Still struggling with frayed edges when die-cutting adhesive labels? A deep dive into the causes and practical solutions you can use right away!
In the die-cutting process of self-adhesive labels, round punching is one of the most mainstream processing methods. However, burr issues at the cut edges during die-cutting (i.e., uneven, fibrous, or film-like residues on label edges) have always been the number one quality "stubborn problem" troubling label printing enterprises. Burrs not only affect the appearance of labels but, in severe cases, can cause automatic labeling machines to jam, break, and poor label peeling, directly impacting end customers' production efficiency.
This article synthesizes multiple real cases, systematically analyzing the causes of burrs from four major dimensions: tools, equipment, materials, and processes, and proposes practical solutions.
Analysis of the causes of burrs
01
#刀具相关因素#
Tool wear
During continuous die-cutting operations, the blade frequently rubs against the self-adhesive material. The new blade microstructure is compact and sharp, allowing it to cut materials quickly with minimal resistance.
However, as the number of die-cutting cycles increases (for example, after over one million high-strength die-cutting cycles), the blade surface material keeps peeling off, the edge gradually becomes rounded and rough, and even tiny notches and cracks appear, greatly reducing cutting ability. This ultimately results in the material being "crushed" rather than "cut," resulting in burrs. Common solution: Replace the blade regularly and establish usage records.
The impact of tool material on wear resistance:
- High-speed steel or cemented carbide with hardness above HRC65, wear-resistant coating: can maintain sharpness for a long time.
- Ordinary tool steel with hardness lower than HRC55: rapid wear leads to burrs.
Blade angle
The size of the cutting edge angle will directly affect the final cutting effect. Practice shows:
- Small-angle (e.g., 45°-60°) cutting edge: sharper cutting and suitable for film-type materials.
- Large-angle (e.g., 75°) cutting edge: More durable but with increased cutting resistance, better suited for paper-cutting materials.
Therefore, the blade angle should match the material type and thickness.
Tool installation accuracy
Non-parallel tool installation (the angle between the blade and the die-cutting roller axis) causes uneven pressure distribution along the axis. Even a deviation of a few microns in installation parallelism can cause one side to "cut through" while the other side "cannot cut."
02
#设备因素#
Tool Roller Clearance Accuracy (Core Factor)
I have encountered a previous case where a beverage brand's bottle label material had a backing paper thickness of 0.053mm, a face material thickness of 0.130mm, and a knife height of 0.432mm. In theory, the standard gap of the knife roller should be 0.480mm, but the actual measured gap was 0.493mm, which is 0.013mm larger than the standard value.
The consequences of this are: about 40% of labels show obvious burrs, and pressure must be increased from 800PSI to 1500PSI.
The root cause is that the magnetic tool roller shoulder height does not match the clearance accuracy of the bottom roller. The gap is too large, preventing the blade edge from accurately cutting through the silicone oil layer of the backing paper. After the tool height was readjusted to 0.443mm, the product pass rate increased to over 99%.
Uneven pressure
Equipment pressure system issues:
- Surface processing defects of pressure rollers (bumps, cylindricity).
- Insufficient or loose pressure regulation device.
- Insufficient rigidity of the pressure transmission system (for example, when No. 45 steel has a yield strength of 355MPa and does not meet standards, elastic deformation exceeding 0.05mm can occur at 1000N pressure).
Bottom roller and support roller
- The bottom roller hardness is recommended to reach above 62 HRC.
- For thin backing paper products below 30μm, the support roller is crucial for ensuring accuracy.
- Wear/damage to roller shoulders can cause runout during operation.
03
#材料因素#
Batch differences
Materials of the same brand and model may have internal structural and performance differences between batches. Even if parameters such as thickness and viscosity fall within the standard range, die-cutting results can vary significantly.
For example, a case of a certain drug label:
Phenomenon: On the same production line, some batches develop burrs.
Reason: Changes in the internal structure of new material batches.
Solution: Communicate with suppliers about quality control and adjust die-cutting parameters (speed reduction, pressurization, cutting edge adjustment).
Thickness tolerance
The standard tolerance for Glassine backing paper is ±0.002mm. Exceeding this range will directly affect the consistency of the die-cutting depth.
- Thicker areas: cut through the backing paper → break the paper.
- Thin areas: cannot cut through → rough edges.
Viscosity strength
Material viscosity (such as 500g/25mm coated paper) affects the force during cutting; excessive viscosity increases cutting resistance.
04
#工艺参数#
Die-cutting speed
Case of an electronic product label:
- Speed below 60m/min: Die-cutting quality is good.
- Speed increases to 80-100 m/min: burrs begin to appear.
- Cause: At high speeds, the contact time between the blade and the material shortens, the impact force changes, and the cutting shifts from "shearing" to "tearing." When the new blade is sharp, it can cut; if the edge is not sharp, it will become a compressed material. If the breaking time is too short, the material breaks less completely.
- Solution: Control speed below 60m/min or match with a better tool.
Pressure setting
Pressure settings must precisely match material thickness and tool height. Insufficient pressure leads to incomplete cutting; Excessive pressure not only wastes resources but may also damage the equipment.
Systematic resolution strategies
1. Tool management
Material selection: preferably HRC65+ high-speed steel or cemented carbide, with coating or coating processes.
Cutting Edge Angle: Film 60°-65°, Paper 70°-75°.
Replacement cycle: Establish blade usage records and issue warnings based on the number of die-cutting cycles.
Installation accuracy: Parallelism is controlled at the micron level, and the tool marking's calibration line coincides with the roller calibration line.
2. Equipment maintenance
Gap calibration: Regularly check for wear to ensure the gap = backing paper thickness + tolerance.
Pressure system: Recommended gauge-type hydraulic pressure rod, high precision and visualization.
Roller shoulder maintenance: keep clean, lubricate regularly, and check for wear.
Support rollers: Thin backing paper (<30μm) products must be configured.
3. Material control
- Require suppliers to provide batch consistency reports.
- Trial cutting and verification before each batch of new material goes online.
- Focus on the thickness tolerance of the backing paper (≤±0.002mm).
4. Process optimization
- Speed matches the tool (high-speed tools should be paired with higher hardness and sharper tools).
- Pressure adjustment: Gradually adjust pressure from low to high to avoid excessive pressure.
- Temperature and humidity control: temperature ≤ 25°C, humidity ≤ 50%.
In summary, burr issues may seem minor, but they actually involve complex systems engineering involving tools, equipment, materials, and processes. The solution should shift from "treating the problem" to "system diagnostics"-first eliminating the most easily inspected tool wear and installation accuracy issues, then checking equipment clearance and pressure systems, and finally optimizing material and process parameters. Only by establishing a comprehensive die-cutting quality control system can we fundamentally resolve the persistent burr problem and achieve the ultimate goal of precision die-cutting.