The right filter technology for every grinding process

Optimised cleaning of the grinding oils and other cooling lubricants is essential for high-quality grinding results. KNOLL Maschinenbau provides customised filter solutions for diverse grinding applications. Visitors to GrindingHub 2022 in Stuttgart can examine the broad selection at the KNOLL stand (Hall 7, Stand 7C20): the superfine filter MicroPur® which manages without filter consumables, the individually configurable hydrostatic filter HydroPur, the vacuum filter VLO, as well as a fluid centrifuge for bypass operation.

The right filter technology for every grinding process

The finer the machining, the higher the proportion of ultra-fine particles in the grinding oil or cooling lubricant, which in turn jeopardises the quality of the machining result. The job of the modular superfine filter MicroPur® from KNOLL Maschinenbau, Bad Saulgau, is to prevent this. It is perfect for the tool grinding of carbide metal and HSS. But it also delivers optimal filter results in the machining of castings. The MicroPur® achieves a filter fineness less than 3 µm and manages without filter consumables thanks to its special design, which makes a significant contribution to its high degree of efficiency.

At GrindingHub KNOLL showcases the standard model MicroPur® 240/900 – together with the integrated sludge concentrator AK5 matched to the capacity, which ensures automated sludge discharge. In addition to such standardised systems for individual or several machines, KNOLL also offers individual central filter systems on MicroPur® basis for entire production areas.

Anyone who needs an independent cleaning unit for grinding and would like to configure it as required is best advised with the hydrostatic filter HydroPur, which is presented for the first time at a trade fair by KNOLL. This filtration unit has a modular design. It comprises a tank and filter upper part with a fine filter fleece, which when combined with the hydrostatic principle separates fluid and chips. Pumps, coolers, etc., can be added as needed – for simple equipment through to the full version, which then meets even the most demanding requirements.

The operation of the HydroPur is also simple and very intuitive. Because KNOLL uses its new SmartConnect operating concept, with which a small industry PC is connected to the system PLC via a 7" touch display. SmartConnect also has app connectivity so that the operator can access the filtration unit on mobile end devices such as a smartphone or tablet, display statuses, as well as check and change parameters.

In addition, KNOLL presents the vacuum filter system VLO, which is ideally installed for profile grinding with machining oil. Due to simple scalability, the filtration unit can be used locally for individual machines or centrally for machine groups. Without the use of filter aids the VLO vacuum filter system achieves clean oil as well as pure, dry concentrate.

Last but not least, KNOLL presents an automatic fluid centrifuge CA 100 at GrindingHub, which is of great importance in the cleaning of grinding oil with its proven technology. It assumes the bath care in the bypass in many filter systems and prevents the accumulation of fine particles. This system technology is also popular for upgrading existing systems.

How the KNOLL HydroPur filtration unit, which is making its début at a trade fair, works:

The lifting pump of the machine tool or a lifting station conveys the contaminated cooling lubricant to the infeed box of the HydroPur and from there onto the filter fleece. The hydrostatic pressure allows the cooling lubricant to pass through the fleece, but retains chips and foreign matter. They form a filter cake, which with increasing thickness causes a decreasing flow volume through the filter surface. The level of contaminated fluid rises to a defined level, then the belt drive is switched on and conveys the filter fleece a step further. This allows clean filter fleece to reach the filter surface, the flow volume increases and the level of contaminated fluid is reduced again.

After exiting the contaminated fluid the fleece with the adhering filter cake runs across a drying section before it ends up in the collection container. KNOLL also provides an optional winding unit for the used fleece in combination with a scraper, which separates the filter cake in the container beforehand. The cleaned cooling lubricant flows into the clean tank. From there up to three pumps supply the machine tool with clean cooling lubricant as required.


The right filter technology for every grinding process