Two Anilox Volume Readings Do Not Match? Compare the Measurement Method Before Rejecting the Roller

Identify the roller and the measurement basis first

Start with the roller identity rather than the volume number. Match the serial number, construction, working face, engraving type, line count, nominal volume, manufacture or refurbishment date and the unit used on each report. Confirm whether the certificate belongs to the complete roller, a sleeve or one band of a trial roller. A correct-looking value attached to the wrong serial number is not process evidence.

Record the measurement system, software or configuration, lens or magnification where applicable, test-fluid or impression method, operator, date, roller temperature and whether the surface was clean and dry. If the report does not state the method, ask for it. Flexographic Technical Association reporting on anilox volume measurement explains that different historical methods and reference points can produce different stated volumes even when documents appear to describe comparable engravings.

Keep units unchanged until their basis is understood. Do not treat a converted number as comparable merely because both reports now display cm3/m2 or bcm. The method, cell geometry, calibration and calculation still matter. Use the original certificate as the incoming reference and keep every later audit under the same serial-number record.

Separate application-oriented volume from geometric volume

Zecher describes two systems on its current measuring-systems page. VoluCheck applies a defined quantity of standardised test ink, doctors the surface in an application-oriented process and calculates actual scoop volume from the liquid amount and covered area. Dotscope records layered images of the engraving, builds a three-dimensional cell model and calculates a theoretical geometric scoop volume.

The two results are influenced by different factors. Zecher lists surface topography, roughness, surface tension, fluid rheology and doctoring among the influences on actual scoop volume. Geometric volume depends on topography, the calculation algorithm, cell geometry and the web portion. Zecher therefore states that the two methods are not necessarily comparable. A difference between them is not, by itself, proof of wear or blockage.

Use each method for the question it can answer. An application-oriented reading can support a transfer-capacity reference when its materials and procedure are controlled. A geometric system can document cell shape, depth and calculated volume when its optical and software settings are fixed. Do not choose whichever result is closer to the target and ignore the other. Record the method beside every number in the anilox inventory.

Create a like-for-like condition trend across the working face

Clean the roller through the approved chemistry and handling procedure, rinse and dry it, then allow it to reach the measurement condition required by the method. FTA notes that temperature and evaporation can affect liquid-volume testing. A reading taken immediately after a warm cleaning process should not be compared casually with a room-condition certificate.

Measure the same marked positions across the operator side, centre and drive side, avoiding damage or contamination introduced during handling. Zecher's inspection information describes using several points, including repeated readings on the right and left of a roller. A cross-face pattern is more useful than one average when colour strength or coating laydown also changes by lane.

For repeated Dotscope analysis, Zecher says identical measurement settings are essential for comparability. Apply the same principle to any plant method: same instrument, calibration routine, settings, sampling map, surface condition and reporting units. Keep the individual readings as well as the average. An average can hide one plugged band, local wear or a damaged area that affects only part of the web.

Connect the report to a controlled press result

Before condemning the roller, reproduce the job standard under controlled conditions. Record the press and station, substrate, ink or coating identity, temperature, viscosity or pH where applicable, chamber and blade setup, speed, impression, drying or cure and the measured colour, opacity, coating weight or other required result. Volume is one part of the transfer system, not a substitute for the finished-product requirement.

If the press result has fallen, separate the likely causes. Confirm ink condition, doctoring, chamber flow, contamination, surface damage and cleaning history before calling the difference wear. Compare the current cross-face map with the original certificate using the same method where possible. A blocked roller may respond to an approved deep-cleaning process; a worn or damaged engraving needs a different disposition.

Use a banded or controlled press trial when selecting a replacement engraving or changing the standard. Keep ink, substrate, speed, plate, chamber and measurement method fixed while the engraving variable changes. Approve the specification from the required print or coating result and the complete operating window, then save the accepted sample, certificate and test conditions together.

For a Royal Coat review, send the anilox serial number and both complete reports, measurement methods and settings, cross-face readings, cleaning and service history, current press conditions and labelled samples from the accepted and failed production. Those records allow the measurement difference to be interpreted before a roller is cleaned, remeasured, repaired or replaced.