It depends on what you’re cleaning. If you’re removing a brittle contaminant such as paint, the process creates a compression tension wave between the coating and the substrate. This wave has enough energy to overcome the bonding strength and literally pop the coating off from the inside out. If you’re removing a malleable or viscous coating such as oil, grease, or wax, the cleaning action is a flushing process similar to high pressure water. When the particles hit, they compress and mushroom out, creating a high velocity snow flow that actually flushes the surface.
People sometimes think it disappears too, but it does not. All cleaning involves the relocation of dirt. When you mop a floor, the dirt moves from the floor to the mop to the water in the bucket. With dry ice, the dirt moves from an undesirable area to an area where you can better deal with it. If it is a dry substance, it generally falls to the floor where it is swept away or vacuumed during normal maintenance. If it is a wet substance like grease, you take a methodical approach similar to hosing down a driveway. You start at one end and guide the grease to the other end where it is vacuumed or squeegeed up.
Once again, it depends on the mass of the object you’re blasting, your dry ice usage rate, and your dwell time. There will be condensation if you cool the substrate below the dewpoint (the dewpoint varies depending on local climate). Of course, if you’re cleaning a hot mold it is rare to have condensation because you seldom cool the mold below the dewpoint. Condensation is not a factor most of the time. When it is, it can be dealt with quite easily. Use of a hot air knife can be highly effective
It is made from liquid carbon dioxide. Dry ice exists as a liquid only under high pressure. When it drops to ambient pressure (the normal pressure that surrounds us), approximately half turns to gas and half turns to solid. The solid, usually in the form of fluffy snow, is then compressed to form dry ice blocks, pellets, or nuggets.
Dry ice blast cleaning originated at Lockheed in the 70’s when a coatings engineer, Calvin Fong, was researching ways to strip paint off aircraft. The technology did not become commercially available until Alpheus bought the license and patents from Lockheed and introduced it to the marketplace in 1987.
The range of cleaning applications for dry ice are phenomenal and is easily demonstrated: core boxes for an automotive manufacturer; delicate wiring in copy machines; conveyors; tyre molds; dry ice blasting shines in cleaning production equipment online, because it eliminates the need for masking, cool down and disassembly. Users minimize downtime which maximizes production efficiency. We have achieved outstanding results cleaning production equipment for foundries, molded rubber producers, food processors, printers, and the semiconductor industry. Dry ice blasting is also widely used in the nuclear industry for decontamination. Anytime waste volume or health risks are a concern, the viability of CO2 should be examined. Because CO2 disappears on impact, it creates no additional waste. Competing processes such as grit blasting or solvents often present disposal problems or health hazards.
Dry ice blasting equipment is used in foundries worldwide to clean core boxes and permanent molds. Not only does dry ice blasting increase production by decreasing downtime, but it also eliminates mold damage, preserving the critical tolerances and greatly extending the life of the expensive tooling.
Virtually every major tyre manufacturer uses dry ice blasting equipment to clean tire molds. We also clean rubber molds for manufacturers of gaskets, O-rings, shoes, and many other products. A good rule of thumb in the rubber industry is, if you can see it, you can clean it with CO2.
CO2 is perfectly suitable for use in this industry because it is food grade quality, the ingredient that provides the carbonation in soft drinks. It is used to clean ovens, conveyor belts, molds, dry mixers, laminators, and packaging equipment
Dry ice Blasting will not etch or profile most surfaces. If you need to clean large quantities of small parts, CO2 is not generally as efficient as other alternatives such as ultrasonics. Because dry ice blasting is primarily a line-of-sight cleaning process, if you can’t see what you need to clean, you probably can’t clean it with dry ice.
Yes, however, the removal rate is dependent on a great many factors including: the underlying surface profile of the substrate; the thickness of the coating; the adhesive bond strength of the coating; and the cohesive strength of the coating (generally a function of age). Generally speaking, if you have concerns with contamination, toxic substances, waste disposal, or substrate damage, dry ice blasting should be considered as a cleaning option.
A methodical approach similar to hosing down a driveway is required if dry ice is to be effective on these and other wet contaminants. You must start at one end and work the grease to the other end where it can pass through a grate or be vacuumed or squeegeed for disposal. Some customers use a paper or plastic backdrop to catch the wet contaminant as it is removed from the substrate.
Dry ice doesn’t dissolve the oil and doesn’t make it disappear so you must have an acceptable way of handling it when it is relocated by the blasting process.
Yes indeed. One of the exciting areas of dry ice use today is in mold remediation and fire restoration. Dry ice blasting will slightly raise the grain on the wood, leaving a finish similar to that of very light sandblasting. If you need a smooth wood finish, dry ice blasting will have to be followed by sanding or some other smoothing method. Because dry ice disappears as it strikes the surface, the only waste that must be disposed of is the removed contaminant and some wood fiber particles.
Yes. Noise is a function of air volume and air velocity. Within the nozzle, the stationary air is sheared by the high velocity air causing turbulence which creates noise. The level can range from 80 – 130 db. Hearing protection is required.
As long as it strikes the surface head on, dry ice does not ricochet because it sublimates (turns into a gas) on impact. As for the contaminant, you usually do not see or feel it as it disbonds and leaves the substrate, however, it is removed with some force which is why eye protection is recommended at all times.
Yes. Any dry air process will generate static electricity and dry ice blasting is no exception. As long as both the blasting unit and the piece you are blasting is properly grounded, you are unlikely to have static discharge problems.
Yes, with proper ventilation. Because CO2 is 40% heavier than air, placement of exhaust vents at or near ground level is recommended when blasting in an enclosed area. In an open shop environment, existing ventilation is sufficient to prevent undue CO2 buildup.