Die-cutting is an essential process in pressure-sensitive label production, yet it is often overlooked by the technical departments of label printing companies. The quality of die-cutting directly affects the end-user experience. Among common issues, "label flying" or "label lifting" (where labels are pulled away with the waste matrix during stripping) is a persistent and troublesome problem. So, what specifically causes this issue?
01. Insufficient Die-Cutting Depth
If the die-cutting blade fails to completely cut through the face material, the waste matrix can easily pull the labels away, causing "flying labels." Additionally, if the adhesive layer is not fully severed, it can also lead to labels being carried off with the waste. This happens because the adhesive under the waste matrix bonds with the adhesive under the labels, causing labels to be intermittently lifted, often with a "stringing" effect.
02. Adhesive Reflow After Die-Cutting
In high-temperature environments, adhesive fluidity increases. If there is a significant distance between the die-cutting station and the waste stripping station, the previously cut adhesive layer can reflow and re-bond. In this case, the location and number of labels lifted by the waste matrix are irregular. When separating the label from the waste, obvious stringing can be observed. This phenomenon is similar to stringing caused by an incompletely cut adhesive layer but can be distinguished by a staining method: for adhesive reflow, the die-cut depth is relatively deep, and blade marks are visible on the silicone layer of the release liner. If the adhesive layer is not fully cut, the die-cut depth is shallow, with faint or no blade marks on the silicone layer.
To reduce the probability of adhesive reflow, shorten the distance between the die-cutting and waste stripping stations. Increasing the waste stripping angle can help minimize stringing. Smaller-diameter waste stripping rollers and larger stripping angles can help quickly peel the waste matrix, reducing its adhesion to the label adhesive and facilitating separation.
03. Defects in the Die-Cutting Blade
If labels are consistently lifted from the same position on the waste matrix, carefully peel the label off and examine the point under magnification. If torn paper fibers are found, it usually indicates a (nick) in the blade, a dull blade, or a depression in the corresponding anvil position. This results from the face material not being fully cut due to blade issues, similar to problems caused by gaps at the blade ends.
04. Excessive Waste Matrix Area
For circular, drum-shaped, or specially shaped labels, a larger ratio of waste matrix area to label area increases the pulling force during waste stripping, making it easier to lift labels. Adding extra blades within the waste matrix area on the die plate can the force during stripping, reducing label lifting.
05. Low Adhesive Peel Force
Low peel force of the pressure-sensitive adhesive can cause "flying labels" during die-cutting and rewinding. Two main reasons:
(1) The adhesive's peel force is inherently set too low, or the material has been stored too long, causing changes in the adhesive and silicone.
(2) Storage or processing temperatures are too low. Frozen adhesive that hasn't thawed, or a hardened adhesive layer in a cold environment, reduces adhesion to the release liner.
06. Excessive Thickness and Stiffness of Label Face Material
Thicker or denser face materials generally have higher stiffness. After die-cutting, stiff labels passing over relatively small-diameter guide rollers can easily separate from the liner ("fly off"). They are also prone to dropping or flying during automatic label dispensing. Therefore, thick (e.g., laminated labels), stiff, and high-density materials are unsuitable for small labels.
07. Adhesive Buildup on Die Blade Causing Peripheral Pre-Lifting
If adhesive sticks to the die blade when it cuts through the adhesive layer, lifting the blade can partially peel the label's edges from the liner, creating a pre-lifted state. Smaller labels are more susceptible to flying during waste stripping and rewinding.
08. Incorrect Use of Stripping (Ejection) Sponge
Installing stripping/ejection sponge behind the label areas on the die plate helps hold labels down when the blade retracts, preventing pre-lifting. No sponge should be installed behind the waste matrix areas, allowing them to pre-lift and separate more easily from the liner. Correct sponge use ensures smoother waste stripping and significantly reduces flying for small labels. Medium-density ejection sponge is recommended for flatbed dies.
09. Low Ambient Temperature
Low temperatures can also cause flying labels. Cold hardens the adhesive and makes film materials stiff and less flexible. Hardened adhesive has poorer bonding to the liner and lower peel force. This type of flying often occurs during rewinding after die-cutting, slitting into small rolls, or automatic label application.
10. Excessive Tension in Label Lamination
For laminated labels, excessive lamination tension stretches the film, causing it to curl toward the face material after lamination. After die-cutting and waste stripping, individual labels, the constraint of surrounding material, may curl up, leading to flying during rewinding or automatic dispensing. To check lamination tension, do not peel the die-cut laminated label directly from the liner. Instead, simulate automatic dispensing by curling the liner to push the label off, letting it fall naturally adhesive-side down onto a flat silicone-coated surface. A properly tensioned label will lie flat; one with excessive tension will curl up at the ends toward the face material.
Post time: May-09-2026