The overall mechanism of an air compressor is a piston or rotary component (e.g. rotary screw or vane) that draws in surroundings, which is compressed into a storage tank. Naturally, since the piston or rotary component needs 
to move consistently and smoothly for this to function, it generally needs to be lubricated.
In a lubricated air compressor, there is lubricating oil which keeps the piston or rotary element running smoothly without damaging the system. The lubricant also helps to dissipate heat and maintain air compression efficiency.
Oil-free of charge air compressors also use a piston or rotary element, however they bypass the lubrication Water Lubricated Air Compressor problem by coating the compression component with a pre-lubricating materials like Teflon. Some oil-free compressors could also use water in place of oil for the lubricating and cooling procedure. These alternate materials defend the pump and allow the mechanism to move smoothly with no need for any oil-based or synthetic lubrication.