Liquid coating for industrial products

For high-quality surfaces with an excellent gloss level, liquid coating is the first choice for almost all substrates. Thanks to the large selection of suitable materials and a wide range of colors, including metallic, high-gloss and effect paints, there are virtually no limits to the customization of surfaces. By using functional coatings, for example, the corrosion or fire resistance of a surface can be optimized or the electrical conductivity can be specifically adjusted.

WAGNER offers components and solutions for the automatic and manual application of liquid paints using various atomization technologies (airless, AirCoat, airspray, high rotation). These include mechanical and electronic mixing and dosing systems for 2K to 4K materials, high-performance feeding pumps, modular booth systems and easy-to-operate control units. Reliability, durability and process-reliable surface quality are at the heart of all solutions.

Liquid coating

We supply you with the right solution - whether manual or automatic, low or high pressure, individual components or coordinated systems.

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Product categories in liquid coating

liquid coating of bicycle frame with wagner equipment

Applying

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control unit liquid coating by wagner

Controlling

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Project Manager at KMF Kemptener Maschinenfabrik

 

We used to paint around 1,500 cylinders a day in 3-shift operation, including Saturday work. Today, we can cover the same volume from Monday to Friday in 2-shift operation.

Bernhard Wirnharter

Project Manager at KMF Kemptener Maschinenfabrik

Process in industrial liquid coating

A system consisting of application and feeding technology specially tailored to the area of application is more cost-efficient than all-round systems that are not configured to customer specifications. The choice of the right solution depends on various factors, including the requirements of the paint material, viscosity, number of workpieces, variety of colors or production speed. Manual systems (such as the TOPFINISH GM 1030G manual gun) are suitable for applying smaller quantities of material. Automated systems (e.g. with the TOPFINISH GA 1020/1030 automatic gun) increase productivity and are used for medium to large batch sizes.

    Surface coating step by step

    1. Pre-treatment: In order to achieve optimum, long-lasting protection and a perfect appearance of the coating, good preparation of the substrate is crucial. The aim is to remove dust, oil, grease and moisture from the substrate. Depending on the material, physical pre-treatment (e.g. sanding, sandblasting) or chemical pre-treatment (wet chemical treatment) may be necessary.
       
    2. Liquid coating: There are three sub-processes in industrial liquid coating: Material feeding, including material routing and automated color change processes, the mixing process for 2K, 3K or 4K materials where applicable, and the application of the paint by atomizing the material into microscopically small droplets that hit the substrate. The precise selection of components and the setting of operating parameters for all three sub-processes are crucial for optimum surface quality. More information on sub-processes can be found under point 3.
       
    3. Drying: One-component paints are liquid during processing and cure in the air after application. Two-component lacquers are also liquid, but unlike conventional lacquers, they cure through a chemical reaction with the hardener. UV lacquers dry and cross-link under the influence of UV radiation. A coating contains several substances in an organic or water-based solvent. After drying, during which the solvent evaporates, the previously solid substances regain their consistency.

    Sub-processes of liquid coating

    The right pump system depends on parameters such as paint viscosity, flow behavior, number of color changes, the combination of primer, paint and top coat (2K) and the number of applicators to be supplied.

    Piston pumps
    Thanks to their high durability and reliability, piston pumps are the ideal choice for applications with low, medium and high pressure, even at high application rates, as well as for the application of water-based and solvent-based paints. Highly efficient air motors ensure smooth operation.

    Diaphragm pumps
    The diaphragm pump technology combines a small internal volume with high stroke frequency for high delivery rates and very low flushing agent consumption when changing colors or cleaning. In addition, the material is conveyed very gently, as no packing or friction interferes with the material flow. The hermetically sealed design makes these pumps suitable for moisture-sensitive materials such as isocyanates. With the Cobra pump family, WAGNER offers a unique technology that makes the advantages of diaphragm pumps available for high-pressure applications up to 250 bar. 

    Pressure tanks
    Pressure tanks fulfill several tasks at the same time: storage, pressurization & material transport. The contents of the pressure tanks are pressurized with compressed air. The material supply from pressure tanks is absolutely pulsation-free and continuous. It is suitable for a working pressure of up to 8 bar.

    With multi-component materials, the exact adjustment of the mixing ratio of the individual components and an extremely good homogenization of the mixed material are crucial for an optimum surface. Electronic mixing systems ensure that a preset mixing ratio is precisely maintained. They work as an inline system so that only as much material is mixed as is conveyed to the gun and no mixed material has to be provided in advance. WAGNER mixing systems use the innovative AIS process, which enables a very even distribution of the individual components during the mixing process. The additional downstream static mixer ensures homogeneous mixing of the hardener with the base coat. The mixed material is fed to the gun via the hose and atomized at the nozzle. WAGNER's electronic mixing and dosing systems offer a choice of different measuring methods depending on the application: Feed stroke meters (magnetic stroke meters), gear measuring cells and Coriolis measuring cells.

    The choice of the right atomization method depends on several factors: desired surface quality, function of the coating, application efficiency, working speed and coating thickness.

    Airspray (air atomizing)
    The classic form of paint atomization. The paint is atomized at a low material pressure (usually between 1-3 bar) by the atomizing air supplied (also at 1-3 bar). This produces very fine and small droplets, which leads to high-quality results.

    Airless (pressure atomizing)
    Airless atomization process in which the material is conveyed through a nozzle opening under very high pressure (up to 530 bar). This technology enables fast application speed, low overspray and high application efficiency.

    AirCoat (air and material atomizing)
    The AirCoat process combines the advantages of airspray and airless atomization. The AirCoat process is characterized by the higher material pressure of up to 250 bar, with which the material is conveyed through a nozzle and thus atomized. Additional atomizing air is added to the spray jet, which enables finer atomization and makes the spray jet particularly soft and homogeneous. This achieves a high coating speed and low paint mist formation with a very good coating quality at the same time.

    High-speed rotation atomizing
    The material is atomized by centrifugal forces on a bell-shaped plate running at a very high speed (approx. 20,000 - 80,000 rpm). The shaped vents of an air deflection ring guide the material in the desired direction and adjust the size of the spray cloud as required (200 - 700 mm). Very fine atomization is achieved with comparatively large material application rates. The additional use of electrostatic charging reduces overspray and thus optimizes the application efficiency.

    Electrostatic liquid coating

    In electrostatic coating processes, the paint particles are negatively charged electrically while the workpiece is placed at earth potential. The charged paint particles follow the electric field lines and are thus actively directed onto the workpiece. This process is so efficient that both the front and back of the workpiece are coated at the same time thanks to the wrap-around effect, which massively increases the application efficiency. This makes electrostatic application a very economical process with minimal overspray and excellent surface properties. It is used for airspray and AirCoat applications, as well as for high-speed rotation atomization.

    Free whitepaper

    Find out more about the basics of electrostatics, the limits and opportunities of this technology and why it is worth investing in this economical and environmentally friendly process.

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    Application examples for liquid coating

    WAGNER offers solutions for various industries and requirements.

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    Application areas of industrial liquid coating

    Liquid coating is suitable for almost all substrates, including wood, metal and plastic. The wide range of colors and effects of the coating materials allows a high degree of customization. The selection of the appropriate application method depends on the material to be processed, the required surface quality and layer thickness and, last but not least, the required surface performance. For example, the airless process is often used for corrosion protection, while airspray coating is used for high-quality furniture surfaces, for example.  

    Typical applications:

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    Advantages of industrial liquid coating

    • Suitable for almost all substrates
    • Wide variety of colors, effects, surface textures, gloss levels and functions
    • Surfaces with high chemical resistance and mechanical strength
    • Suitable for heavy-duty corrosion protection
    • Very thin layer thicknesses possible
    • Electrostatic process enables high application efficiency
    • Uncomplicated drying sections possible
    • Multi-component systems for optimized process times and increased productivity
    • From manual coating up to automatic and robot systems

    Product recommendations for industrial liquid coating

    high-pressure double diaphragm pump cobra by wagner

    Cobra

    The unique Cobra high-pressure double diaphragm pump is ideal for airless and AirCoat applications up to 250 bar and can be used for a wide range of materials.

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    2k smart c by wagner

    2K Smart C

    Ready for immediate use: The 2K Smart C is a complete, individually configurable solution for the ready-to-spray preparation of multi-component coatings.

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    twincontrol mixing unit by wagner

    TwinControl

    The TwinControl mixing system is ideal for processing 2K material when only a few color changes are required and offers great savings potential.

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    high-speed rotation atomizer by wagner

    TOPFINISH RobotBell 1 / Bell 1S

    WAGNER high-speed rotation atomizers are ideal for electrostatic application with water-based and solvent-based paints.

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    topfinish gm 1030p by wagner

    TOPFINISH GM 1030P

    The TOPFINISH GM 1030P manual airspray gun ensures a precise spray pattern and is also extremely versatile.

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    topfinish ga 1020/1030 by wagner

    TOPFINISH GA 1020/1030

    Universal airspray gun for automatic liquid applications - for reliable coating in continuous operation.

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    Frequently asked questions about liquid coating

    Liquid coating is a process in which paint dissolved in organic or aqueous solvents is applied to the workpiece using various atomization technologies.

    Depending on the requirements (coating quality, durability, surface structure, layer thickness, etc.), the appropriate surface technology must be selected. In general, most materials can be powder and liquid coated.

    The selected coating process and its settings are decisive. The lower the material and air pressure set on the applicator, the better the electrostatic effect. The reason is simple: the kinetic energy of the paint droplets is superimposed on the force of attraction in the electric field. The smaller the droplet size and the kinetic energy introduced, the more coverage and less overspray is generated.

    Depending on the application, water-based or solvent-based paints are suitable. For environmental reasons, the use of water-based paints is playing an increasingly important role. However, increased energy costs for drying must also be taken into account.

    Electrostatic coating with water-based paints is more complex due to the electrical conductivity of the material and can be carried out using two different types of charging: With internal charging, the water-based paint is charged either in the applicator or in the paint container - the entire system is under high voltage and must be insulated against earth potential and - for safety reasons - against contact. With external charging, the water-based paint is charged with electrodes positioned outside the spray jet due to its high conductivity. The high voltage emitted via the electrode ring ionizes the ambient air so that the sprayed material is charged. This process is used in particular for high-speed rotation atomizers and is frequently used in the automotive industry.