A variable with a great impact on your flexo forms is the Anilox Roll BCM (Anilox ink transfer volume).
The contribution capacity of the Anilox roller is an important factor in the results of the prints. Therefore, the BCM for flexo it is a variable that must be controlled to optimize ink transfer during the printing process.
What is BCM of Anilox roller?
It is a measure of the volume of ink transfer from the Anilox roll to the photopolymer, expressed in trillion cubic microns per square inch (billion cubic microns per square inch in its acronym in English) – BCM / in².
For more context of these units of measurement, a cubic micron (μm³) is a unit of volume and a trillion cubic microns would be 1,000,000,000 μm³.
Importance of BCM
This unit of measure is very important when making a correct choice of anilox, since a high volume of contribution can represent a great coverage of ink in printing and a low volume can represent a deficiency.
Anilox transfer volume
The importance of anilox transfer volume lies in keeping procedures in the press under control, the BCM is one of the most important in printing, which will determine the amount of ink supplied to the photopolymer for flexography.
Volume is the amount of three-dimensional space that is in a space that can be bounded, and this space has the capacity to contain or retain elements.
Anilox rollers have microscopic cells capable of storing ink for transfer to the photopolymer, the number of cells will be defined by the ruling of the Anilox, if the line of the roller is higher, there will be a greater dosage of ink. At present there are several lines that offer different transfer volumes.
Anilox Volume Range Table
The following table contains range information depending on the application you want to print (FTA standard):
If the results of your prints are not what is expected due to aspects such as the excessive dot gain, printed without color strength, poor quality, among others, the BCM of your Anilox roller may be the cause of these problems.
This is a variable that you must take into account when making a configuration on the press for printing.
The above mentioned will help you to take corrective measures and replace the Anilox with one that has the correct transfer capacity, remember that this goes hand in hand with own screen ruling.
For example, prints have different requirements based on the expected results, on the type of substrate, the screen ruling of the print, therefore, the Anilox Roll BCM must be an ally when printing to give quality results or the opposite being a total disaster.
BCM conversion calculation
One of the great challenges in printing is printing with the less ink possible, but a standard should be established for the Anilox contribution volume, so that the print does not have poor color or excessive dot gain.
There is no specific guide for you to make an exact choice of trainer. But for the choice of the anilox ruling, a ratio of 1/6 can be used, it must be at least 6 times higher than that of the plate.
You have a 600 LPI anilox. The maximum screen ruling you can use on the plate will be 100 lpi.
You want to print 150 LPI. You must have at least a 930 LPI anilox.
It is important to clarify what to choose the highest ruling will not always be the best choice, and it is directly linked to the ruling of the flexo iron.
BCM to cm³/m² conversion
The unit of measurement for the volume of Anilox rolls depends on their place of manufacture.
Rollers manufactured in the United States are expressed in their unit of measure in BCM. In other places you can find it expressed in cm³/m².
Converting between these units of measure is very simple.
For conversion, BCM to cm³/m² must be multiplied by 1.55.
2.4 BCM x 1.55 = 3.72 cm³/m²
For the conversion of cm³/m² to BCM it must be divided by 1.55.
3.72 cm³/m² / 1.55 = 2.4 BCM
Remember that all Anilox rollers are subject to verification before being replaced, in the technical sheet there is data that will help you have greater control of the roller BCM for a correct choice.