The fundamental steps to press optimization
In the last issue of The Flexcel, Kevin Schilling, Global Senior Product Applications Specialist, explained what goes into optimizing the platemaking operation, utilizing a five-step plate room audit. But to take advantage of the productivity benefits of delivering high-quality work consistently and cost-effectively, optimization has to extend into the pressroom. In this issue, Kevin explains why and sets out the fundamental steps to take…
More than a decade of innovations with FLEXCEL NX Technology has addressed many of the variables that previously gave traditional flexo a reputation for inconsistency. By building on features such as true flat-top dots and pixel-for-pixel (1:1) image reproduction, FLEXCEL NX Technology has eliminated the guesswork in prepress and established true consistency, enabling printers to rely on more predictable press performance.
Since 2010, some of the most important enhancements of the technology have been multi-form plate surface patterning, beginning with DIGICAP NX Patterning (single form patterning) in 2010, NX Advantage with Advanced Edge Definition (double form patterning) in 2016, and PureFlexo™ Printing (triple form patterning) in 2021 – accessed through the FLEXCEL NX Print Suite – printers have been given more and more control over print quality and operational efficiency on press. This is the result of in-depth understanding of how ink properties, release characteristics, plate properties and press factors like impression level and anilox volume affect the print quality and operational efficiency of the printing press.
But, getting the most out of multi-form surface patterning depends on having an optimized press. Optimization becomes even more important as printers go beyond CMYK and adopt modern printing methods such as ECG printing. PureFlexo Printing provides the consistency and control needed to overcome the added complexity that comes with ECG printing.
Press optimization means balancing and standardizing the performance of the various components of the printing process to produce the precise, repeatable print that color management depends on, and brands insist on. Optimization involves more factors than we can share here, but there are essential factors that are the fundamental steps needed to run an optimized press.
Run a clean, regularly serviced press
Just as in the plate room, optimization in the pressroom starts with regular service, at least annually. A clean production environment isn’t just a sign of a conscientious printer; like a restaurant kitchen, it helps operations run smoothly. Placing preventative maintenance and cleaning within your print schedule is a fundamental way to make sure this is accomplished. It also creates a mindset across teams where process control can flourish.
Look after cylinders, rollers and sleeves
The condition of cylinders, rollers and sleeves is a critical factor in optimization – they need to be close to perfectly round – so impress on the press crew how important it is to handle them with care. Roundness is expressed as Total Indicated Runout (TIR) – a measure of the radius of the cylinder/roller/sleeve from the center to the outer surface. Having a dial indicator with a magnet mount near your plate mounting equipment is an easy way to implement this check. Out-of-roundness of a couple of thousands of an inch will produce print defects and require repair or replacement.
Monitor anilox roll wear
Choosing the correct anilox volume for the screen count is important, but over time the friction generated by twin steel blades running in high-speed contact with the ceramic surface of the anilox causes wear and impacts on volume. Remember that a good ratio for anilox cell count to plate line screen is six to one; it doesn’t have to be exact but close. For example, with a 150 line screen you will most commonly see 900 to 1000 CPI in use. It is possible to adjust pigment load to compensate for wear, but eventually this is no longer possible as the ink film becomes too thin. Typically, a fall in volume of 15% indicates that the roller should be resurfaced. So, it is important to put in place a program to measure and inventory anilox rolls, either through your internal quality control procedures or with your anilox supplier.
Calibrate servo motors
Establishing and maintaining the correct nip point speed is important for getting the most value from multi-form plate surface patterning, and the nip point speed depends on correct calibration of the servo motors driving the print stations. For an analogy, consider what happens when you press a fingertip on your skin and move it from side to side. If the nip point speed is wrong something similar occurs when the plate meets the substrate, causing friction and heat.
Higher pressure typically causes higher dot gain, which reproduces a smaller tonal range. Because the nip point speed – and hence the pressure on the plate – are determined by the mounting tape pressure, optimization involves establishing the speed and pressure that provide the best dot gain, density and plate wear characteristics, extending the tonal range.
Patterns call for lower viscosity inks
The excellent ink transfer that is a hallmark of FLEXCEL NX Technology depends on more than just optimizing the correct line screen with highlight treatments to the correct pattern. Ink viscosity is another important consideration when optimizing the press to print using plates with multi-form surface patterning, especially the micro-channel patterns used in PureFlexo Printing. As remarkable as PureFlexo Printing is, capable of achieving densities at much lower pressures and with much wider latitude on press, you still need to optimize the press, because if the ink is too viscous it will not flow efficiently into the channels. Thinner ink films mean that adjustments will also need to be made to the dry rate. To learn more about how patterns help optimize print performance, see Your Pattern = Your Productivity.
Optimization also means ensuring that the specific FLEXCEL NX target densities for CMYK – 1.1 (yellow), 1.45 (magenta), 1.55 (cyan) and 1.65 (black) +/- 0.05 – are maintained on the press to control gain, density and color reproduction. The best way to achieve this is to have the ink blended so that at running viscosities they achieve the required density. On modern presses you can expect automated process control of ink viscosity and temperature.
Miraclon is here to help
The fundamental steps are essential to achieve an optimized printing workflow. And remember that comprehensive application support is available through Miraclon’s Technical Support teams, who are available to design and implement optimization programs based on your specific needs, helping you complete these steps in your pressroom.
Pressroom audits are included as part of a Miraclon Technical Support Plan to ensure you are running as efficiently as possible. Remote audits are a great option for fitting an audit into a hectic schedule: For more information on remote audits see Remote audits: support when you need it or contact your local Miraclon representative to schedule your audit.
Kevin says:
“Optimization means balancing and standardizing the performance of the various components of the printing process to produce the precise, repeatable print that color management depends on, and brands insist on.”