Industry sector: Surface treatment – surface coating
Company activity: Chemical treatment and painting of metal surfaces
Company type: SME
Company founded: 1970s
Contacts: President – Maintenance and servicing manager
Company context
The company develops surface-treatment solutions (phosphating degreasers, passivation, anti-corrosion treatments, etc.) and paint coatings on all types of metal substrates (steel, aluminium, galvanised steel, zinc, etc.). These surface coatings are used, for example, on guardrails, gates, public lighting, civil engineering structures, and more. The company uses filters in particular on its powder-coating extraction systems.
Filtration challenge
The client was looking for a new supplier of pleated conical filter cartridges (over 150 cartridges to replace) installed on its equipment. This supplier change provided an opportunity to reconsider the manufacturing technology of the paint-powder filters used, in order to move towards more robust filtration media.
Pemflow filtration solution
We recommended that the company opt for paint-booth filters using filter cartridges in which the joints between the filter media are made using ultrasonic heat-sealing, whereas most manufacturers offer filter cartridges where the pleat bonding is done with adhesive.
1 – Pleated conical filter – powder-coating filter
2 – Technical section of a filter cartridge optimised for the filtration equipment required in surface-treatment applications
For over 4 years, and thanks in particular to development work carried out with the Navier Laboratory at Université Paris-Est, we have been able to weld together pieces of plastic filter media by locally melting the synthetic material from which they are made.
High-frequency ultrasonic vibrations are transmitted to the interface of the two parts to be welded via a welding head called a sonotrode. The energy released creates a local melt of the material, thereby welding the parts together.
This thermomechanical coupling can be applied to filters with complex geometric shapes and guarantees unmatched strength. The mechanical resistance at the weld joint is at least 70% higher than that of the filter media itself. Ultrasonic welding creates a homogeneous, dense layer of plastic material at the junction — the polymer density is twice that of the filter media.
In contrast, with simple adhesive bonding, two interfaces remain: one between the adhesive and each surface. In this configuration, the strength is not consistent along the entire bond line, as the amount of adhesive is never exactly the same at every point of the glued area.
Our filter cartridges with thermally welded media can therefore withstand compressed-air pressures up to 15 bar, whereas typical usage conditions usually guarantee between 5 and 7 bar.
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