![]() ![]() This arguably reflects the fact that the labor cost to maintain or replace the coolant, as well as to clean the coolant tank, is not marginal at all. The cost reduction by changing wet machining to MQL machining is much larger than expected from the discussion as to power reduction above, despite biodegradable cutting oils for MQL machining are expensive. Machining costs for wet and MQL machining were estimated by HORKOS Corporation, a leading Japanese machine tool builder, in Figure 5 ( 8). Some forecasts suggest that the electric power used in machining lines could be cut down roughly by half if cleaning of machined parts also becomes unnecessary by adopting MQL machining. This also means that the reduction in electric power by eliminating coolant pumps is substantial, and hence it is indicated that CO 2 inevitably emitted during generating electricity will also be considerably reduced by replacing the flood coolant method with the MQL machining system. These data lucidly illustrate that coolant pumps consume the largest portion of power in the machining lines. Before Toyota Motor Corporation and Mazda Motor Corporation implemented the MQL machining system in their machining lines, the extra power used for coolant-related equipment against the total electric power reached as high as 42% in Toyota, Figure 3 ( 7), and 34% in Mazda, Figure 4 ( 6), but the power actually used for driving spindles was only 16% of the total power, Figure 3, though cleaners of machined parts spent as much as 18%, Figure 4. This salient feature further leads to the reduction in electric power necessary for pumps or other coolant-related equipment, which are indispensable in wet machining. The author thus believes that the expense for installing the mist collector is not peculiar to MQL machining alone.Īs long as chips can be disposed without flood coolant, MQL machining does not require any coolant pump. Especially in machining with high pressure coolant, a myriad of fine particles of mineral oil-based coolant will be generated when the coolant impinge upon the cutting tool, work, spindle, table, and so on, likely resulting in serious health hazards. Some readers may be concerned about the extra cost incurred by installing mist collectors, but those readers are encouraged to be reminded that the mist collector is also highly recommended to introduce in machining with high pressure coolant or flood coolant all the same. Hence, the mist collector is always indispensable in MQL machining. Note that as much oil mist sprayed to the cutting region as possible must later be recovered with a mist collector, because fine oil droplets can go deep inside human lungs to cause serious health problems. It thus becomes economically possible to replace mineral oil with expensive biodegradable oils such as vegetable oils and synthetic esters, which are preferable not only for preserving the global environment but also for eliminating health hazards in humans as well as improving the work environment. Oil consumption in MQL machining operations can hugely be cut down and waste of coolant produced in machining lines can be reduced as well ( 1). Obikawa, in Comprehensive Materials Processing, 2014 11.11.1.2 Environmental and Cost Adaptabilities of MQL Machining ![]()
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