It depends....Most important thing is that, I work the machine in an office where it hasn't installed compressor,also, my spindle is too noisy when it is at high revolution. This method works for me under these parameters and, frankly , i know many people adopt other methods.....During the learning period of my cutting work, i did mostly on aluminium, many milling cutters were broken because of lack of proper coolant. Today, i can use one piece for a longer period of time. This is a tutorial fee i paid for...
White color milky type coolant works well in carrying chips and heat away the cutter especially in doing micro type millings.
Right, much installation is needed at the early stage, building srroundings to collect coolant, filtering, re-circulation for re-using the collected coolant. In long terms, it is cheaper....