Pressure-sensitive labeling machines will run into faults sooner or later in use, and those faults lower the labeling pass rate. The most common are label curling, label bubbling and web breakage. Below we have put together some solutions for these three common problems for your reference.
1. Label curling
Curling happens mainly because a product is labeled before filling and is then filled and sealed: the heat of the sealing process puts a severe strain on the label, and the closer the label sits to the base, the more likely it is to curl.
Solution:
1. Increase label adhesion so that the label stays firmly in place. Control the labeling pressure and the temperature during labeling.
2. Use soft label materials wherever possible; good label flexibility greatly reduces curling.
3. Change the label shape.
Make the bottom edge of the label curved so that it stays away from the deformation zone created by sealing.
4. Eliminate the effect of static. Labeling easily generates static, which affects the result; raising the humidity in the labeling area helps to some extent, and an ionizing fan is also an effective solution.
2. Web breakage
An automatic labeling machine always applies some tension while labeling, and labels whose liner edge is nicked are easily torn under that tension, causing the web to break. Web breakage can also occur when the rollers on an automatic labeling machine are set incorrectly and crush the liner edge of the label.
Solution:
1. After pressure-sensitive labels are die-cut into finished rolls, the liner is normally left a little wider than the labels; this makes label peeling easier for the customer during labeling.
2. Prevent the finished label roll from being rewound too tightly. Over-tight rewinding squeezes adhesive out of the pressure-sensitive material, and the oozing adhesive sticks to the back of the liner so that the whole roll no longer unwinds easily.
3. Ensure clean die-cutting. Excessive die-cutting pressure cuts through the liner, lowers its tensile strength and causes web breakage. Liner breaks caused by poor die-cutting have a relatively neat fracture face, and the tear sits on the die-cut line.
4. Prevent damage to the release layer. The release layer can be damaged by coating defects during raw material production, and it can also be scratched through improper handling during inspection and label replacement at the printing plant.
3. Label bubbling
Uneven adhesive coating, poorly designed or under-pressured pressure rollers on the labeling machine, and static effects can all cause bubbles under the label.
Solution:
1. If the pressure rollers of the labeling machine are faulty in pressure setting or structural design, bubbles can also appear during pressure-sensitive label application; readjust the roller pressure, or work with the labeling machine manufacturer to resolve it.
2. Reduce static. When labeling on an automatic labeling machine, static causes bubbles and spoils the labeling result. You can lay antistatic flooring in the workshop and install ionizing fans and static grounding chains.