Aplicación: Spray adhesives evenly and economically
Why adhesives are sprayed
Adhesives are sprayed when large surfaces need to be wetted quickly, complex contours reached or thin, uniform adhesive films produced. Spray application suits many pumpable and atomisable adhesive systems, provided that the material manufacturer approves the process. These may include water- or solvent-based dispersion, contact, pressure-sensitive and specialist adhesives.
The advantage lies in the flexible distribution of the material. Depending on the nozzle and motion sequence, the adhesive can be applied to a full surface, stripe-shaped, punctual or only on selected areas. At the same time, adhesives must be prevented from landing outside the intended zone or from drying in the nozzle.
Typical materials, components and industries
The adhesive application via spray gun or automatic spray gun is used in very different production environments. Typical examples are:
- Paper, paperboard and packaging bonding
- Foam, upholstery and insulation bonding
- Wood, furniture and interior fittings
- Automotive interior, cladding and acoustic components
- Leather, textiles, foils and flexible materials
- Lamination and production of composite components
- Plastic, metal and rubber-metal components
- technical bonding processes with defined sections
Decisive are adhesive film, wetting and open time
A bonding process only works if adhesive, substrate and joining process fit together. The applied quantity must be sufficient for safe wetting, but the drying and joining time must not be unnecessarily extended. In the case of contact adhesives, a two-sided application may be required. For other systems, one-sided wetting is sufficient. Open time, flash-off time and pressing pressure are specified by the adhesive manufacturer and must be taken into account in plant planning.
In the case of absorbent substrates, part of the adhesive can penetrate into the material. Smooth or low-energy surfaces, on the other hand, place higher demands on wetting and pretreatment. The spray technique cannot replace these material properties, but must produce the intended adhesive film reproducibly.
Spraying Typical Challenges in Glue
Adhesives can have very different flow properties depending on their formulation. Stringing, pulsating material flow, clogged nozzles or an excessively broad spray mist directly affect quality and consumption.
- constant application quantity despite fluctuating viscosity
- sharp limitation of the adhesive surface and low overspray
- even wetting without defects or material nests
- Avoiding stringing and after-dripping
- suitable material handling for solvent-containing or reactive media
- Short rinsing and cleaning times
- Consideration of pot life, flash-off time and production speed
Limits and selection of suitable adhesive system
Not every adhesive can be processed with a classic air atomisation. Very highly viscous, strongly filled or extremely fast reacting systems may require larger cross-sections, other application processes or special tempering. Melting adhesives and sealant or structural adhesives to be applied in a rape form are therefore not automatically processed using the same technology as thin-liquid spray adhesives.
Before design, it is clarified whether the adhesive may be atomized, which layer shape is required and which safety and exhaust air conditions apply. This avoids the use of a supposedly universal spray system, although the adhesive process requires another dosing or application technique.
- Release of the adhesive for spray application
- Viscosity and permissible dilution
- single or double-sided application
- Surface film, strip or dot pattern
- Reactivity, pot life and cleaning
Krautzberger solutions for spray application and material supply
Krautzberger regards adhesive application and material supply as a complete system. Manual spray guns with adapted nozzle design can be used for manual workstations. In automated lines, automatic spray guns take over short, reproducible spray pulses or continuous spray paths. The choice of flat or round beam depends on component width, contour and desired adhesive surface.
Material pressure vessels are suitable for small to medium quantities and pressure that can be adjusted reliably. Diaphragm pumps, pump lifting stations and material pressure regulators can be used for continuous supply from containers. Agitators help with media that separate or settle. Material changeover valves and flushing systems support frequent product changes and reduce downtime.
Automation and integration in adhesive systems
In series processes, the spray guns can be integrated on axes, lifting devices or robots. Spray start and spray end are synchronized with component position, cycle time and web speed. This means that the adhesive can only be applied where it is needed for the joining process.
The planning must also take into account extraction, explosion protection in solvent-containing media, accessibility for maintenance as well as the cleaning of pipes and nozzles. In the case of multi-component adhesives, mixing ratio, pot life and dead volume shall be assessed separately; an appropriateness of the components must be tested according to the application.
Advantages of a coordinated adhesive application
- even adhesive films and reproducible wetting
- Reduced adhesive consumption
- fast coating of large or complex surfaces
- flexible full and partial surface bonding
- reduced rework through clean limitation
- manual and automated solutions with coordinated material supply
Tests with original glue in the Krautzberger technical test center
Adhesives with similar names can differ considerably in viscosity, solids content, solvent base, wetting, stringing and drying. The technical test centre therefore uses the original adhesive and representative sample components. The tests assess pumpability, spray pattern, application quantity, wetting, open time and cleaning behaviour.
On this basis, spray gun, nozzle, material pressure, distance, motion sequence and material supply are defined. The final adhesive strength and process release are carried out together with the operator and the adhesive manufacturer.
Related products
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Contact for your adhesive process
Are you looking for a glue gun, a paint gun for adhesives, an automatic sprayer or a complete material supply? Krautzberger supports you with the technical design from the material container to the automated coating and adhesive system.
Get in touch with us and talk to us about adhesive, substrate, application quantity, cycle time and desired joining result.
Industries for this application
Adhesive can be sprayed over full surfaces, in strips or onto selected areas. Whether packaging, leather, furniture parts or vehicle components are involved, the material, component geometry and required adhesive film determine how application must be guided and confined.
