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| There are four categories of cutting fluids according to chemical formulation: | (1) cutting oils, (2) emulsified oils, (3) semichemical fluids, and (4) chemical fluids. |
| cutting oils | are based on oil derived from petrolcum, animal, marine, or vegetable origin. Mineral oils (petroleum based) are the principal type because of their abundance and generally desirable lubricating characteristics |
| emulsified oils | consist of oil droplets suspended in water. The fluid is made by blending oil (usually mineral oil) in water using a~ emulsifying agent to promote blending and stability of the emulsion |
| chemical fluids | are chemicals in a water solution rather than oils in emulsion. The dissolved chemicals include compounds of sulfur, chlorine, and phosphorous, plus wetting agents. The chemicals are intended to provide some degree oflubrication to the solution |
| semichemical fluids | have small amounts of emulsified oil added to increase the lubricating characteristics of the cutting fluid. In effect, they are a hybrid class between chemical fluids and emulsified oils. |
| The most common application method of cutting fluids is | flooding |
| flooding | sometimes called floodcooling because it is generally used with coolant-type cutting fluids. In flooding, a steady stream of fluid is directed at the tool-work or tool-chip interface of the machining operation. |
| mist application | primarily used for water-based cutting fluids. In this method the fluid is directed at the operation in the form of a highspeed mist carried by a pressurized air stream. |
| manual application | by means of a squirt can or paint brush is sometimes used for applying lubricants in tapping and other operations where cutting speeds are low and friction is a problem |
| Preferred properties of tool materials | Toughness, Hot Hardness, Wear Resistant |
| Multiple-Cutting-Edge Tools | Drilling, milling, broaches, saw blades |
| Filtration systems are being installed in numerous machine shops today to solve the contamination problem. Advantages of these systems include | (1) prolonged cutting fluid life between changes-instead of replacing the fluid once or twice per month, coolant lives of 1 year have been reported; (2) reduced fluid disposal cost, since disposal is much less frequent when a filter is used; (3) cleaner cutting fluid for better working environment and reduced health hazards; (4) lower machine tool maintenance; and (5) longer tool life |
| dry machining | meaning that no cutting fluid is used |
| Dry machining avoids the problems of cutting fluid contamination, disposal, and filtration, but can lead to problems of its own | (1) overheating the tool, (2) operating at lower cutting speeds and production rates to prolong tool life, and (3) absence of chip removal benefits in grinding and milling. Cutting-tool producers have developed certain grades of carbides and coated carbides for use in dry machining. |
| Alternative ways of dealing with the problem of contaminated cutting fluids are to | (1) replace the cutting fluid at regular and frequent intervals (perhaps twice per month); (2) use a filtration system to continuously or periodically clean the fluid; or (3) dry machining, that is, machine without cutting fluids |
