What should you do if the labeling strip breaks? Please check yourself for these issues.

Label breakage refers to the phenomenon where the backing paper of a label breaks during the automatic labeling process. This is one of the most common problems in automatic labeling. Once a label break occurs, the entire automatic labeling machine must stop operating until the labels are properly reloaded before work can continue. Handling a label break generally wastes 3 to 10 minutes each time. Occasional occurrences during labeling can be acceptable, but frequent occurrences will inevitably affect labeling efficiency. More seriously, many companies have their labeling production lines connected with the main production lines, so if the labeling line stops, it could also cause the production line to halt, resulting in significant economic losses for the company. So, what causes label breakage?

PART 01

Excessive die-cutting cuts the backing paper

A good way to determine the cause of automatic label breakage is to observe and analyze the broken part. If the break occurs in a very regular pattern, mostly along the die-cut lines, and the break edges are neat and without separation, this phenomenon is mostly due to excessive die-cutting that damages the backing paper.

We know that finished adhesive labels need to be die-cut into shape. In principle, during the die-cutting process, the die should only cut through the face material and the adhesive layer, and the bottom liner should not be damaged. However, in actual operation, due to equipment limitations, the liner is often cut. This is because traditional flatbed die-cutting machines usually operate in a flat-on-flat manner, where the die and the material are in surface contact. During die-cutting, the pressure may vary slightly, but it is impossible to maintain a completely consistent pressure from start to finish. Such surface-contact die-cutting machines often damage or even cut through the liner due to these minor pressure fluctuations.

Therefore, when using flat-on-flat die-cutting machines to produce self-adhesive label products, operators need to frequently check whether there is any change in die-cutting pressure. If the pressure increases and cuts the liner, it must be adjusted promptly. To check for liner damage during die-cutting, a coloring method can be used: apply a solvent-based marker to the position of the die-cutline on the liner and then wipe it off. If the color seeps into the die-cut line, this indicates that the die-cutting pressure is too high and the liner has been cut, requiring immediate adjustment of the pressure.

Of course, if you want to completely solve the problem of liner cutting, rotary die-cutting is a better solution. Rotary die-cutting equipment uses a rotary die to cut, and there is no adhesive material between the cutting roll and the counter roll. When using this equipment, the die knife makes line contact with the material, providing high cutting precision. Moreover, both the cutting roll and the counter roll undergo dynamic balance testing before leaving the factory, and in principle, the runout does not exceed 0.01 mm, which is commonly referred to as 'one silk'. This ensures minimal vibration during operation and prevents damage to the liner.

Due to the high cost of producing cutting tools for rotary die-cutting, it is more suitable for larger batch orders. For smaller orders, production costs can be quite high. However, fortunately, most automatic labeling labels are used in relatively large quantities. Some orders may not require many units of a single type, but the total quantity of multiple types is substantial, and the specifications are the same, allowing the same die to be used for cutting. Therefore, automatic labeling orders are best cut using rotary die-cutting equipment.

PART 02

Splice Quality Issues

Sometimes the labels break at very consistent points, usually starting from the splice. In such cases, we need to examine whether the splice quality is problematic. Common splice issues include:

01

Uneven Tape at Both Ends of the Splice

Currently, most label splices are joined using transparent tape or specialized industrial tape. In principle, the width of the tape at both ends of the splice should be consistent, with an error of less than 1mm. The overall tape width is 40–50mm. If the operator lacks quality awareness, significant deviations in tape width at the splice ends may cause the splice to break during automatic labeling. For example, if the total tape width is 40mm, a qualified splice requires 20mm of tape on each end. An unqualified splice might have 5mm on one side and 35mm on the other, which can easily break during high-speed operation of automatic labeling machines. During operation, the machine typically applies several to over ten kilograms of tension on the labels. Such tension, combined with high-speed movement, subjects the backing paper to substantial forces, making weak splices prone to breaking.

02

Incorrect Splice Method

In the self-adhesive industry, the splice is usually required to be a 45° angled splice, not a 90° straight splice. This is because an angled splice can distribute the force when passing through the feed rollers and label peeler of the automatic labeling machine, whereas a straight splice concentrates the stress at one point. An angled splice is more likely to ensure the label does not break under machine tension while passing the label peeler.