Pre-Treatments: Effective cleaning and preparation of components
Pre-treatment is a chemical process in which the surface of the component to be coated is cleaned and prepared for the coating operation. Our team selects the appropriate chemical for the metal substrate. This can be dependent on size, customer specification, and additional process requirements.
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Our Range of Pre-Treatments include:
A type of conversion coating that forms a complete film on the part surface. This changes the chemical and physical nature of the metal surface. As a result, an iron oxide base is developed, followed by a metal phosphate topcoat. The treated metal surface will typically have a grey to blue iridescent finish. This will depend on the coating weight and the base metal.
In our iron phosphate process, the cleaning and coating are combined by the incorporation of a detergent surfactant into the iron phosphate solution. Parts treated with our Iron phosphate pre-treatment will typically achieve 300-400 hours of salt spray resistance. This is dependent on the subsequent coating system.
Our Toran3 polymer system is supplied by Envirometal Technologies and works using Plaforization. *Plaforization is a unique and patented treatment. It’s used for multi-metal products which, when dipped or sprayed with fluids at ambient temperature, are degreased, phosphate/polymerised, protected and prepared, in one, single operation. This can be for the immediate or future application of either powder or liquid paint.
Toran 3 does not contain phosphoric acid but works in a double-cure system with powder coating systems. Greases and oils on the metal are dissolved and chemically transformed, forming part of the clear protective layer laid down on the product. This layer is impervious to water and gives high adhesion for paint. Any dirt, dust or metal particles are washed from the product and then filtered out. Plaforization™ does not generate any waste for notifiable disposal. No sludge, no waste water, no VOC. It is, therefore, one of our most environmentally friendly pre-treatment processes.*
Parts treated with our Toran3 pre-treatment will typically achieve 600-700 hours of salt spray resistance (dependent on subsequent coating system). Some tests will achieve in excess of 1000 hours. *Source – www. envirometaltech.co.uk.
Our Oxsilan chemical is manufactured by Chemetall and is an eco-friendly and multi-metal pre-treatment process. **The Oxsilan® process is based on silanes that form aqueous solutions, through hydrolysis and condensation, polysiloxanes. During the coating process, the reactive silanol groups can be chemically bonded to the metal as well as to the paint coating.
Heat treatment, e.g. following cathodic electropainting (CEP), further cross-links the polysiloxanes. This creates layers in the range of 100 nm. In combination with many paint systems, this is already sufficient to achieve the same degree of corrosion protection as with the ten times thicker zinc-phosphating layers,. This thereby reduces materials consumption and pre-treatment times, as well as increasing productivity.**
Parts treated with our Oxsilan chemical will typically achieve a minimum of 1000 hours of salt spray resistance (dependent on subsequent coating system). **Source – www.chemetall.com
Another type of conversion coating is Zinc phosphate. It is a non-metallic, crystalline coating that chemically adheres to the substrate. Zinc phosphate coatings are extremely adherent. They provide a uniform coating with improved coating adhesion properties, better coating in recessed areas and better corrosion resistance. They have also been widely used in the automotive sector for many years. Unlike Iron Phosphate treatments, zinc phosphate is unable to clean and coat simultaneously. Therefore our 8-stage zinc phosphate line includes cleaning, rinsing, and conditioning stages.
We believe that correct chemical selection is an essential part of the coating process. Our team will assess the most effective method to achieve our customer’s end result. If you’re not sure which one is best for you, please contact us for advice.
The performance of any coating is significantly influenced by its ability to adhere properly to the substrate material. As the first stage of the metal finishing process, surface preparation is an essential element to ensure subsequent coating success. Surface preparation methods are used to remove surface contaminants such as scale, rust, oxide edges caused by the manufacturing process together with existing coatings. We are able to offer a variety of both mechanical and chemical preparation methods that include those mentioned on the right.
Pickling is a chemical surface preparation treatment used to remove contaminants such as scale or oxide from steel to obtain a clean surface. Parts to be treated are immersed in a bath, called pickle liquor, made up of a suitable mixture of acids. An inhibitor is added to this tank to prevent further attack and pitting of the cleaned metal. Steel components processed by acid-pickling will oxidise (rust) rapidly when exposed to moist atmospheric conditions. To prevent this, a thin film of oil or similar waterproof coating is applied to avoid contact of pickled steel with moisture in the air. Our pickling process is particularly suited for thin gauge materials that are unsuitable for shot blasting as they may become distorted.
Our pyrolysis furnace provides an economical existing coating removal process by the sensitive control of heat and oxygen during the furnace cycle. This entire process takes place in an environment with a very low oxygen concentration, thus there is no aggressive burning, which damages the objects from which the paint is being removed. All the substances and gases released are heated to 850 °C – 1100 °C at which any harmful substances are burnt. This is why this type of paint removal is very environmentally friendly. Parts would then typically move on to the shot blast process to remove any residues of the existing coating, however, the time taken to shot blast items once they have passed through our pyrolysis furnace is vastly reduced, providing a more economical solution for our customers.
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