Filter technology for grinding

As many components are expected to offer ever better surfaces, the finest grinding and polishing work is increasing. This produces an increased number of tiny particles that contaminate cooling lubricants and grinding oils. At its GrindingHub exhibition stand 7D40 in Hall 7 KNOLL Maschinenbau will show how filter solutions can be customised for a wide variety of grinding applications – with the universal HydroPur hydrostatic filter, the two-stage MicroPur® superfine filter with KF-E compact filter and UniPur canister filter as a bypass system.

Filter technology for grinding

The KNOLL exhibition stand (Hall 7, Stand 7D40) showcases the HydroPur hydrostatic filtration unit, which can be configured as needed by the customer thanks to the modular design.

The KNOLL superfine filter MicroPur® is perfect for the tool grinding of carbide metal and HSS. It achieves a filter fineness of less than 3 µm.

The KNOLL UniPur canister filter is a cost-effective, manual alternative to self-cleaning filters. It is very versatile. For example, it is ideal in combination with a HydroPur filter to separate even the finest particles in the bypass.

High-quality grinding results always require optimum cleaning of the grinding oils or other cooling lubricants. However, as the chip load varies in terms of size and shape depending on the material being processed and the respective abrasive, the user should also configure their filter technology accordingly.

KNOLL offers the HydroPur hydrostatic filter as an all-round filter solution. This modular universal filter comprises a tank and filter upper part with a fine filter fleece, which when combined with the hydrostatic principle separates fluid and chips. It is suitable for a wide range of applications, but is particularly suitable for grinding due to the flat discharge angle. The basic tank and filter components can be supplemented with pumps, coolers, etc. as required - from the simplest equipment to the full version, which then fulfils even the most demanding requirements.

An innovation: While the HydroPur hydrostatic filter previously offered was limited to a size with a flow rate of 400 l/min, in future there will be other models covering the performance range from 200 to 1000 l/min.

The non-plus-ultra solution: the superfine filter MicroPur®

The KNOLL superfine filter MicroPur® is designed from the outset for ultra-fine filtration. It is perfect for the tool grinding of carbide metal and HSS. But it also delivers optimal 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 and sustainability.

At GrindingHub 2024, KNOLL will be showcasing the standard MicroPur® 240 model including an integrated desludge concentrator in a two-stage filter system. This means that the ultra-fine filter is supported by a KF-E compact filter, which removes coarser contaminants from the coolant and thus relieves the MicroPur®.

Such a solution is ideal for grinding and polishing HSS tools or other steel components. This is because these materials produce not only ultra-fine particles but also longer, fibrous chips, which must be separated in advance to ensure a long service life of the MicroPur®. One growing area of application for such two-stage filter solutions is gear wheels for electric mobility, for example. In order to minimise running noise, these are polished after grinding, creating the aforementioned ultra-fine particles. Another application example is the grinding of hard-coated brake discs, a trend topic at GrindingHub. The hard material layer consists of stainless steel with embedded carbides. Grinding produces both larger grinding chips and very fine particles, which are reliably separated from the cooling lubricant by a two-stage MicroPur ® superfine filter.

Bypass filtration for better cooling lubricant quality

KNOLL's third exhibit is the UniPur canister filter, a cost-effective, manual alternative to self-cleaning filters. The UniPur is versatile: in the main or secondary flow, as an additional filter (additional filter stage, bath treatment, police filter) or as a standalone filter for small volume flows. KNOLL offers various filter cartridges and bags for different applications, which guarantee a filter fineness range of 1 μm to 100 μm. The maximum volume flow per housing is 500 l/min.

The UniPur is ideal for use as a bypass filter for grinding applications that do not require full-flow filtration of the finest chips. Equipped with a MicroPur® filter cartridge, it is able to remove even the finest particles from the cooling lubricant in standalone operation, for example downstream of the HydroPur hydrostatic filter. This means that bath treatment is also possible at times when there is little staff, for example at weekends.


You will find KNOLL Maschinenbau at Stand 7D40 in Hall 7 at GrindingHub 2024.