KOVOVÝROBA HOFFMANN, s.r.o. is one of the leading suppliers to the automotive industry. The company is based in Ostrožská Nová Ves, not far from our production facility in Boršice.

Our task was to fit an extraction system to one of the largest twin-spindle machining centres, the TRIMILL VF 11035, which produces dry, explosive dust. Our supply included a complete extraction design, including extraction fittings which were not supplied with the machine.

The worktable of the machine tool measures almost 12 m. This area is covered by a gathering curtain. Given the size of the working enclosure and the extraction method (the machine manufacturer did not offer or require extraction at the spindle), we determined the extraction capacity to be Q = ± 30,000 m³/h. We designed slotted extraction hoods for the right and left sides of the worktable. In the design, it was important to position the hoods as close as possible to the worktable, whilst ensuring there was no collision with the machine’s spindle or the workpiece being machined.

The machine’s working area can be divided into two halves by a partition, and each spindle can operate independently. We have also adapted the extraction design and control system accordingly. Both working sections of the table, and each side of them, have their own automatic flap which opens or closes the system depending on the machining method and position. The extraction capacity is controlled by a frequency converter in conjunction with a control unit that processes the relevant signals. This ensures an efficient distribution of extraction capacity and saves electricity.

The extraction units are connected by extraction pipework, which leads to our in-house CARM GH central filtration unit. The unit automatically regenerates (cleans) the filter elements using counter-flow compressed air. As with all similar applications, we guarantee a service life of at least 18,000–20,000 operating hours for the filter elements (cartridges).

The materials processed also include textite, which, when combined with air, creates an explosive atmosphere. To comply with legislation, the unit is designed in accordance with the ATEX directive – featuring pressure relief membranes, a reinforced housing, antistatic filter media, etc.

Given the nature of the dust being extracted and the potential risk of fire, the filtration system is equipped with an automatic fire-extinguishing system. Should the temperature within the filtration system rise, the system closes the inlet and outlet dampers and releases the extinguishing agent into the filtration system.

The system operates in summer and winter modes; during the summer months, the filtered air can be discharged outdoors, whilst in the winter months it is recirculated back into the hall. This system delivers significant savings in heating energy.

We consulted with TRIMILL and KOVOVÝROBA HOFFMANN on the design of the extraction fittings and the openings in the machine’s enclosure prior to the start of production. The installation of the extraction system took place alongside the installation of the machine tool. The commissioning and handover of the project also took place simultaneously.

Further details of the installed system can be seen in the attached photographs.

Ing. David Tříska