Mill coolant system design
Insoluble Contaminants. Insoluble contaminants are dispersed in solution and usually can be removed easily by mechanical means. These contaminants typically are generated as a part of the process. Common examples include metal oxides, machine grease, machine oils, metal fines, and metal slivers. The solids are removed with screens and filters, and the liquids typically float on the coolant and can be skimmed or vacuumed.
Baffles, perforated steel, wire mesh, roll media, and submersed conveyors are used individually or together to remove large impurities from the coolant before it is sent from the mill (preferably by gravity) back to the reservoir. Particle size can be measured using a variety of methods so that removal of the contaminant can be cross-referenced to a specific mesh size.
Keep in mind that this type of straining usually is used to catch solids larger than 10 microns that are easily visible. The ideal strainer first collects larger particles that then build up to a point that they become filters themselves, creating a molecular sieve.
Bag or cartridge-style filters are used to remove the smaller solid particles that are suspended in the coolant and that often are not seen easily. These types of filters can be used to remove particles as small as 1 micron under the pressure of a pump; however, bear in mind that there will be a significant loss of pressure going through an inline filter as the solids build in the filter media. Five to10-micron filtration is recommended, and using two filters in series (a primary and backup) allows you to change filter media without affecting production.
