The next step after the selection of the filter medium and the design of the filter and housing geometries for the individual application through the use of numerical simulation, is the custom-fit production, which accurately meets all the conditions defined by the designer. This is achieved by highly qualified and motivated workers in a workshop equipped with modern processing machines. All the specialized tools and moulds for building tailor-made filters are manufactured there. Furthermore we also manufacture all the additional components belonging to a filter element, e.g. supporting tubes, filtrate collectors, housings, and connectors. The high degree of specification allows for the production of single items or small series, as well as for the production of larger quantities. All the tools and moulds produced are stored and all blueprints are archived. This rich collection and our many years of experience enable us to produce customized filter solutions within short time frames.
Pleated filter media enable the creation of large filter areas in in a small space and are consequently the means of choice for compact units like filter candles or cassettes. Our modern pleating machine enables us to pleat multi-layer media from different metal fibre fleeces and/or wire meshes, occasionally with embedded fibre fleeces from polymer or glass fibres, in a width of up to 1500 mm. The pleating results in stable elements that can withstand high mechanical stresses during continuous operation. Pleat heights are variably adjustable over a wide range.
Pleated or flat filter media are welded to the longitudinal side of cylindrical filter elements, and welding is also used to attach end caps and connectors. A variety of welding processes are available for this, which are selectedon the basis oft the materials used, the wall thicknesses of components, and the seam geometries.
Welding seams in filter elements must be not only completely impermeable, but also as fine as possible, and they must not protrude. This is because they should neither block too much filter area nor act as flow barrier. They must not attract the accumulation of debris and they must not build up dead zones. Also, the finer and smoother the welding seam is, the better is its corrosion resistance.
The most frequently applied welding processes are: plasma welding, tungsten inert gas welding, and resistance welding. In some rare cases we also apply metal inert gas welding and metal active gas welding.
For instance, tungsten inert gas welding is applied for joining high-alloy steels and all nonferrous metals. Among other things, this process is also suitable for connecting stainless steel and titanium.
Resistance welding as point or roll process allows for producing high-quality seams, which have hardly any affects on the surfaces of materials, with a good reproducibility.
Plasma welding is carried out with extremely low amperages and is thus suitable for joining very thin foils and wires. Therefore, it is the means of choice for particularly fine filter media.
As an alternative to welding, reactive adhesives or sealing compounds based on epoxy resins are available for bonding metal materials to each other or to other materials. If the appropriate adhesive and pre-treatment (cleaning, degreasing) of the surfaces are chosen, and if the adhesive is properly applied, a completely tight joints can be achieved, which exhibit high mechanical and chemical resistances and are suitable for temperatures up to 150°C. As a large number of our products are used in hygienically sensitive sectors, like the pharmaceutical or food industry, we use adhesives with a clearance certificate for product contact. The adhesives are certified according to EU 1935/2004 for food contact and according to FDA (US Food & Drug Administration) regulations.
In the manufacture and assembly of highly sensitive filter elements and systems, super clean components, which are enclosed in vacuum packs filled with inert gas, are brought into our cleanroom where they are glued and assembled into high-end modules under cleanroom conditions.