What is the effect of the humidity of the corrugated cardboard sheet on its printing in the flexo printing machine?

The humidity of corrugated cardboard sheets has a significant impact on their performance during flexo printing. Here’s an explanation of the effects and solutions:

Effects of Humidity on Flexo Printing:

1. Low Humidity (Dry Sheets):

Issues:

• Dry sheets become brittle and prone to cracking during the feeding and printing process.
• Reduced elasticity of the cardboard can cause uneven ink transfer, leading to poor print quality.
• Increased chances of dust generation, which can clog the anilox rollers and affect ink distribution.

Impact:

• These factors can lead to misregistration, weak colors, and damaged sheets during printing.

2. High Humidity (Moist Sheets):

Issues:

• Excess moisture makes the sheets softer, reducing their dimensional stability.
• Warping or curling of sheets can cause feeding issues in the flexo printer.
• Excess water content can dilute the ink, resulting in blurred or smudged prints.

Impact:

• This can lead to jams in the machine, poor print clarity, and production delays.

Methods to Address Humidity Problems in Flexo Printing Machines:

1. Humidity Control in the Environment:

• Maintain the workshop’s relative humidity at 55-65% to ensure optimal sheet performance.
• Use humidifiers or dehumidifiers depending on seasonal variations.

2. Preconditioning of Cardboard Sheets:

• Store sheets in a controlled environment before printing to stabilize moisture levels.
• For dry sheets, use air humidifiers or lightly spray water on the surface to restore moisture.

3. Machine Adjustments:

• For dry sheets:

Reduce feeding pressure to avoid cracking.

Increase the softness of the printing blanket for better ink transfer.

• For moist sheets:

Adjust the feeding system to handle warped sheets.

Use higher-viscosity inks to prevent smudging.

4. Advanced Solutions:

• Install pre-heating or pre-conditioning units on the flexo printer to balance moisture levels during feeding.
• Use anti-static brushes to minimize dust issues caused by low humidity.

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