Central Impression Press Buyer’s Guide: Productivity vs. Cost Concerns

Set to Run

Flexo Expert’s 2300mm (100-in) Concept gearless stack press

Control, monitor, adjust, customize, yet always remember to consider all variables. That recommendation comes from Joe Burgio, president, FlexoExpert. He believes when presses are configured with productivity in mind, “The job is more than 80 percent set to run, before the press moves.”

He explains, “FlexoExpert designs and constructs presses based on what a customer needs vs. a standard catalog item. For us, customization to best match the work is part of the press construction concept. Each press can be tailored individually to the customer’s needs—not chosen from a standard catalog item.”

“Print properly, automatically”—that is the principle around which Joe builds his list of essential considerations in buying a press. It includes:

  • Automation—offer easier and quicker operator handling, and minimum material use
  • Pressure—active software controlled sensors automatically preset and control printing pressure on all units simultaneously, before the job runs, and continue monitoring and making precise adjustments on the run
  • Registration—come to register in 15-ft., thanks to automatic settings. Hold it, too. FlexoExpert relies on “one-revolution register”
  • Control—look to adjust on-the-fly to account for job-to-job differences in tape and plate thickness and wear, stock thickness, etc.
  • Size—for mid web solutions, the Compact is really This press model features 8-color machines that are only 6-ft. high at the top print units
  • Customization—a “standard” part of the construction (think web widths and repeats)
  • Waste reduction—ties to faster job change and quicker setup procedures
  • Speed—match run speed with job requirements. The highest speed possible is not necessarily the most applicable
  • Finishing options—with more than 35 years of experience in custom UV equipment manufacturing, FlexoExpert’s sister company, Aradiant, can fit both LED and unique multi-patented cooler arc lamp UV systems to all machines
  • Pricing—individualized presses are still priced competitively to standard catalog offerings

“FlexoExpert’s press lineup includes five press series, from the 24-in. Compact CI through to the 2300 100-in. Concept Gearless Stack,” Joe reports. “FlexoExpert uses Indramat servos, complete sleeve technology, single-revolution register, various unwind and wind options, downstream and upstream print units, etc. One major highlight is its A3P automatic print pressure system.”

Stressing differentiating factors, Joe says, “Typical pressure setting control systems, found on other machines, work by using stored settings from previous jobs, and/or video cameras to set pressure and are part of a setup procedure. The weakness in those systems is that they rely on previously stored information from the control system, and/or video camera input the operator must judge to adjust print pressure. There is no consideration for variations in tape, plate thickness/wear or stock thickness changes. The A3P system takes into account theses variables and actively adjusts to print properly.”

Bearings & Benefits

The greater the rigidity of plate cylinder and anilox roll bearings, the lower the tendency to vibrations, specifically with demanding print designs, reflected in the Bobst 20 Six CS press.

“To ensure process consistency, a press should be equipped with automatic systems that correct the printing position dependent on speed, that control the temperature of the CI drum, and that compensate for dimensional variations of the side frames,” according to Todd Blumsack, vice president, business unit web-fed, Bobst North America Inc.

“User-friendly handling concepts should facilitate calibration at regular intervals.” He continues, “Modular design drying systems allow for adapting the dryer capacity to specific production requirements.”

Blumsack lists out essential considerations in two groups, with the first five relating to print quality and numbers six to 10 tied to productivity.

Related to print quality:

  • Rigid design of the cylinder bearings—rigid bearings are key to the performance of a press in terms of print quality
  • Highly sensitive impression adjustment capability—flexo printing is a highly sensitive process, particularly in regards to impression setting and ink transfer. This means all the components involved in printing must be designed for precision in the micron range—both mechanically and in terms of control engineering
  • Guaranteed process consistency—once set, the perfect printing position must be maintained throughout the entire process
  • Calibration of print units—to ensure consistent print results across the whole working width, tools should be available that allow for calibrating the print units at a precision in the micron range
  • Guaranteed drying for all applications and speeds—floating and impingement-type nozzle technology, optimized air flow, and the use of recycled air are features of a state-of-the-art drying system that ensures the drying of ink even at high speeds

Related to productivity:

  • Minimizing waste—there are systems on the market that perform all registration and impression setup fully and automatically. The efficiencies of such systems, however, vary considerably. There are systems that do all the setup off press, during the mounting stage, and generate zero waste (of substrate, inks, machine time, etc.) during changeover
  • User-friendly maintenance—for all routine maintenance jobs, the machine should allow for user-friendly access, ideally without tools required. For troubleshooting, the machine control systems should be prepared for online access through a safe internet connection
  • Fast changeover capability—user-friendly handling concepts for tool changes and automatic wash-up systems are key to fast changeovers. If the weight of the tools allows for manual changes, simple manual systems and procedures are faster than robotic systems. Super-wide machines require robotic systems up to fully automatic logistic systems
  • After-sales service capacities—if a machine supplier has a global service network in place, this ensures fastest support in case of problems
  • Financing solutions—customized to expenditure, need, preference