What are the hazards posed by cooling lubricant vapors?

Cooling lubricants can contain a whole range of different substances. These include, for example, biocidal substances. Employees are continuously exposed to such substances. To protect health it is therefore imperative to reduce the concentration of oil and emulsion mist in the air.

What is oil mist extraction?

The purpose of the filter system with oil mist extraction is to extracts cooling lubricant vapors from the processing areas of machine tools. Cooling lubricants (CL) usually contain oil. In this case, oil can also be the basis of the CL (non-water-soluble CL). In the majority of applications, however, it is present as a water-soluble emulsion.

What filter class does an oil mist extractor require?

The average particle size in relation to the mass is about 1.5 µm to 2.5 µm. In various grinding operations this value is even higher. With ePM1 80% filter (according to ISO 16890), aerosols of this size are filtered to the largest extent. Higher filter classes may be recommended, if critical materials shall be processed where particles need to be additionally filtered. When lubricating with minimum quantity , the particle size is somewhat smaller. Therefore, a higher filter class is sometimes used here.

How is standardization applied to the filter efficiency of oil mist separators?

Very often, the ISO 16890 is applied. The standard determines the efficiency for atmospheric aerosols with peaks of fine fractions at about 0.3 µm. This is significantly smaller than is normally the case with cooling lubricant mist. The actual ePM1 efficiency for separation of CL is therefore significantly higher than the standardized classification value. The EN779 is no longer valid for this classification. Sometimes HEPA filters standardized by EN 1822 or similar norm ISO 29463 are used. These standards determine the efficiency for the so-called "Most Penetrating Particle Size" (MPPS), i.e. the particle size that can be separated by the filter with the lowest efficiency.

Is the MultiCNC by Hengst also available with HEPA filters?

For MultiCNC by Hengst HEPA filters can be easily retrofitted. For retrofitting to achieve a longer service life for the HEPA filter, the standard Lotex 1704 pre-filter mat need to be replaced against Lotex 1805 pre-filter mat. These filter mats are already included in the HEPA filter set. Since pressure drops are higher when using this filter combination, air volume flow is reduced by approx. 100 m³/h in a newly installed condition.

Is the MultiCNC suitable for my application?

The MultiCNC is designed for a very wide range of applications. Normal concentrations and professional extraction of cooling lubricant mist (also see further information here in FAQ) makes it possible to achieve very long filter service live. The MultiCNC also operates reliably at higher concentrations. Here users need to consider that filters shall be replaced more regularly. The filter principle of the MultiCNC shows its strengths especially when emulsions are used, but advantages of light applications with oil mist are demonstrated here as well. Further information on the usually expected concentrations of CL mist are also available in DGUV Regulation 109-003 Annex 1.3.

Can an oil mist extraction system be retrofitted?

The MultiCNC by Hengst can be retrofitted very well. Many existing plants are not yet equipped with a filter unit. Since the filter unit is not included in the CE declaration of conformity of the manufacturer, it is a complete machine according to the Machinery Directive and comes with its own CE marking and a mandatory main switch with emergency stop function.

Where is the oil mist extractor mounted on a machine tool?

The MultiCNC by Hengst can often be mounted on rails and vibration dampers on the machine housing, or on a small frame next to the machine. The easiest way to connect is via a suitable flexible hose. The filter unit should ideally be arranged above the extraction point so that cooling lubricants can flow back from the extraction hose if necessary.

How should the extraction point of an oil mist extraction system be designed?

To prevent direct entry of cooling spray and chips, the extraction point should be as far away from the actual machining area as possible. On turning lathes, for example, the opposite side from the lathe chuck is often well suited. At the connection point of the extraction, a metal wire mesh is ideal for keeping coarse contaminants out. However, this must be cleaned regularly to prevent blocking. If it is expected as difficult to ensure, at least a baffle plate should be provided in front of the extraction point to capture coarse particles. If you have any further questions, please do not hesitate to contact us.

How do you monitor/check filters of an oil mist extraction system?

Many oil mist separators operate very well without instruments to monitor the filter condition. Excessive filter load or clogging of the extraction point will be noticeable through reduced air volumes. Alternatively, a pressure gauge can monitor the pressure differences of filters. A differential pressure switch can also be used to send an optional message to the machine tool. In any case, filter inspection should be included in the maintenance plan of the machine tool.

How is the electrical connection of Hengst MultiCNC made?

The connection diagram is available on the product page. Basically, the MultiCNC only requires a 230 VAC power supply with the appropriate rating (170W / 500W). In the simplest case, the unit can be activated at the beginning of the shift using the included main switch and deactivated again at the end of the shift. If required, the fan power can also be controlled with a potentiometer, a 0...10V input or a pulse width mudulation (PWM).

What controls is most reasonable for an oil mist extraction system?

If a control system for Hengst Multi CNC is required, it would be reasonable, for example, to slightly reduce the power when the door of the machine tool in the machining area is closed. If the door is opened, the power should be immediately ramped up to full capacity to maximize protection of the machine operator against escaping coolant vapors. If the door remains open, it can also be considered to regulate the MultiCNC to "0" after a preset time period expires. The follow-up time should be well considered, as the filter unit is also effective in subsequent processes, such as blowing off the workpieces with compressed air.