Auxiliary Equipment

(Courtesy Nordson Corp.)

In addition to unloading, delivery and application equipment, many auxiliaries are available to help develop a complete integrated dispensing solution for your adhesives and sealants.

Robotics

Robots are a cost-effective way to increase throughput and quality and reduce production costs by automating repetitive fluid dispensing tasks. Many robots feature integrated time and pressure controls that regulate the operation of the valve or syringe barrel without the need for an external controller. They are available with 325mm x 325mm or 525mm x 525mm work envelopes, and are easy to program with a handheld PDA and user-friendly software.

For processes where product changeovers are frequent, 4-axis robots are available that permit CAD drawings to be downloaded and used to simplify setup.

SCARA robots can also be used with conveyors and products with high profiles.

Robots are typically compatible with readily available syringe barrels and dispense valves.

Web Handling

Web coaters produce quality products with separately driven laminating station, retractable coating applicator and web edge guide. They are available to apply coating widths up to 380 mm (15 in.). Today’s leading designs feature a cantilevered design for easy operation, with view and control system operation from a functional operator panel.







Controls

Tubes and cartridges are often used to package small amounts of adhesives and sealants, often used in applications where precision dispensing systems is required for applying controlled amounts to deliver material supplied in these smaller packages to the point of application, four options are typically available. The method of unloading is typically based upon the amount of precision dispensing required. They include manual application, manually driven cartridge guns, air-powered cartridge unloading and meter cartridge unloading.

  1. Timers

    Flexible pattern controls deliver precise adhesive placement for constant- or variable-speed packaging lines. Easy to install and operate, many such timers can accommodate random-size cases and provide real-time pattern adjustment capability. Most timers can store up to four consecutive trigger events, providing flexible trigger location and closer product spacing to maximize operational efficiencies and productivity.

  2. Verification

    Modular pattern control and verification systems provide a building-block approach to integrating control and verification capabilities as needed. Verification systems protect product integrity by inspecting adhesive volume and position, bar codes, overlapped or skewed substrates, cellophane windows, security tags and flap faults. The system controls and verifies hot melt and cold adhesive placement and volume even for short runs and even complex patterns. Verification systems can typically be used in applications up to 1200 meters per minute (3937 fpm) with pattern accuracy of ±0.25 mm (0.01 in.).

  3. Closed-Loop Controllers

    Closed-loop controllers are computer-based management systems to monitor and control the major variables of a material dispensing operation for maximum accuracy. System diagnostics quickly identify faults in the dispensing process such as the dispensed volumes, material supply pressure, temperature conditioning and auxiliary equipment. This immediate fault recognition reduces part rejects and downtime.

    Interfacing with a personal computer, the controller provides Internet access capability, color touch screen display, online manuals, help screens and data logging.

  4. SPC

    Statistical process controllers provide a simple, accurate system for monitoring a wide range of functions during the material dispensing process. These versatile controllers allow supervision of material pressure and dispense volumes and can be used in two modes, accommodating systems that use either on/off dispensing modules or other guns. SPCcontrollers typically have a 32-part ID capacity, and memory chips can also be added for optional data logging. An RTD input is provided to monitor material temperature for SPC data, if desired.

Surface Preparation

One of the most prevalent concerns when bonding materials is how to get a strong bond between mismatched substrate surfaces. Generally, when bonding like materials, there are adhesives available that will strongly bond the two surfaces at the interface of the substrates. However, in many manufacturing scenarios the need to bond different materials with very dissimilar physical and chemical properties frequently arises. For example, a reasonably rigid material such as polycarbonate (PC) may need to be bonded to a more elastic polyethylene (PE) material. Since the chemical makeup of these materials is quite different, they will tend to bond differently to various adhesives. A certain adhesive may bond well to the PC, but not well – if at all – to the PE, and vice versa.

There are methods to chemically treat the surface of one or both of the materials using primers, solvent cleaners or degreasers. While many of these chemical methods work quite well, they require the use of materials that may expose the manufacturer to dangerous or toxic matter. Such materials may also require expensive or time-consuming disposal methods. Most importantly, many toxic or dangerous materials cannot be used in the manufacture of medical devices that are implanted in the human body.

Other mechanical means, such as sanding or corona/flame treating, are also used to get a strong adhesive bond. However, of all the surface treatment methods, plasma has a proven application and manufacturing history helping bond dissimilar materials including metals and various plastics. It can reduce manufacturing time and costs by potentially eliminating the need for primers. Stronger bonds from plasma can be a combination of several plasma processes. Depending on the process gas selected, plasma can clean, activate and roughen the surface to optimize the strength and quality of the bond by enhancing the physical and chemical aspects of the bond.




Curing

Adhesives and sealants all require curing after application. As production requirements for faster turnaround, increased line speeds, greater productivity and improved efficiency have become more demanding, manufacturers are increasingly looking for the best curing solution.

Ovens and EB/IR methods can be employed to provide adequate curing of a substrate. However, ultraviolet (UV) curing systems are emerging as the most reliable, durable and cost-effective for a wide range of products. Whether the product is wood, plastic, glass or other heat-sensitive substrate, UV curing systems deliver greater application flexibility with a range of precisely focused and flood reflector geometries. They emit no ozone. Dichroic-coated temperature stable glass reflectors provide cooler operation, and no internal gasketing virtually eliminates the possibility of arcing.

Foaming

Foaming systems produce homogenous foam material by mixing inert gas with typical flowable sealants. The gas expands to create a closed-cell foam as the material is manually or robotically applied to components. As a result, foaming systems typically deliver 40-50 percent gas content of mixture, providing economical material usage, faster cure time of materials and reduced gasket weight.

The system processes and dispenses a variety of high-performance materials, including silicones, urethanes and plastisols at elevated or ambient temperatures. No chemicals are used in the foaming process so foamed sealants retain their basic physical properties, such as temperature and chemical resistance. The gas content of the foamed material can be adjusted to control material durometer, compression set resistance and flexibility.