Unloading Systems

(Courtesy Nordson Corp.)

No matter how much material your process requires, a dependable, cost-efficient unloading system must be devised to transport the necessary quantity to the point of application. From minute amounts of cyanoacrylates required for electronics applications to large adhesive and sealant quantities necessary in transportation or aerospace, many options are available.

For smaller material amounts, there are suppliers who offer single and two-part adhesive packaging and dispensing solutions employing convenient, disposable 30 to 400 cc cartridges and syringes. In powder or pellet form, many systems can accommodate material amounts from 20 kilograms to supersacks. When handling hot melt or liquid adhesives, unloaders are available to carry materials in 5-, 55- and 300-gallon containers directly from a truck or rail car. If necessary, automatic refilling can be considered to help streamline plant operations by alleviating manual material handling

When considering your options, it is important to calculate how much adhesive will be used per assembly and how many assemblies will be produced per day. This will help you select the right package size, based on a reasonable number of changeovers per day and adhesive shelf life. In addition, if frequent changeovers are required, an automatic unloading system can be considered to reduce labor costs.

Regardless, the unloading system must match the adhesive form.


Drums, pails and totes are often used to package larger amounts of adhesives and sealants. To unload material from these containers, three options are typically available depending on material temperature, viscosity and pressure requirements – pressure pots, suction pumps and follower-plate pumps.

  1. Manual Pouring into Pressure Pot or Tank

    Pressurized containers meet various cold adhesive delivery requirements with a range of filling capacities, typically from .26 gallons to 7.9 gallons. These containers 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. Manual filling works best for materials less than 1,000 cps.

  2. Suction Pump

    Piston and diaphragm suction pumps maximize the delivery of easily flowable cold adhesives, including PVA, solvent-based, starch and dextrin adhesives for packaging, converting and product assembly applications.

    Piston pumps can accommodate 5-gallon to 55-gallon containers for precise adhesive application at higher pressures. They maintain consistent adhesive output, typically offering balanced air motor up to 120 liters per hour (31.7 gal/hour). Most piston pumps can be designed to meet specific installation requirements, offering wall-mount, lid-mount and system-trolley configurations and independent orientation of filter and motor sections. Suction fed piston pumps work best for materials less than 10,000 cps.

    Diaphragm pumps are used for low-pressure, constant adhesive delivery up to 50 liters per minute (13.3 gal/min) or 100 liters per minute (26.6 gal/min). They typically produce reliable output at low pressures with 1:1 air-to-fluid pressure ratio. Like piston pumps, diaphragm pumps can meet most application requirements with stand-alone or lid-mount design. Diaphragm pumps work best for materials under 7,500 cps.

  3. Follower Plate Pump

    Follower plate pumps can be used to unload ambient and heated materials. Two types of follower plate pumps are available – bulk melters for precise application of heated materials and bulk unloaders for ambient pastes and mastics.

    Bulk melters deliver simple, low-maintenance application of hot melt adhesives, sealants and butyls. Modular, non-stick platens, available for 200-liter (55-gal) drums, melt adhesive on only the top surface of the drum, reducing thermal stress and protecting bonding characteristics. Various platen designs are usually available – from smooth platens for moisture-cure, reactive hot melt adhesives; axial platens for high melt rates; or finned platens for highest melt rates. Many offer added flexibility with gear pumps that offer preset pump speeds, graphic user-interfaces and manual pressure control.

    Bulk unloaders dispense high-viscosity, ambient-temperature adhesives and sealants for a variety of manufacturing applications. Available in 20- and 200-liter (5- and 55-gal) capacities, their durable design provides superior flow properties and maximum operating time. Most bulk unloaders are designed with large internal passages that minimize flow resistance and material shearing to maintain consistent material viscosity with less degradation. Typically, bulk unloaders can accommodate changing application requirements with interchangeable air motors, pumps and follower plates. Many also offer a wide range of options to customize


Typically, manufacturers will receive adhesives and/or sealants in pellets, slats or bricks for applications that require heated delivery. In this form, material is often unloaded in one of two ways – through manually scooping them into the hot melt tank or by using an automatic pneumatic filling system.

  1. Manual Scooping into Tank

    Pellets, slats or pastilles of adhesive material can be manually scooped into hot melt dispensing tanks, providing relatively easy operation at high performance levels. Tanks are available in a wide range of capacities, including 4, 7, 10, 12, 15, 25, 30, 50, 100 and 200 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 selectable 2-, 4-, 6- or more applicator 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.

  2. Automatic Pneumatic Filling

    When using pellets in small form, an integrated automatic adhesive melter and pneumatic fill system is ideal for meeting some production needs. Using a level sensor, the system detects low adhesive levels in the melter tank and automatically conveys fresh adhesive in the form of pellets, pastilles or mini-slats to the adhesive tank. Automation relieves operators from frequent refilling of melter tanks and prevents tanks from running dry.

    The automatic adhesive replenishment saves the operator time, helps prevent thermal shock and adhesive degradation. What’s more, the uninterrupted operation eliminates missed beads, poor bonding and downtime due to empty adhesive melter tank.

    Automatic pneumatic filling systems can be used with a variety of shipping containers, including sacks, supersacks and totes.


Courtesy NordsonTubes 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 yo 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. Manual Application

    Material can be unloaded from the cartridge or tube and manually applied with a squeeze bottle or hand syringe. However, this method can result in variable product quality, higher labor costs and the risk of chemical exposure.

  2. Manually Driven Cartridge Guns

    Versatile, inexpensive manual dispensers are ideal for touchups, low-volume assembly and field work. Although they still produce variable product quality, manually driven cartridge guns reduce the risk of chemical exposure. They can be used with a wide variety of syringe barrels, pistons and tips.

  3. Air-Powered Cartridge Unloading

    For operator-controlled dispensing applications that do not require a timed shot, air-powered cartridges provide accurate timing and reasonably reproducible quality if the material viscosity is controlled. Cartridge dispensers offer fast, controlled application of dots, beads and fills with less operator fatigue than manual methods. Typically, cartridge dispensers can handle all fluid types, with vacuum control to prevent dripping and ensure clean cut-off. They are operated with an electric foot pedal.

  4. Metered Cartridge Unloading

    Providing the highest product quality regardless of material viscosity, these linear pumps are typically servo-controlled, volume displacement pumps. This method -- when combined with the appropriate software – allows for a wide range of patterns, dots, lines and spiral fills with multiple shot sizes in the same program. Metered, positive-displacement pumps also provide high flow rates for higher throughputs, speeding productivity.