There was so much dust and smoke that a fine haze settled over the entire production facility. This all took place at a metalworking factory located near the southwestern German city of Heidelberg. The company concerned is a large-scale producer of steel sheets. The sheets are cut to size using a thermal process called plasma cutting. However, this largely automated process generates large amounts of dust and smoke, and so the ventilation system must be able to cope with these. It’s not an easy job, but it is essential for the health of staff and the operational safety of the machines.
In this particular case, the problem was not the size of the dust removal system, but the performance of the filter elements used. The pleats of the non-reinforced filter medium collapsed when the load was too high. This significantly reduced the effective filter area, which in turn had a considerable negative effect on filtration performance. The result was that a haze remained in the production facility.
Collapsing pleats is a common problem if they are folded tightly. There are physical reasons behind this. The greater the force the air flow applies to the medium, the more the medium bends. Eventually, it touches the nonwoven fabric of the adjacent pleats. Large loads due to high dust loading can have the same effect. It also significantly impairs cleaning performance, which is an important criterion for efficient dust removal systems.
The material must have inherent rigidity to prevent the pleats from collapsing. Flat materials do not have this.
Corrugated filter media have been proven to work.
Filter media that have such corrugation (a wave-like pattern across the pleat) retain their shape significantly longer, even at high flow velocities. This reduces the pressure drop, saves energy costs, and usually also reduces the maintenance intervals by extending the service life.
At least that’s the theory. In practice, however, not all corrugations are the same. The properties and performance data vary significantly depending on the design and filter material. It is for this reason that Freudenberg Filtration Technologies follows its very own concept and relies on deeper, wider sinusoidal grooving. The corrugation is integrated into the nonwoven at the very beginning of the nonwoven production process, as this achieves a particularly high degree of rigidity. This means that the grooves can withstand long-term stress and do not flatten during operation. This significantly reduces the risk of the pleats collapsing. Even if extreme overloading causes the pleats to collapse, the inherently rigid corrugation creates residual air channels, through which air can flow. The medium retains its original geometry while in use and returns to this geometry after loading. The installed media surface consequently remains available and effective for the filtration system. In practice, this means greater long-term efficiency and extended service life. Dimensionally stable pleating also renders filter cartridges with grooved media much easier to clean, which in turn reduces differential pressure and improves extraction performance.
Filter systems must be capable of long-term operation while requiring as little attention as possible.
This is as true of welding, cutting, polishing, and coating metallic and non-metallic materials as it is of processes in most other industries. It is also exactly what dust removal cartridges with Freudenberg’s unique corrugation achieve. They deliver full power during sustained load peaks and are easy to clean, so they remain operational for a long time. After changing filters, our customer minimized dust loading from plasma cutting, ensuring considerably safer conditions in the production facility.