Views: 0 Author: Site Editor Publish Time: 2026-09-14 Origin: Site
A hot melt labeling machine may sometimes have problems such as labels falling off, poor adhesion, glue stringing, or excess adhesive. Many people first adjust the glue temperature, but temperature is not always the main cause.
Hot melt labeling is a process involving glue application, label application, pressing, and cooling. If any part of the process is not properly controlled, labeling quality can be affected.
Here are five key areas to check.
A hot melt labeling system applies heated adhesive to the label or bottle, applies the label to the container, and then uses pressure to ensure good contact.
The adhesive must remain active long enough for the label to contact the bottle and be pressed firmly. This bonding time is often referred to as the adhesive's open time.
The amount and distribution of adhesive are important.
Too little glue can cause poor adhesion or labels falling off.
Too much glue can cause glue stringing, overflow, or contamination.
Uneven glue application can result in different bonding strength across the label.
Check the glue roller, nozzle, or other adhesive application components to make sure the hot melt is applied evenly.
After the label is applied, sufficient pressure is needed to create good contact between the label and bottle.
If the pressure is too low or uneven, you may see:
Lifted label edges
Air bubbles
Weak adhesion
Labels coming loose after application
The pressure roller should match the bottle shape and labeling speed.
Even a properly adjusted labeling machine cannot achieve stable adhesion if the bottle surface is not suitable.
Oil, dust, moisture, or condensation can reduce the bonding strength of hot melt adhesive.
For bottles stored in cold environments, condensation can be especially important. Make sure the container surface is clean and dry before labeling.
Different labels and containers may require different types of hot melt adhesive.
Consider the compatibility between:
Label material
Bottle material
Adhesive type
Production speed
Application temperature
If the adhesive is not suitable for the label or container material, increasing the temperature may not solve the problem.
Glue temperature is important, but it should not be the first and only adjustment.
If the temperature is too low, the adhesive may not melt or flow properly, resulting in weak bonding.
If the temperature is too high, the glue may become too fluid and cause stringing, excessive glue, or overflow.
Old or overheated adhesive may also become darker or degraded, which can affect application quality.
Always follow the adhesive manufacturer's recommended temperature range.
Low ambient temperatures can affect labeling performance.
When the environment is cold, the adhesive may cool faster after application. This can shorten the available bonding time before the label is pressed onto the bottle.
If this happens, check the machine insulation and working environment first. A small temperature adjustment may also help, but it should remain within the adhesive manufacturer's recommended range.
When a hot melt labeling machine has an adhesion problem, do not immediately increase the glue temperature.
A better troubleshooting sequence is:
Bottle surface → Adhesive condition → Glue application → Pressure roller → Glue temperature
This makes it easier to identify the actual cause instead of simply changing the temperature.
Stable performance from a hot melt labeling machine depends on more than adhesive temperature. Glue application, pressure, bottle surface, adhesive compatibility, and working conditions can all affect labeling quality.
If problems such as labels falling off, poor adhesion, or glue stringing continue after these checks, the machine supplier and adhesive supplier should work together to identify the cause and find the appropriate adjustment.
