Solvent degreasing is a process used to prepare a part for further operations such as electroplating or painting. Typically it uses

petroleum Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crud ...

chlorine Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine i ...

dry ice Dry ice is the solid form of carbon dioxide. It is commonly used for temporary refrigeration as CO2 does not have a liquid state at normal atmospheric pressure and sublimates directly from the solid state to the gas state. It is used primarily ...

or alcohol based

solvent A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...

s to dissolve the machining fluids and other contaminants that might be on the part.

Process

To begin with, a cleaning agent is applied directly to the surface by spraying, brushing, blasting or wiping. This process removes oil, grease, dirt, loose particles, and any other contaminants that may exist on the surface of the material. Characteristics include: cleans almost all electronic assemblies, electrical components, and almost all metals. Parts are usually dried at an elevated temperature, however usually not below room temperature. However if you're cleaning by dry ice blasting objects are left dry and clean. Almost any size or shape of a part can be cleaned.

Spraying

The most common cold solvent operation, this is usually used in small maintenance degreasers using a petroleum or mineral solvent. Usually to remove the bulk of the material, and prepare it for the cleaning tank. Although if the part does not need to be perfectly clean, then the operation can be ended after spraying. Spraying can also be used as a prequel other degreasing operations such as

vapor degreasing Vapor degreasing is a surface finishing process. It involves solvents in vapor form to cleanse the workpiece in preparation for further finishing operations. Process The acting principle behind the vapor degreaser process is that the solvents wil ...

which gives a better clean.

Immersion

The part is immersed in a tank of solvent and usually agitated like a

washing machine A washing machine (laundry machine, clothes washer, washer, or simply wash) is a home appliance used to wash laundry. The term is mostly applied to machines that use water as opposed to dry cleaning (which uses alternative cleaning fluids and ...

for clothes to get all of the contaminant off. It is then hung on a rack over the tank to allow drying.US EPA. (1995). Solvent Degreasing. Available: http://www.epa.gov/ttn/chief/ap42/ch04/final/c4s06.pdf . Last accessed 19 April 2008. This is not to be confused with

pickling Pickling is the process of preserving or extending the shelf life of food by either anaerobic fermentation in brine or immersion in vinegar. The pickling procedure typically affects the food's texture and flavor. The resulting food is cal ...

, during which the part would be soaked in the bath for an extended period of time. This operation covers a relatively short period and doesn't clean as deeply as pickling. Soaking is typically the most common application of this process. The material is left to soak until all the dirt or contaminates are removed from the surface. However, the work piece may also be sprayed or have solvent directly wiped on it. These two applications are typically used for spot cleaning Due to the ability of the solvent to reach in all places, virtually all parts of any shape or size can be cleaned using solvent degreasing. The only restriction lies in the size of equipment available. Solvent degreasing equipment is available in a wide variety of sizes and shapes and mainly consists of a submersion tank. However, some degreasing equipment has a circulation and filtering system or some sort of elevation mechanism.

Design considerations

Benefits

* The emissions are reduced when compared with vapor degreasing operations. * Not as much venting is required, so it is easier to quickly set up a small degreasing operation. * Liquid solvents are safer to deal with than vapor degreasing agents.

Challenges

* There is a high danger of

fire Fire is the rapid oxidation of a material (the fuel) in the exothermic chemical process of combustion, releasing heat, light, and various reaction products. At a certain point in the combustion reaction, called the ignition point, flames a ...

when using petroleum and mineral solvents. * The emissions from this type of operation, although less than those of other operations, are still considerable, and solvent degreasing has an environmental impact. * Solvents are difficult to dispose of, and there are many government regulations on them.

References

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