Hot Melt System Comparison

Comparing how tank-based, tankless, and Tank-Free systems work at each step of the hot melt process can help you determine which technology best suits your packaging operation.

Same Five Steps of Operation vs. Three Packaging Technologies

The operation cycle of a hot melt system consists of five crucial steps:

  1. Feeding adhesive pellets
  2. Melting the adhesive pellets
  3. Transferring the hot melt through hoses
  4. Dispensing exact amounts of adhesive onto the package
  5. Monitoring system parameters to keep production moving

While most end-of-line packaging operations have the same hot melt process, the technology used to take those steps makes the biggest difference in improving performance, safety and productivity.

Let’s compare the operation of the three main types of end-of-line packaging systems:

  • Tank-based hot melt technology relies on large tanks, where adhesive is heated and kept at a certain temperature until needed.
  • Tankless hot melt technology is the same as tank-based because it has small tank or reservoir, where adhesive is heated to and kept at temperature before it is dispensed.
  • Tank-Free™ hot melt technology does not have a tank. Instead of keeping adhesive in a reservoir until it is needed, it melts and dispenses the adhesive on-demand.

1. Feeding Adhesive Pellets




Adhesive pellets are fed manually. An operator opens the melter’s hopper and dumps in pellets.

Manual feeding exposes operators to serious safety hazards, such as exposure to heated areas, molten adhesive, and toxic fumes.

Adhesive pellets are fed automatically from the container to the machine. The hopper remains closed, keeping adhesive free of contaminants.

Automatic feeding allows operators to keep a safe distance from possible burn exposure, and eliminates the risk of inhaling toxic fumes.

How an Integrated Automatic Vacuum Feed Works

The automatic vacuum feed in an InvisiPac® Tank-Free™ melter supplies only what’s needed for application. The melt-on-demand system maintains material integrity, while reducing adhesive consumption.

2. Melting the Adhesive Pellets

Consistent melting is a critical to hot melt system operation. Unevenly heating or overheating adhesive lead to adhesive charring and thermal shocking. Both degrade the quality of the hot melt, leading to increased downtime and unplanned maintenance.

Tank-based Tankless Tank-Free

It can take more than 45 minutes for all the material in the large tank to heat to operating temperature.

Bringing a tank full of adhesive up-to-temp at once can cause overheating that easily leads to charring.

It takes up to 45 minutes for heated fins at the bottom of the small tank to melt adhesive enough to start application.

Melting from the bottom up can cause uneven heating that can lead to thermal shocking.

The absence of a tank allows for a 10-minute start-up time. The melter design has a high melting ratio.

Automatically adding adhesive into the melting chamber as needed eliminates the risk of charring and thermal shock.

Start-Up Time Comparison

See how the start-up time of a tank-based melter compares to InvisiPac Tank-Free, melt-on-demand technology.

3. Transferring the Hot Melt through Hoses

Consistent temperature remains important as adhesive moves from the melting tank or through a chamber into heated hoses to the point of dispense.

  • Uneven heating can cause hot spots, where the temperature is higher in some places than in the rest of the hose. Hot spots change the viscosity of the adhesive, resulting in inconsistent dispensing while increasing material usage.
  • Consistent temperature throughout the hose keeps adhesive viscosity constant without compromising material integrity. This ensures a constant flow of adhesive, resulting in consistent dispense.




Hot spots are common because heat is not evenly dispersed as adhesive move through hoses.

Hoses in InvisiPac Tank-Free systems have an extra silicone layer that evenly distributes the heat within the hose, eliminating the occurrence of hot spots.

4. Dispensing Exact Amounts of Adhesive onto the Package

As adhesive goes from heated hoses to hot melt applicators for dispense, it can get stuck in corners, causing dead zones. Hot melt stuck in dead zones becomes char buildup, eventually clogging the applicator or nozzle.




Most tank-based and tankless systems use applicators that, due to their design, allow adhesive to get stuck in two corners, causing dead zones.

Stuck hot melt will eventually start to burn and clog the applicator or nozzle, causing inconsistent dispense and pop-opens.

Applicators in InvisiPac Tank-Free systems have a free flow design that prevents dead zones. The adhesive is filtered as it moves through the manifold and module.

As temperature and viscosity are maintained from melter to applicator, every box gets a consistent dose of adhesive, avoiding pop-opens and reducing adhesive usage by up to 70 percent.

Applicator Plug Performance Comparison

See what happens to different hot melt applicators when they are plugged. The Graco InvisiPac Hot Melt Adhesive Applicator has a free flow design that prevents dead zones and keeps dispense consistent.

5. Monitoring System Parameters to Keep Production Moving

The ability to stay in touch with your operation by viewing the status of your hot melt system allows you to be confident in production quality, while also observing real-time performance. With the rising cost of hot melt adhesive, the ability to track adhesive usage and keep lines running is a necessity.




Solutions for monitoring critical system parameters are limited.

InvisiPac has two monitoring solutions: through an advanced display module or by adding LineSite.

Linesite™ Remote Monitoring

With the Linesite Remote Monitoring Solution for the InvisiPac Hot Melt System, you can track your plant’s hot melt operation in real-time from your smart phone, tablet or computer. End-of-line packaging information available at your fingertips includes:

  • System temperatures and critical performance metrics
  • Adhesive usage of each line
  • Machine diagnostics to help prevent common downtime causing issues
  • System operating data in an intuitive, graphical format
LineSite Monitoring and Assistance

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