There's no question; people who want to create perfect surfaces in metal processing need clean cooling lubricant. Yet in order to be able to act successfully on the market, the economic side of cooling lubricant cleaning must also be considered. The MicroPur® superfine filter from KNOLL Maschinenbau scores many plus points for cleaning grinding oils. It achieves filter fineness of less than 3 µm and works without filter consumables, which makes it especially economical and environmentally friendly.
For a long time, precoat filters were second to none for grinding oil cleaning in hard metal, HSS and cast material processing. But the expensive filter systems that rely on auxiliary filter materials such as diatomite and cellulose have a serious disadvantage: the large quantities of consumables, disposal of these consumables, and the transport of oil result in high costs.
An alternative that can score points with regard to economy and environmental friendliness are superfine filter systems that work without filter aids and consume significantly less energy thanks to soft filtration. The best example is the MicroPur® filter from KNOLL Maschinenbau, Bad Saulgau. It contains backflushable filter cartridges like the ones used in other areas of oil filtration. This allows it to reach a nominal filter fineness of 1 to 3 µm, which fulfills the strictest requirements. In combination with an integrated sludge concentrator, for carbide metal, the MicroPur® can reduce residual moisture to four percent in the sludge. These types of dry chips can generally be sold as recyclables. At least there are no disposal costs.
"Purely for economic reasons, backflushable superfine systems like the MicroPur® will be our future," ensures Karl-Rudolf Vogel, Team Manager Product Development at KNOLL. "Because they also provide process-technical strengths, backflushable superfine filters have already overtaken and largely replaced precoat filters for grinding carbide metal. For HSS grinding and various steel types, many customers are already using the MicroPur® with two-stage filtration. For cast materials, it is even used with pre-separation and spares us expensive magnetic technology." Layer filters for grinding solutions have been replaced with MicroPur® technology for three years already; they omit the time-consuming preparation and disposal of quartz sand, which is tainted with environmentally harmful heavy metals.
Time for a system change
This is due essentially to these filters' economic efficiency. Even acquiring a filter system that operates based on the precoat principle is more expensive than acquiring one with backflushable filter cartridges. For the handling of diatomite and cellulose requires additional peripheral equipment. But the incidental costs are what truly make a precoat filter expensive. This is because the auxiliary medium has to be changed up to several times each day. The procurement and disposal costs add up; and in addition, the oil transported has to be replaced.
By contrast, MicroPur® scores points with its filter cartridges. Due to their star-shaped folding, these special elements have an especially large filter area with a cleaning output of approximately 60 l/min per cartridge. Generally, the cartridges are installed in a housing in pairs. Therefore, in the MicroPur® 480 standard filter, there are four housings, which are double-fitted. The filter cartridges can be flushed individually with cleaning oil without interrupting the filter process – a central feature of this filter. In order to achieve as effective a backflushing as possible, KNOLL uses a special flushing pump.
Filter systems in all sizes
KNOLL offers the MicroPur® superfine filter in different performance classes and as central systems in freely-scalable sizes. The smallest model is the MicroPur® Mini. It is a mobile filter column, which can be moved from machine to machine for mobile cleaning in order to satisfy cleaning requirements. The current standard models of the MicroPur® begin with the MicroPur® 60, which has a backflushable filter cartridge. Accordingly, sizes 120, 240, 480 contain additional filter cartridges. The numbers correspond to the cleaning output in liters per minute. Starting at 480 l/min and above, a clever modular system is used. Frequently, the KNOLL MicroPur® filter is used in individually-configured, central filter systems for entire production areas. The largest current system is designed for a cleaning output of nearly 26,000 liters per minute.
KNOLL's MicroPur® sets standards:
Precisely for grinding processing, where very precise contours and high surface qualifies are created, well cared-for, clean cooling lubricant is especially important. Even the least contamination can have a negative impact on the work results. Thus, high-quality filtration of the cooling lubricant is a "must." Given the cost pressure to which chipping processors are subjected, the filtration used should also be assessed with regard to its economic efficiency. Here, precoat filters with consumables such as diatomite and cellulose have clear disadvantages as compared to backflushable superfine filter systems such as the KNOLL MicroPur® systems, which function without filter aids. In many application cases, these can win people over with filter fineness in the low µm range and low operating costs. In addition, there are significant advantages with respect to environmental friendliness since with these systems, there is almost no special waste that has to be disposed of.
STATEMENT from Karl-Rudolf Vogel, Team Manager Product Development at KNOLL