Specification for Installation, Maintenance And Care of Ceramic And Metal Anilox Rolls

1.Purpose

Ceramic and metal anilox rolls are high-tech products and very expensive precision core components of flexographic printing equipment. They feature high dimensional accuracy, geometric and positional accuracy, surface roughness, and dynamic balance accuracy.Therefore, this specification for the installation, maintenance and care of ceramic and metal anilox rolls is specially formulated. All flexographic printing positions are required to strictly implement and accurately operate in accordance with this specification.

Proper, timely and scientific daily maintenance of ink-transferring anilox rolls can prevent roller damage, extend their service life, and achieve stable and high-quality printing results.

2.Scope

This specification applies to the installation and maintenance of all ceramic anilox rolls and metal anilox rolls in flexographic printing equipment.

3.Terms and Definitions

3.1 Ceramic and metal anilox rolls:Including ink anilox rolls and varnish anilox rolls.

3.2 Storage:Including storage of new anilox rolls and storage of removed anilox rolls to be repaired.

3.3 Hard tools:Tools with hardness higher than HRC 20, excluding knocking tools made of rubber, wood, copper, etc., used for installation.

3.4 Test run: Trial operation before formal startup and production.

3.5 Service outer diameter range:Refers to the allowable outer diameter range of the anilox roll during use.The designed service outer diameter range varies with different equipment.Exceeding this range will render the roll unusable: an oversized diameter will cause interference with mating components, while an undersized diameter will be out of the applicable range.

4.Operation Process and Maintenance Requirements

4.1 Installation:During the installation and use of anilox rolls, direct striking with hard tools, collision with hard objects and scratching are strictly prohibited.

4.2 Storage:

(1) The storage cases for ink anilox rolls shall be kept indoors in a dry placeto prevent damage caused by moisture, rain and direct sunlight.

(2) When replacing anilox rolls, protect the roll surface carefully and strictly prevent damage caused by collision, extrusion or friction.Anilox rolls that have finished working must be cleaned thoroughly and in a timely manner.Do not store unclean or undried anilox rolls.Ceramic anilox rolls shall be wrapped with packaging foil made of natural fibers before being placed into the storage case.

(3) Anilox rolls not stored in cases shall be fixed on special storage racks to ensure the roll surface is suspended.It is strictly prohibited to place the rolls directly or obliquely on the ground, so as to avoid damage to the ceramic coating, hard chrome plating and cells on the anilox roll surface.

4.3 Lifting & Handling

(1) Do not fasten the lifting rope directly onto the anilox roll surface for lifting or moving, so as to prevent the roll from slipping or being damaged due to loss of balance during lifting and moving.The correct method for moving the roll is to fix the lifting belt or other supports on the shaft heads at both ends of the roll, and avoid contact with the roll edge or other parts of the ceramic coating.

(2) Lifting shall be light and slow, and movement shall be stable. Large amplitude shaking or swinging is strictly prohibited.

4.4 Replacement and Repair:Due to different designs from various equipment manufacturers, the allowable outer diameter range of anilox rolls varies, so the number of repairable times is limited. For this reason, a roll record file shall be established to facilitate operation and maintenance management.

(1) A repairability assessment must be performed before each repair to avoid incorrect repair of rolls with excessively small dimensions, which would render them unusable.

(2) Dimensions for replacement and customization must be within the designed maximum service size range to prevent installation failure due to interference.

4.5 Test Run and Startup ：Operation may only start after the following items have been verified and confirmed error-free before test run and each startup.

(1) The pressure between the anilox roll and the doctor blade or rubber doctor roll shall be adjusted to be uniform.

(2) The gaps between the anilox roll and the plate roll, as well as between the plate roll and the impression roll, shall be adjusted to a reasonable value, ensuring consistent gaps across the entire roll surface.

(3) The working accuracy of all adjustment mechanisms shall be accurate and reliable.

(4) All roll surfaces and doctor blades shall be clean and free of foreign matter.

(5) The circulating ink supply system shall function normally, and the ink shall be reliably filtered.

4.6 Inspection and Cleaning

(1) The anilox roll must be carefully inspected and cleaned before each use to ensure that the anilox surface is free of oil, grease and dust. 

(2) Regularly inspect the cells of the anilox roll with a cell microscope. If wear or blockage is found, take timely measures. 

(3) After each printing run and before changing ink, the surface of the anilox roll must be thoroughly cleaned in time to prevent residual ink from drying at the bottom of the cells and gradually blocking them.

                                                                                  (Blocked cells)                                                                          (Clean cells)

Water-based ink has the following water-resistant characteristic: it is soluble in water before drying, but becomes insoluble in water and ink after drying.Once residual ink dries at the bottom of the cells, it is difficult to clean effectively. Over time, the buildup will increase, reducing the effective volume of the cells and lowering ink transfer, which directly affects printing quality.Therefore, do not stop rotating the anilox roll during job breaks to prevent the ink inside the cells from drying and blocking the cells.

(4) When cleaning the anilox roll, the doctor chamber and pipes shall also be cleaned. For daily cleaning, a water-soluble cleaning agent (washing fluid) can be used for circulating cleaning on the machine first, followed by clean water rinsing.The cleaned anilox roll must be dried and separated from the doctor blade or rubber doctor roll to prevent residual water stains at the contact area from drying inside the cells.

Water stains left without drying after cleaning 

4.7 Measures to Prevent Scratches on Ink Anilox Rolls

(1) Causes of scratches on ink anilox rolls

(Cells worn in scratches)

When dry aggregates such as dust particles, dried ink or varnish residues from the printing plate, equipment top plate and paperboard, as well as fine metal particles shed from a damaged doctor blade, etc., are mixed into the ink, they will become trapped between the doctor blade or rubber doctor roll and the surface of the ink anilox roll.

During high-speed rotation in printing, these trapped hard objects cause severe friction against the anilox roll surface, the doctor blade or the rubber doctor roll. Over time, this results in circumferential linear wear and scratches on the ink anilox roll and the rubber doctor roll.

                                                                (Rubber Roll Ink Doctoring System)                                                           (Doctor Blade Inking System)

If hard particles fall between the rubber roll and the anilox roll, they will first grind a groove into the rubber roll until the particles fall out of the enlarged groove. At the same time, a corresponding circular worn bright line will also be formed on the anilox roll.

Once the hard chrome layer of a metal anilox roll is worn, the first worn spots will rust in a pitting pattern and gradually spread.Therefore, when grooves appear on the rubber roll and bright lines appear on the anilox roll at the corresponding positions, timely inspection and treatment must be carried out, and ink filtering measures must be taken.

(2) Before printing, remove dust and impurities from the surface of the printed product and keep the printing area clean.Adjust the contact between the dust removal brush before the first color and the printed product to the proper position in a timely manner.Adjust the air inlet position and air volume of the dust removal fan properly to ensure timely and reliable dust removal,and prevent hard particles from entering the printing area with the paperboard and falling onto the printing plate and ceramic roll.

(3) After printing is completed, timely remove ink splatters and dust on the machine and restore the cleanliness of the printing area.

(4) Do not rotate a dry ink anilox roll while it is pressed against the doctor rubber roll or doctor blade, so as to avoid damage.

(5) Do not apply excessive pressure to the doctor blade or doctor rubber roll in order to obtain more color tone,as this will increase wear on the anilox roll, doctor blade and doctor rubber roll.

(6) Each time a new doctor blade is replaced, the pressure must be reset. Incorrect pressure setting will produce blade fragments and damage the surface of the anilox roll.

(7) When installing a new doctor blade, inspect the wear condition of the old blade edge. Identify and eliminate the causes for uneven blade wear. Clean away ink residues and dust on the mounting surface to ensure the straightness of the new blade edge, keeping it parallel to the anilox roll with uniform pressure.

(8) Stop using doctor blades that have exceeded the maximum wear limit. Establish a daily management system to monitor blade wear, so as to stably control the wear degree of the doctor blade and avoid damage to the anilox roll.

(9) Always keep the anilox roll surface parallel with the doctor blade. The doctor angle and parallelism between the roll and the blade must be inspected and calibrated every 15 days.

(10) Maintenance of the doctor blade system:Open the doctor chamber before each ink change, clean it thoroughly with water, then wipe the chamber and the doctor blade with a clean cloth.Ensure no ink residues, sand particles or other deposits remain adhered inside the doctor chamber.If such deposits fall off, they will become trapped between the doctor blade and the anilox roll surface.During printing, high-speed rotation causes these trapped hard particles to rub violently against the anilox roll surface, resulting in wear and scratches on the roll and damage to the doctor blade.Therefore, all ink residues and impurity particles in the doctor chamber must be completely removed.

(11) A magnetic filter may be placed in the ink tank to remove metallic impurities and prevent them from scratching the anilox roll surface.

(12) The use of inferior ink containing filler impurities is prohibited, to avoid damage to the anilox roll, doctor blade or doctor rubber roll.

(13) Water-based ink and printing water must be filtered. A dedicated magnetic filter may be installed at the ink intake pipe inside the ink bucket.

Ink Magnetic Filter

Install a special water-based ink filter at the return ink pipe where the ink circulates back into the ink bucket, which can effectively remove paper fibers and impurity particles continuously mixed into the ink.

(14) The floor around the printing press shall be frequently washed with water to prevent dust particles on the dry floor from being blown onto the anilox roll by wind.During operation, these dust particles will become trapped between the doctor blade / doctor rubber roll and the anilox roll surface, causing damage and scratches to the anilox roll due to high-speed friction.

In the next section, we will explain in detail various cleaning methods for anilox rolls.