Industry News

In the flexographic printing industry, lines that are lighter or darker than the rest of the printed area occasionally appear on the finished product such as coffee paper cup, popcorn paper cup, Hamburger wrapping paper, shopping bag, sterilization pouches, baby diaper and so on. These are uneven printing effects caused by anilox scoring. In a flexo printing press, the anilox roller is one of the most core and expensive components. However, a little carelessness can cause damage to it. Anilox scoring are one of the most difficult and most expensive quality issues of the anilox roller. So, what are the types of anilox scoring? What are the causes of anilox scoring? How to prevent anilox scoring? This article will explain these 3 aspects.

Anilox Scoring in Printing

What Are the Types of Anilox Scoring

By observing the printed product, anilox scoring can be roughly divided into two types: light streaks appearing in the printed area are called light scoring , while dark streaks appearing are deep scoring.

Deep Scoring

Deep scoring occur when the ceramic layer of the anilox roller is severely damaged. Generally, when the operator of the flexo printing machine applies too much pressure to avoid ink leakage, the tip of the doctor blade scrapes the ceramic surface of the anilox roller, damaging the engraved pits on its surface, which causes the anilox scoring. As a result, more ink is delivered to the damaged engraved area of the anilox roller, and the color caused by this anilox scoring is darker than the color of other areas on the printed products. In addition, the generation of deep scoring is also a factor that leads to ink waste.

Deep Scoring

Light Scoring

Light scoring is most common in flexographic printing and appear as light streaks on the finished print. Therefore, in the area where the light scoring are located, the print will either have no ink or very light ink. Light scoring are caused by a piece of foreign matter getting stuck on the anilox roller, which will brush off the top layer of the anilox roller. This will then cause less ink to be carried in that part of the anilox roller, resulting in light streaks or no ink on the finished print products such as bed sheets, surgical gowns, ice cream bowls, lazy rags, takeout paper bags, beverage bottle labels, etc.

Light Scoring

What Are the Causes of Anilox Scoring

To understand the root cause of anilox scoring, it is necessary to consider a variety of issues related to the anilox roller. When the causes of anilox scoring are fully understood, operators can prevent anilox scoring in future print production and avoid the costly losses caused by high maintenance fees and downtime for repairs.

Ink Particle Build-Up During Ink Metering

Generally speaking, anilox scoring is usually formed during the ink metering process, at the contact point between the doctor blade and the anilox roller. This is because hard particles are stuck between the doctor blade and the anilox roller. Smaller particles may scratch the ceramic surface of the anilox roller, causing anilox scoring, resulting in light streaks on the printed product.

Inline Type Flexo Press

Excessive Braking Force

In addition, excessive braking force applied by the operator is also an important reason for the anilox scoring. The braking pressure will interfere with the normal operation of the doctor blade and damage the engraved layer of the anilox roller. The operator applies excessive braking force to reduce problems such as position deviation, ink leakage or mechanical vibration. Due to the excessive braking force applied, the tip of the doctor blade falls off, resulting in anilox scoring. 

Stack Type Flexographic Printing Machine

Particles Stuck in the Ink System

Sometimes, over time, small particles, impurities and other fine materials can get stuck in the ink system such as ink pump, ink tray and so on. In normal operation, the ink system can easily deliver these particles to the contact point between the doctor blade and the anilox roller, scratching the surface of the anilox roller and forming anilox scoring. In addition, these particles may cause the doctor blade tip to break, causing more ink to overflow. This will cause dark streaks on the printed product.

Central Impression Flexo Printer

Doctor Blade Holder Misalignment

In flexographic printing, each doctor blade is designed to work with a specific anilox lpi. Therefore, when replacing the anilox roll, it is essential to realign the doctor blade accordingly. Likewise, when an old doctor blade is removed and replaced with a new one, the doctor blade holder must also be properly realigned. Failure to realign the doctor blade holder in a timely manner may result in surface damage to the anilox roll, leading to anilox scoring.

Stacked Flexo Printing Equipment

How to Prevent Anilox Scoring

Anilox scoring repair and roller replacement are costly. Preventive steps—such as regular cleaning, optimizing ink properties, proper braking force of doctor blade, and correct blade alignment—can help avoid anilox scoring.

Regular Cleaning of the Anilox Roller

Regularly perform periodic deep cleaning of the anilox roller to remove any trapped fine particles within the engraved cells. Use proper cleaning methods and suitable cleaning agents to ensure the anilox cells remain clean, preventing ink drying and the buildup of contaminants.

Optimizing Ink Properties

Use appropriate solvents and retarders to control the ink drying speed and prevent blocking caused by excessive drying.

Water-Based Ink for Vertical Flexographic Printing Press

Proper Braking Force of Doctor Blade

Excessive braking force of doctor blade can break the blade, causing metal fragments that damage the anilox roll’s ceramic surface and lead to scratches on the print. It is recommended to apply appropriate braking force.

Correct Doctor Blade Alignment

Misaligned doctor blades can scratch the anilox roll's engraved surface. Ensuring proper chamber alignment during installation helps prevent anilox scoring.

In summary, anilox scoring is a very common quality problem in flexographic printing. Ink particle build-up, excessive braking force, particles stuck in the ink system and doctor blade holder misalignment can cause anilox scoring. Thereby, regular cleaning, optimizing ink properties, proper braking force of doctor blade and correct blade alignment can help avoid anilox scoring.