Extraction for
aluminium 

A well-known manufacturer of extruded profiles, surface treatments and precision sawing work with 300 employees asked SPÄNEX, within the framework of a larger investment project, to remove the chips produced on 4 aluminium processing machines, which are equipped with sawing, drilling and milling units.

The specific system design and planning had to be preceded by a test in order to be able to determine the design and placement of the collection units and, derived from this, the collection air quantities. It is generally known that the capture air volume and the degree of capture in particular determine the effectiveness of the extraction and the energy requirement. In general, the extraction bonnets should be designed in such a way that the chips are completely collected with the minimum possible extraction air volume. It should not be overlooked that the degree of extraction has a decisive influence on the cleaning effort and thus the availability of the processing machine..

In the on-site test, the geometries of the hoods, the arrangement and the assigned air volumes were determined under practical conditions in an iterative process and thus the basic data for the development of the offer were determined.

The tests showed that the targeted collection of the chips drastically reduced the amount of cooling lubricants used, as the rinsing out of the chips produced, which is typical for wet machining, was not necessary. It was immediately recognised by those responsible that the significantly lower use of cooling lubricants would not only bring considerable cost advantages, but at the same time create much better working and environmental conditions for the operating personnel.

Based on the data and findings obtained during the tests and the spatial conditions, the following solution was proposed:

1.  3 individual dust extractors of the serial SMU are used for the extraction of the 4 processing machines.

2.  To keep the extraction rate constant, the extraction fans are speed-controlled via frequency converters.

3. The aluminium chips are disposed of by means of slide gates with feeding onto a conveyor belt for further transport into a container.

to 1.:

The dust extractors used represent complete extraction stations which are characterised by the following features:

• compact design,

• pressure shock resistant housing,

• filter chamber with integrated pre-separator,

• filter elements - oil and water repellent,

• effective cleaning system,

• high-performance fan on the clean-air side,

• container with discharging system and slide gate,

• powder extinguishing system with automatic triggering,

• low sound pressure level,

• electric circuit with volume flow monitoring.

The dust extractors or extraction stations, which only require a footprint of approx. 3 x 1 m, should each be arranged on a base frame and set up in the direct vicinity of the processing machines (short pipe routes - low pressure loss).

In the integrated and generously dimensioned pre-separator, most of the aluminium chips are separated from the extraction air, so that the filter elements are only loaded to a small extent with residual chips, which are removed via the effective separation. Although cooling lubricants are only used in very small quantities, the filter elements should be designed to be oil- and water-repellent.

The extraction fan on the clean-air side has a high-efficiency impeller (closed, backward curved blades - efficiency 82 %), so that energy-saving operation is already ensured in conjunction with the low internal pressure losses of the unit. The clean air chamber of the fan is lined sound-absorbing, so that an overall low sound pressure level is achieved.

The units each have a powder extinguishing device that is triggered automatically depending on the temperature or manually.