they are spot-welded. This sealer is splattered along with welding slag during the welding process. After a period of time, this spatter builds up on the robots' joints and other ancillary equipment. The built-up material makes it difficult to perform regular maintenance and can inhibit the range of motion of the robots. As auto frames pass through the weld lines, they can catch on the slag buildup, causing robots to apply sealant in the wrong location, which can then impair the weld quality. The accumulation of slag and sealant also may require the production line to be shut down to perform extensive and prolonged cleaning.

To combat these buildups, businesses have employed technologies that run the gamut from sandblasting to solvents. Just to remove contamination from molds, companies have tried a variety of cleaning methods, including ultrasonic, Teflon-blasting, solvents and hand scraping. While these processes help clean the molds, the process can require between six and 12 hours to clean a single mold. Dry ice blasting, a relatively new player in this field, can reduce the downtime and improve cleaning.

Productivity, safety and the bottom line

Material building up on a robot arm can reduce its motion and impact product quality. Contaminates are quickly removed to restore motion without disassembly.

Some machines have to be moved, disassembled or both before cleaning can begin. An automotive parts' manufacturer noted that by improving the efficiency of his plant's cleaning process for four to eight molds, the company was able to increase productivity of the machines and the numbers of hours the molds were being used, from seven to 11 hours. The company was able to reduce the cleaning time from a previous range of eight to 12 hours, to less than an hour. Another company noted that on average, one person dry ice blasting can clean a 56-inch press in less than 30 minutes. This echoed testimony from other manufacturers, which claimed cleaning with dry ice blast cleaning systems has reduced cleaning time by as much as 80 percent.

Dry ice blasting also can reduce the risk of damaging equipment. Abrasive cleaning methods often generate heat, and can cause certain substances to become sticky and hard to remove. In contrast, dry ice blasting produces a combination kinetic and thermal shock effect to weaken the contaminants' bonds to the equipment. After hitting the surface, the dry ice particles sublimate and expand. The dry contaminants fall to the floor to be swept up or vacuumed. Because equipment can be cleaned in-place, disassembling and reassembling machinery associated production stoppages are reduced. This blast cleaning also allows manufacturers to conduct frequent preventive maintenance and spot-cleaning without impacting production.

This cleaning method also is safer for operators, reducing unnecessary exposure to harmful solvents and the need to work closely with extremely hot equipment. The cleaning process eliminates the repetitive motions of manually cleaning that can lead to carpal tunnel and operator fatigue.

According to Cold Jet, a manufacturer of dry ice blast cleaning systems, manufacturers across a variety of industries are reporting significant costs savings as a result of changing their manual or media-blasting methods with dry ice blasting. The company's printing customers have reported an average of 58 percent reduction in equipment downtime, from 24 hours to 10 hours. One printing company in Kansas City, Mo., experienced a 93-percent reduction in total cleaning time, from 144 hours to 10 hours. The change resulted in a profit increase of tens of thousands of dollars in only 10 months. In another example, plant managers at a food processing plant estimated that dry ice blast cleaning would save the company roughly $15,000 per year by just using it to clean the cooling tunnel.

The cost savings can come from a variety of areas, reducing the number of employees needed to clean one device, or savings from erstwhile cleaning supplies, such as rags, hand tools and solvents. Most of these companies, however, attributed this reduction to performing cleaning processes while equipment was still online, saving time by not having to disassemble equipment and move it to designated cleaning areas.

Supporting environmental initiatives

Dry ice cleaning can be performed in place without special enclosures.

Dry ice blast cleaning is an environmentally responsible cleaning process that supports the green initiatives of some manufacturers, by eliminating the need for chemical solvents, and because the process' only secondary waste is CO₂. The dry ice does count as a carbon emission, but it's a very small footprint, and almost negligible against other cleaning wastes it can reduce, especially those that add to or complicate the disposal of hazardous waste materials. Dry ice blasting also reduces the need for water in the cleaning process.

Despite the constant pressure to maximize production time, manufacturers must be cognizant of the need for regular maintenance. Unfortunately, it is the demands of the market that often push back scheduled cleaning, which can have both short- and long-term implications. Unless equipment is consistently and properly maintained, production and quality may suffer in the short term, while the machine life may be cut short or plagued with constant repair. Dry ice blast cleaning allows manufacturers to clean faster and more frequently. Most importantly, the ability to clean quickly and in less time allows companies to get back to making products and growing the bottom line. PE