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A cool way to clean

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Features, Operations - Features

Rajesh Wariar, product manager, systems, Karcher Cleaning Systems throws light on surface cleaning techniques and dry ice blasting | 

How and why is parts/surface cleaning essential to many industrial processes?

Many industrial processes warrant the need for parts cleaning prior to surface finishing. Cleaning is also mandatory to protect sensitive components before a necessary repair. Industrial contaminants such as oil, dirt, and grease accumulate during daily operations, affecting the performance of the components or the machinery. This can also lead to safety hazards. Cleaning of the equipment/parts is therefore essential. Moreover, if the parts are clean, it becomes easy to measure and inspect them for defects etc. Cleaning parts also helps to restore their value and improve the working life.

What are the techniques that customers can use when it comes to cleaning parts, and what are the challenges?

There are various technologies available for cleaning, depending on the size of the parts/surface to be cleaned, the type of contamination to be removed, and the medium of cleaning allowed. For example, larger components/equipment/surfaces can be cleaned with high-pressure water jet machines or even sand-blasting machines. Dedicated parts-cleaner machines can clean smaller components efficiently; Dry-ice blasting machines can clean larger, fixed components and sensitive surfaces in the most environmentfriendly manner without adding any secondary contamination.

Every technology has its own limitation – for eg: water-jet cleaning adds the cleaning medium i.e. water, to the contamination – this increases the volume of the contamination that has to be then disposed. Also, metal parts could get rusted soon after cleaning with water, and therefore rust-prevention measures have to be adopted. As regards sand-blasting, it adds sand to the removed contamination, which has to be disposed/collected. The abrasive nature of sand could even result in damage of the surface. Particles of sand could also get embedded onto the cleaned surface, resulting in degradation of the effectiveness of the product. Parts cleaner machines cannot clean parts that are bigger than a prescribed size. Innovative techniques from Karcher, using state-ofthe- art microbiologic technology also provide for excellent cleaning results in an environment-friendly manner without the cost and safety issues of traditional solvent-based cleaners, but here too, the size of the components is limited.

What is the principle of dry ice cleaning?

There are three steps here:

• Cleaning through mechanical energy The dry ice pellets (frozenCO2) are accelerated to over supersonic speed (150 meters/second) by compressed air and they impact the surface.

• Cleaning through thermal energy The cold temperature (-79°C) of the dry ice pellets creates a microthermal shock. Cracking and delaminating of the contaminant occurs. However, the warmer the surface to be cleaned, the better is the thermal effect.

• Cleaning through sublimation The solid pellets enter into these rifts/cracks in the contamination and sublime into gas, increasing their volume by 400 times. In the process, the dirt particles/ contamination get ejected, and thus separated from the surface. Some typical application areas of dry ice blasting are: removing of molds, removing oil and grease, paint, cleaning injection moulds, printing machines, wood restoration, etc.

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