Standard Engraving Specs for Print Applications
In narrow web flexographic printing today with machines capable of such fast speeds; concentricity and consistency can be maintained reducing the variables, which allows the printer a greater selection of substrates and ink types for their particular applications. With all these changes, the narrow web printer is still able to perform with a minimal number of Anilox Roller engravings (or screen counts). The following can be used as a guide to anilox selection in the industry today.
GENERAL PRINTING – 360
Covers day-to-day printing, some fine line, some reverses and solids. Recommended and inventoried by most press manufacturers for the most generous versatility.
FINE PRINTING ENGRAVINGS & PROCESS – 600
The 600 LPI is most recommended and inventoried by press manufacturers for its versatility in fine screen printing. It can handle a variety of solids with good success. The printer most usually establishes the engraving needs based on the equipment and capabilities. The screen count used for the Anilox will usually run doctor blade. There are applications using up to a 90 Durometer rubber roll.
200 to 360 LPI is good for large solids where color is important for total coverage, etc. where a good grade paper is used, also for U.V. coatings. 165 LPI is used for more absorbent papers where detail is not as important. Both screens have had success with U.V. coatings depending upon the shear point of the coating from the manufacturer. Both screens have had success with varnishes.
100Q & 85Q chrome – where heavy coatings ¾ mil, ½ mil, etc, are necessary in narrow web. These applications are recommended as chrome anilox rollers, guaranteeing a 100% release of solution. And since chrome rollers are half the cost of ceramic, they are easier to expend than a ceramic anilox roller. These screens are capable of throwing the solution out of the pan as well as challenging the drying systems.
This coating today is applied thru as many different screen counts as ink, from ceramic to chrome and 120P Screen to a 200P Screen, the factor seems to be the shear point of the solution and not the viscosity. The rule of thumb seems to be if you receive a cockle finish, get more volume from your Anilox Roll.