The cooling/lubrication situation on the cutting edge can be decided by the economy of the chipping process. Aerosol dry lubrication (ATS), which was developed by Rother and is now available from KNOLL, ensures minimal heat generation. It eliminates the need for additional cooling, it is easy to adapt, the process is reliable, and it produces high-quality processing results. In addition, ATS is significantly more cost-effective and energy-efficient than conventional cooling lubricant and MSS systems.
In order to guard against irritations: KNOLL Maschinenbau, one of the leading suppliers of systems for conveying and filtering chips and cooling lubricants in the metal machining industry, took over Rother Technology GmbH & Co. KG, Bad Urach, including all of its patents, on July 1, 2019. This means that the AerosolMaster system , which relies on the ATS (aerosol dry lubrication) technology developed by Rother, is now part of the KNOLL product line. This is true for all variants including the high-end AerosolMaster 4000 Cryolub®, which supplements ATS with cryogenic cooling technology.
For five years, KNOLL has focused intensively on alternatives to flooding cooling with cooling lubricants, which is the dominant process in the metal machining industry. For Managing Director Matthias Knoll is certain: "There are production areas where minimum quantity and dry lubrication are simply superior." With the company's own ControLube high-pressure system, in recent years KNOLL has offered a product for minimum quantity lubrication that creates a very fine aerosol and provides very good lubrication results. However, the lance through the spindle required for this proved to be a decisive disadvantage that limited the product's economic success.
The ControLube MMS system was phased out after EMO 2019. "In the future, we will use the AerosolMaster technology developed by Rother, which has replaced the ControLube system in our product line," explains Matthias Knoll. "Its core technology, aerosol dry lubrication, achieves a comparable aerosol fineness, but is much easier to adapt."
Start-up and conversion simplified
AerosolMaster has been on the market since 2009 and is reasonably widespread. Starting in the Rother era, there was intensive cooperation with leading machine tool manufacturers, who integrate the AerosolMaster into an OEM version as original equipment when customers request it. In addition, numerous chippers have retrofitted the system on their machines since this is easy to do and can be done without significantly disturbing production operation.
Conversion of conventional MMS systems and wet-cooled machines is also possible. For with ATS, the preference is to direct the aerosol through the channels of tools with internal coolant supply. If there aren't any such tools, the aerosol can also be fed through special tool attachments or external nozzles. For example, close cooperation with well-known tool chipping system manufacturers contributed to the development of special feeders for tools without internal coolant supply; these are designed so that after leaving the tool holder, the aerosol mixture is pressed directly into the tool's clamping slots. It flushes these out and, even at the highest speeds, goes directly to the cutting edge, where it can deploy its lubricating effect.
This is how aerosol dry lubrication works
Reiner Rother, former Member and Managing Director of Rother Technologie, is now responsible in his role as MMS development engineer at KNOLL for the enhancement of ATS and AerosolMaster. He explains the principle of dry lubrication: "ATS eliminates the heat that is produced by friction by directing the finest lubrication particles directly to the cutting edge and at the same time, evenly moistening the point of contact. Aside from the air stream, in most cases no additional cooling is required."
The heart of the KNOLL AerosolMaster is a pressure tank that contains the special ATS Lubricant lubricating oil, which is transformed with the carrier medium air via a special Venturi nozzle into a fine aerosol with a droplet size of 0.1 µm to 0.4 µm (average size 0.25 µm).
Furthermore, the AerosolMaster unit contains a patented control and regulation technology via which the aerosol generation and transport can be set depending on the application in question. It also ensures that the aerosol stream remains constant and that it is supplied loss-free to the cutting edge. An optimal lubrication particle application then effectively reduces the generation of friction heat.
"Even with high speeds up to 42,000 min-1 and across long distances, there is no de-mixing of the oil thanks to the extremely fine particles," emphasizes MMS specialist Rother. There is also no risk of film tear-away. In addition, the ATS medium conveys or blows the chips out of the chipping zone immediately, so that when milling deep cavities, you can be sure that the tool will not run over chips, for example.
The lubricant supply is also monitored by the controller. Depending on the system type, the refilling is either done manually or automatically via the NFA refilling unit.
Technology that increases productivity and reduces costs
The familiar restrictions of conventional MMS systems, including de-mixing, dosing, control, cable length, the use of smaller tools with a coolant channel diameter < 0.55 mm are not a problem with ATS. Instead, users report significantly better productivity and process reliability. According to Reiner Rother, due to the significantly reduced heat generation in the treatment zone, depending on the application, the service life of the milling cutter used is increased by up to 30% as compared to other MMS systems. Alternatively, with the same service life specification, the cutting data and productivity of the chipping can be increased.
And there are other cost benefits thanks to the dry chips produced (disposal) and workpieces (further processing). Give the lower lubricant consumption (approximately 3 to 25 ml/h), the high provision and disposal costs for cooling lubricants are reduced almost to zero. Furthermore machine cleaning, which must be done repeatedly with flooding cooling, is almost unnecessary with ATS. And with regard to energy efficiency, a topic on which KNOLL is focusing in many areas, the AerosolMaster systems demonstrate great potential: the energy consumption per machine is up to 60% lower as compared to central cooling lubricant systems.
The perfect ATS solution for each application
There are KNOLL AerosolMaster units for different production requirements – from the AerosolMaster 800 ATS for milling and turning machines where three different aerosol quantities are enough, to the AerosolMaster 4000 ATS, which is designed for processing processes that require many different aerosol quantities. With it, the user can select from 30 programs that are called up directly via a connection to the machine.
For heavy machining of titanium and other materials that conduct very little heat, ATS is pushed to its limits. But KNOLL also has a solution for this: the AerosolMaster 4000 Cryolub® combines ATS with cryogenic cooling technology. That is, in addition to aersol dry lubrication, liquid CO2 is fed into a separate line for the chipping contact zone; this zone can therefore be cooled to temperatures as low as -78 degrees Celsius. Like the aerosol saturation, the cooling capacity can be set as needed and thus depending on the component and material. Reiner Rother knows from experience: "While with the 'normal' AerosolMaster we achieve a productivity increase of 30 to 70%, the increase with the cryo system is between 70 and 200%. With such an effect, the machine manufacturers are even prepared to accept the additional lance through the spindle."