Delivery Systems

(Courtesy Nordson Corp.)

A large range of product technologies is available for the delivery of adhesive and sealant material in assembly operations. When considering your options, it is important to consider the requirements of your specific application. These include adhesive type, pressure, viscosity, required accuracy and/or the need for purging during dispense cycles.

Pressure-Based

Pressure-based systems are often used in higher-output manufacturing operations where accuracy and repeatability are not critical to product quality. Two options are typically available for pressure-based material delivery – pressure pots or air-driven pumps.






  1. Pressure Pot

    Pressure pots are suitable for waterborne and solventborne adhesives with low pressure and controlled viscosity. These containers meet various cold adhesive delivery requirements with a range of filling capacities, typically from 1 liter (0.26 gallons) to 30 liters (7.9 gallons). Pressure pots provide protection against corrosion with wetted fittings and tank casings made of stainless steel. They can also improve bonding performance by incorporating adhesive filters that remove contaminants. Many pressurized containers also offer wide openings and straight-wall designs that speed manual filling and cleaning. Manually filling pressurized containers can be labor intensive, and manufacturers must consider the costs associated with such labor as well as spillage.

  2. Air-Driven Pump

    Air-driven pumps are designed to deliver material at higher pressures, with repeatability dependent on viscosity control. A wide range of adhesive melters are available with air-driven technology, offering capacities to meet most any application need. Based on specific requirements, melters with air-driven pumps are available with capacities of 4, 7, 10, 12, 15, 25, 30, 50 and 100 liters.

    Many also offer select 2-, 4- or 6-gun operation to expand as your production needs change. Melter options vary from the most basic to highly sophisticated, with some providing graphic operator interfaces, touch-screens, quick disconnects, select control features and high-end diagnostic capabilities.

    Regardless of the option you choose, most melters are designed to enhance the performance of hot melt adhesives by preventing any control zone temperature from exceeding the leading zone temperature, causing all to reach setpoint temperature simultaneously.



Metered

Metered material delivery is typically used in applications that require levels of high accuracy. These delivery methods include variable speed gear pumps, shot pumps or positive displacement applicators to achieve desired results.

  1. Variable Speed Gear Pumps

    Many adhesive melters incorporate variable speed gear pumps designed for precise, demanding hot melt adhesive applications. These pumps assure excellent accuracy and continuous availability. The variable-speed AC motors and key-to-line functionality satisfies a wide range of industries and manufacturing requirements, although they are not appropriate for shear-sensitive or highly filled adhesives . In addition, these melters are typically easy to install, operate and maintain, maximizing productivity. Many also offer versatile control panels with a choice of programming methods using either a keypad or arrow keys.

  2. Shot Pump

    Servo-driven shot meters provide excellent dispensing accuracy, but also requires refill time in cycle. Shot pumps combine shot meter technology with proportional control to provide precise, repeatable deposition and efficient material usage. They can provide multiple shot sizes and are not affected by material viscosity changes. Shot pumps are typically designed for the robotic application of automotive adhesives and sealant materials. When "bead on the part" appearance and consistent command of bead profiles are crucial to product quality and function, the shot pump provides an excellent solution.







  3. Positive Displacement Applicator

    Ideal for specialized applications, like those in the electronics industry, positivedisplacement applicators are not affected by fluid viscosity, supply pressure, needle size or fluid/pump temperature. As a result, they can be used for dispensing a wide range of patterns, dots, lines and spiral fills for filled and unfilled fluids. Most can achieve extremely high accuracy levels for consistent dispensing with multiple programmable shot sizes. In addition, many positive displacement applicators offer benefits that include rapid refill speeds, fast priming, minimal material waste, and high flow rates for faster throughput. A quick-release mechanism and few wetted parts provide tool-free disassembly and assembly for easy cleaning.

Hot Melt Tanks

Courtesy NordsonHot melt tanks can be used with either pressure-based or metered delivery options to provide system temperature control. A wide variety of adhesive melters are available, based on application specifics.

Tanks are available in a wide range of capacities, including 4, 7, 10, 12, 15, 25, 30, 50 and 100 liters to meet most any application need. Based on specific requirements – including speed, method of delivery and application,

Today’s most reliable melters use either piston-pump or all electric technology, with many offering select 2-, 4- or 6-gun operation to expand as your production needs change. Melter options vary from the most basic to highly sophisticated, with some offering graphic operator interfaces, touch-screens, quick disconnects, select control features and high-end diagnostic capabilities.

Regardless of the melter you choose, most are designed to enhance the performance of hot melt adhesives by preventing any control zone temperature from exceeding the leading zone temperature, causing all to reach setpoint temperature simultaneously.

Meter/Mix

Metered material delivery is typically used in applications that require levels of high accuracy. These delivery methods include variable speed gear pumps, shot pumps or positive displacement applicators to achieve desired results. Any of these metered options can be combined with static or dynamic mixing heads to enhance material delivery.

  1. Static Mixer

    With all-plastic assemblies, static mixers are ideal for messy or short pot-life adhesives. Their low cost allows for disposal of the mixer instead of solvent purging or furnace cleaning. The housing is transparent, allowing for operator inspection of the mixer. They offer the toughness and chemical-resistance to be completely inert to all common solvents. For adhesive and sealant mixing applications, optional polypropylene mixing elements are typically available.












  2. Dynamic Mixer

    Dynamic mixers are ideal for difficult-to-mix urethanes and epoxies and typically require purging. Their unique design combines dynamic mixing with low-cost, disposable mixing chambers. Dynamic mixers are an excellent choice for casting and molding applications such as RTM, potting and encapsulation.

    Ideal for use with new meter-mix systems or retrofitted to improve mixing in an existing system, dynamic mixers have A and B components that are separately ported through the gun body and manifold and do not combine until they meet inside the disposable mixing chamber. Other design features include helical impeller elements, adjustable rotation speeds for high shear and complete mixing.