Understanding the Causes and Solutions for Corrugated Board Cracking in Dry Seasons

Understanding the Causes and Solutions for Corrugated Board Cracking in Dry  Seasons

The Importance of Maintaining Board Quality

Corrugated carton boxes play a vital role in global packaging industries, with their production intricately linked to the quality of corrugated boards. However, during autumn and winter, dry weather conditions lead to reduced moisture content in corrugated boards, resulting in a common issue—board cracking (commonly referred to as “seam/creasing broken”). This issue poses significant challenges for carton factories, as it can compromise box strength, aesthetic quality, and overall customer satisfaction.

In this article, we’ll explore the factors causing board cracking, strategies to mitigate these problems, and how our advanced carton-making machines can assist carton factories in achieving superior board quality.

Section 1: Why Does Corrugated Board Crack?

1. The Root Cause: Low Moisture Content

The primary reason behind board cracking is the low moisture content of corrugated boards. When the moisture content decreases—especially below 8%—paper fibers shrink, resulting in reduced flexibility and increased brittleness. This decline significantly affects tensile strength, impact resistance, burst strength, and folding endurance, leading to cracking during processing.

Key thresholds for moisture content:

• High-quality kraft paperboard (100% virgin wood pulp): Cracking occurs when moisture drops below 6%.
• Recycled fiber board: Moisture content should ideally remain above 8–9%.
• Boards made from short-fiber recycled pulp: Moisture below 8% increases cracking risks.

2. Impact of Paper Type and Strength

Different paper types and their fiber compositions affect the likelihood of cracking:

• Kraft paperboard (from long-fiber softwood pulp) has better flexibility and is less prone to cracking compared to hardwood pulp-based boards.
• Higher basis weight (thicker paper) can paradoxically reduce plastic deformation ability, increasing cracking risks.

3. The Role of Board Thickness

Thicker corrugated boards are more prone to cracking during creasing or folding. The displacement caused by compression at the surface and inner layers of the board increases with thickness, particularly when moisture content is low.

Section 2: How to Minimize Board Cracking

1. Strictly Control Moisture Content

• Warehouse Management: Maintain relative humidity in storage areas between 65–75% using humidifiers, especially in dry seasons. Seal windows and doors to prevent external air from reducing moisture levels.
• Preheating and Processing: Adjust preheating and running parameters on production lines. For overly dry boards, increase glue application or add water mist during preheating to restore moisture.

2. Optimize Dryer Temperature and Line Speed

Match drying cylinder temperatures with line speeds based on board thickness and paper quality. Avoid prolonged storage of semi-finished boards, as excessive drying can lead to moisture loss.

3. Adjust Paper Selection

Choose paper grades suitable for seasonal conditions. For dry weather, prioritize flexible and high-moisture-content Kraft paper to improve performance. Additionally, reducing the number of corrugation layers (if feasible) can minimize board thickness and lower cracking risks.

4. Implement Technical Upgrades

• Add spraying or coating devices to increase moisture content on low-moisture paper.
• Install a humidification system before slitting and scoring processes to mitigate micro-cracks.
• Wrap creasing wheels with sponge strips or apply adhesive to protect fragile board edges.

Section 3: Handling Low-Moisture Boards

If corrugated boards with low moisture content must be used, consider these measures:

1. 1. Humidification Treatment: Place boards in a sealed room with a humidifier to allow moisture absorption. For small batches, wipe the boards with a damp cloth to improve moisture levels evenly.
   2. Adjust Creasing Wheel Pressure: Calibrate the upper and lower creasing wheels to reduce pressure, allowing boards to deform without cracking.

Conclusion: Ensuring Success in Dry Seasons

Board cracking doesn’t have to be an inevitable challenge for carton factories during dry seasons. By understanding the root causes, implementing effective strategies, and investing in advanced machinery, factories can achieve consistent product quality and maintain customer satisfaction.

Source by : Moss (Carton Making Machine📦Flexo Printer Slotter FFG)