The dipping of metal components into Thermoplastic powders or, Fluidised Bed dipping, as it is sometimes known, is the oldest form of plastic coating and goes back to the time when Leyfos Plastic Limited was established in 1972.
Pre-treated metal components are heated up and dipped into a fluidised bed of thermoplastic powder, the powder particles then melt onto the metalwork, forming a smooth continuous coating.
Thermoplastic coating material is ground into a fine powder and kept in a steel box (Fluid Bed) open at the top and with a fine gauze across the bottom, which allows air to be blown through the gauz and make the powder particles act as a fluid , hence fluidized bed.
Metal components are pre-treated, usually de-greased and shotblasted, heated up to between 250 and 400 degrees C depending upon the coating required, then dipped into the Fluid Bed of plastic. The Powder particles melt onto the metalwork forming a smooth continuous coating.
Coating materials used can be Low Density Polyethylene, the PPA ® range, Talisman ®, Deconyl ® Nylon 11 (Rilsan ®)
Coating materials used – Plascoat PPA Range & Rilsan , Nylon 11
Electrostatic Powder Coating consists of the spraying of highly charged fine powder particles around metal. The charged particles of powder are held onto the surface of the metal component purely by the induced (electrostatic) charge.
Both component and powder are then heated at which stage the powder melts and cures. This process provides excellent chemical resistance and electrical insulating properties
Because we apply the coating manually, we can target specific surfaces of metal products very precisely. This method lets us coat complex components such as tanks, valve casings , Structural Steel Fabrications. This technique makes it easy to switch the type of coatings and the wide range of colours available, so that the costs associated with any changeovers are limited.
Coating materials used – Polyester , PPA 571 ES , Nylon 11
High performance (PTFE) coatings
The High Performance or ‘PTFE’ Coatings section of Leyfos Plastic Ltd applies technical coatings that contain materials such as PTFE or PolyTetraFluoroEthylene, FEP or Flourinated Ethylene Propylene Copolymer, Molybdenum and Graphite. These materials are normally applied to components where a non-stick, dry lubricant, low friction or release property is required.
PTFE coatings are often known by their familiar or trade names, Teflon ®, Xylan ®, Fluoroplastic, Flouropolymer or Fluorocarbon coating and they take the form of a liquid paint which is sprayed onto a substrate (metals, rubbers, plastics etc) that needs to be enhanced.
The liquid coating contains varying proportions of the technical materials, resins and other ingredients, exactly what is contained in each of the different coatings material recipes depends upon the desired coating film performance. Often it is not just the non-stick or low friction type of performance that is required, there will be a need for corrosion resistance, chemical resistance, humidity resistance, high and low temperature resistance & even colour coding for identification.
To apply a coating, the customer’s products / components are usually prepared by degreasing and gritblasting prior to being wet sprayed with the coating material. The resulting coating is then cured to a precise schedule in a properly ventilated industrial oven. The result is a high performance dry film coating with a thickness in the region of 15 microns to 35 microns depending upon the number of coats.
Customers may specify a grade to be non-stick coatings which are used in the molding industries.