6 Reasons Why Your Hot Melt Adhesive Isn’t Working

In a recent blog, we shared the most common misconceptions when it comes to boxes popping open, what causes them, and how you can fix them.

Today, we are going to share varying reasons why your hot melt adhesive isn’t working and what you can do to fix it.

If you’re like many manufacturers, you may experience a problem with adhesives, leading to faulty packaging, waste and potential claims.

Here’s a closer look at 6 of the most common adhesive problems manufacturers face today, and possible adhesive solutions for those problems.

Poor adhesion

One of the top adhesive problems is plain poor adhesion.

Sometimes, adhesives just fail and it’s frustrating to try and decipher what the root cause may be.

Whether your adhesives fail due to an insufficient amount of adhesive or a poor contact between the surfaces being adhered, here are some solutions for when your adhesion is downright poor.

  • Is your adhesive only on one surface?
    • Try applying heavier glue film thickness or raise the temperature
  • Is your adhesive on both surfaces, but showing “legs”?
    • This is commonly caused by disturbing the bond while still in a semi-molten state. Try checking the compression or using a faster setting adhesive.
  • Is your hot melt glossy?
    • This is commonly caused by poor or non-contact of surfaces being adhered. Try adjusting the pressure to keep glued surfaces together while hot melt cools.
  • Does your bond separate easily?
    • Try using a more suitable product. Our Bond Tech experts can help you find the right adhesive for your needs.

Charring of adhesive

Adhesive charring occurs when the properties of the adhesive are altered through thermal and oxidative degradation.

When adhesive charring happens, all you’re left with is hard clumps that have lost their thermoplastic nature and will not flow, therefore stripping the product of virtually all adhesive properties.

  • Is the temperature too high in the tank?
    • Try lowering the temperature.
  • Is the hot melt charring on the side walls of the tank?
    • Try keeping the tank filled.
  • Is air oxidizing the hot melt?
    • Try keeping the tank covered.
  • Bond Tech has many non-charring formulations! Ask us about these.

Gelling of adhesive

Adhesive gelling is another issue that results in wasted product, increased down time, and higher expenses, but it is easily avoidable.

  • Is your adhesive overheating?
    • Try a lower temperature or ask us about our low-temp hot melts
  • Is your adhesive mixed with incompatible adhesives?
    • Check with your Bond Tech representative
  • Is your hot melt adhesive unstable?
    • Check with your Bond Tech representative

Schedule an adhesive audit

Stringing

Another common hot melt adhesive problem that can occur during the manufacturing process is stringing.

This happens when some of the adhesive material is left behind on the nozzle and gets pulled down the line, which is especially common in packaging applications.

To reduce stringing, Bond Tech recommends the following:

  • Is your running temperature too low?
    • Try raising the temperature, but be cautious as too high of a temperature can cause heat instability.
  • Is your stock temperature too low?
    • Try pre-warming the stock.
  • Is the timing or alignment of your carton flap to the applicator roll poor?
    • Try adjusting the machine.
  • Is the nozzle shutoff poor?
    • Try cleaning and repairing nozzle shutoff.
  • Are you using the right adhesive for the application? Ask us.

Adhesive not flowing evenly from all nozzles

 

An important element of a successful adhesive is the adhesive properly flowing from the nozzle to the application.

However, this is not always the case.

  • Is your nozzle clogged?
    • Try cleaning or repairing the nozzle and or the filters.
  • Is your remote nozzle in multitude nozzle set-up affected by a pressure drop?
    • Try increasing the temperature or pressure slightly and put larger orifice openings on remote nozzles.

Fuming or smoking

The last issue is adhesive fuming or smoking, which can be easily avoided with these tips:

  • Does your adhesive equipment have poor heat control?
    • Try using a calibrated thermometer or reset the thermostat.
    • Are you running too hot? Check adhesive specs for recommended running temperature.
  • Does your hot melt adhesive have poor heat stability?
    • Try reducing the temperature to the minimum needed for a good bond.
  • Contact us to learn about other hot melt formulations that can prevent many of the aforementioned issues!

It’s important to keep in mind that open pots are more often than not the culprit for smoke, so be sure to cover reservoirs or premelters whenever possible to avoid smoking or fuming.

Want to learn more?

There is no shortage of potential problems that adhesives may present in your packaging process. However, there are plenty of solutions, too.

If you still have questions or concerns regarding your adhesives, contact us to speak with an expert and we’ll be happy to help!

Contact us today to discuss how our product selection can meet your needs.
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