Abstract:
Metal Working Fluids (MWFs) have been used over the past 200 years for different
metal cutting operations. They must provide a layer of lubricant to reduce friction, act as
a coolant to reduce heat produced and prevent metal pick-ups by flushing away the
chips. These functions will help to reduce wear on the tool, reduce energy requirement
» and to produce the desired surface quality on the work piece. MWFs can be categorized
as straight cutting oils, water-soluble fluids and gases. Out of these categories water soluble fluids are primarily used for high speed machining because they have better
cooling capabilities. Most of the cutting fluids are mineral oil-based fluidsbut they pose
significant health and environmental hazards throughout their life cycle. Therefore
alternative solutions are highly expected by the modern industrials. Research on
applicability of vegetable oil-based cutting fluids in machining metals has been
undertaken in recent years and many of them are on testing the suitability of vegetable
oils as straight cutting oils. Further water-soluble fluids were also developed using
vegetable oils such as soy bean and sunflower oils. In this research a water-soluble
MWF compose of 46.7% weight white coconut oil and a mixture of two emulsifiers was
prepared. The pH value, viscosity and biodegradability of the newly developed cutting
fluid were compared with a commercially available mineral oil-based soluble oil. It was
found, BOD5 (Biological Oxygen Demand in 5 days) of the commercial MWF is very
higher than the developed white coconut oil base MWF. End milling machining
experiments were conducted with mild steel, stainless steel and cast iron work pieces
while applying this newly developed fluid and the selected mineral oil-based soluble oil.
Surface quality and the temperature were measured and compared. The surface
temperature was lower with the new MWF compared with the commercial soluble oil
throughout the experiments during machining mild steel, stainless steel and cast iron.
Surface roughness obtained was better with the white coconut oil based new MWF
during machining mild steel and stainless steel for all selected spindle speeds. But this is
different with cast iron as cast iron is somewhat of a special case with its own built-in
lubricant.
