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Henkel Adhesive Technologies

Henkel Adhesive Technologies

Hot melt tank refilling

Reducing char with adhesive tank refilling best practices.
4 min.
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Attaining the perfect case and carton seal is a balance of the right hot melt packaging adhesive, the ideal operating parameters and a consistent adhesive pattern. Food and beverage manufacturers rely on hot melt packaging adhesives to assure a strong seal for their products. Unplanned downtime on a packaging line can be significantly reduced when hot melt tanks are filled consistently.

Establishing a routine for filling hot melt tanks will keep the packaging adhesive temperature consistent and prevent char formation, which can lead to plugged filters and nozzles. Issues can arise when a hot melt adhesive tank is:

  • Filled inconsistently – results in variable adhesive application temperature and pattern
  • Filled below a certain level – known as underfilling, results in overheating the adhesives and char formation
  • Filled over a certain level – known as overfilling, increases the potential for dead spots and adhesive waste

Consistent hot melt tank filling assures adhesive temperature and reduces downtime to keep production lines moving.

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Addressing hot melt adhesive issues from inconsistent filling

Understanding how to maintain operating consistency with hot melt packaging adhesive is important. Each equipment manufacturer has best practices to keep the machinery working efficiently.  Hot melt packaging adhesives, like TECHNOMELT, also have ideal operating windows. One of the keys is filling hot melt tanks correctly to achieve application consistency, maintain the equipment, and keep the production line running smoothly.

There is a science behind filling a hot melt adhesive tank. A consistent refill rate results in even temperature. This is one of the easiest ways to keep the production line moving and avoid adhesive-related downtime.  If the fill rate is inconsistent, the molten hot melt adhesive temperature can fluctuate – either too hot or too cool – causing the adhesive bead or line to vary and impacting the bond. If a tank runs lower than necessary, also known as starving the line, the result can be defects in the bond or poorly sealed packaging. Running the adhesives too low can also impact the useful life of the tank leading to increased equipment costs.  On the opposite end of the spectrum, adding too much adhesive at once will “shock” the system.  This cools the overall temperature and can stop a production line for up to 30 minutes while the hot melt adhesive reaches operating temperature. In some cases, an automatic fill system can alleviate this problem; however, monitoring is still important to assure consistency.

Two men with safety goggles discussing

Preventing hot melt adhesive issues from overfilling the tank

Operating a hot melt adhesive line for packaging has a variety of challenges.  There are several elements that impact the decision making on filling the tanks – line speed, substrate materials, and finished good demand. Well-meaning operators may fill a melter over the recommended fill line for many reasons.  In some cases, operators may overfill the tank to avoid issues that arise when hot melt adhesive reaches lower fill levels. If the hot melt tank is overfilled, the lid may be slightly ajar from too much adhesive. An open tank lid presents three problems:

  • Increased possibility of production area contaminants (dust, paper, etc.) depositing in the molten hot melt
  • Amplified risk of adhesive spills onto the shop floor
  • Added safety risk to employees from hot melt burns

Overfilling a hot melt adhesive tank can lead to adhesive contact on the lid or build up around the rim of the tank. Build up around the tank can lead to dead spots in the molten adhesive that will sit and cook over days, hours, and weeks resulting in char formation.  In some cases, an overfilled tank is mistaken for a “leaky” tank. The buildup will blacken and can be knocked into the tank and clog filters and nozzles. Most hot melt adhesive tanks have a “max” fill line. Henkel recommends adding 1 – 2 scoops of adhesive pellets at a time to maintain consistency.  This will help maintain tank temperature close to set point.  Some operators are concerned when adhesive pellets float at the top of the tank after refilling.  It is important to remember the hot melt adhesive will melt from the bottom of the tank near the heating elements. Henkel’s hot melt adhesive pellets are designed to float to avoid the cool material from sinking to the bottom and affecting overall temperature. It is recommended to “top off” a hot melt adhesive tank with a little material, frequently to avoid causing char and wasting adhesive.

Henkel employee in the factory with safety goggles handling hot melt

Troubleshooting hot melt adhesive application

Food and beverage manufacturers rely on the effectiveness of hot melt packaging adhesives to assure a strong seal or bond. Brand owners need to understand the optimum adhesive performance to produce a secure bond. To gain more insights on ways to increase efficiency of hot melt adhesive, register for Henkel’s digital training platform and learn more best practices about improving the operating life of adhesive.

hotmelt granules in melting tank


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