The die is cast

2 April 2019

If we look back over time in the converting industry, and in particular for the label sector, a whole host of major developments have taken place. Matthew Rogerson examines how the die-cutting sector has become an essential part of converting and continues to transform and drive future growth.

The most obvious change that has probably taken place is in the printing sector, with the switch from conventional printing technologies to digital printing. Labels were die-cut on linear, flat-bed die-cutters using steel rule dies, although the more modern presses were already using rotary die-cutting units that predominantly worked with engraved cutting cylinders.

Then, two companies, Kocher + Beck and Electro Optic, introduced major advances in die-cutting technology to the market. Developed in America Kocher + Beck brought as first company die-cutting system with magnetic cylinder and changeable flexible dies to Europe. It was a major step forward and shortened delivery times from three weeks to around a week, with costs also coming down substantially.

Germany-based rotary die-cutting specialist Kocher + Beck continues to invest in new equipment and technology. “Our goal is to meet customers’ needs today and in the future, as well as focusing on total continuous improvement to reduce waste and increase throughput throughout the production process,” says Daniel Grammatikos, chief financial officer for Kocher + Beck USA, the company’s North American division based in Lenexa, Kansas.

Kocher + Beck continues to see increased sales and interest in its magnetic cylinders and flexible die products. Grammatikos says, “Customers cite the tight tolerances that these products offer in addition to the repeatability and predictability, resulting in profitability.  Also, using our technical support team for special applications is also cited as a powerful resource.”

According to Grammatikos, Kocher + Beck has several research and development projects in the works that are expected to launch this year. “Kocher + Beck offer unparalleled service to its customers and their customer projects, along with valued product offerings based upon run needs and substrates. Customer satisfaction on industry-leading tolerances is also cited as a reason our customers continue to place repeat and new orders with us.”

In addition to supplying a full range of die-cutting and printing technology and tooling, the company supplies cutting stations such as the GapMaster, as well as automatic unwinding and rewinding systems. The GapMaster sets the gap between the stamping/magnetic cylinder and the counter-stamping cylinder in a rotation stamping system. The company’s UR Precision automatic unwinding and rewinding system ensures nonstop feeding and winding for web materials to the printing and converting machinery.

The second pioneer, Electro Optic, revolutionised die production worldwide with its ground breaking: fully automated CNC-sharpened dies. The resulting increase in quality over the hand-sharpened dies represented a quantum leap forward. The process developed by Electro Optic allowed die heights to be very precisely tailored to the die-cutting unit and it became possible to have two or three die line heights in one die for sandwich materials and for cross perforating. Worldwide, label producers continue to reap the benefits of this development.

Purchase to dream

Electro Optic was purchased in 2017 by Rotometrics, a move that underscored the prominent role being played by flexible dies in the industry.

“As an integral part of the converting process, we want to help our customers get more business,” says Keith Laako, RotoMetrics’ vice-president of global marketing and business development. “We understand there is a growing demand in the market for unique packaging solutions and an increasing need for speed and efficiency.  That is exactly why we brought together the two best tooling companies. Our combined operations offer the most innovative die-cutting technology, plus the broadest product range in the market to offer customised solutions for every converting challenge.”

Laako stresses that by joining forces with Electro Optic, RotoMetrics now offers what he says is the industry’s most extensive materials database. “We know how to cut materials better. We build our products to meet and exceed our customers’ standards for precision, sharpness and longevity. We are continually evolving our products and practices to deliver better solutions. Plus, we make house calls for on-site problem solving in the places where our customers do business to make sure we understand their challenges.

“Labels are a business built on speed,” he adds. “We built our business to be fast and responsive to our customers’ needs.  We use state-of-the-art technology to deliver optimum performance with speed that exceeds industry standards. Our streamlined supply chain precisely delivers what you need, where and when you need it. Combine all this with our uncompromising regard for deadlines and we deliver what we promised, when we promised it.”

On the Electro Optic side of the business, RotoMetrics offers the Gold Line Special flexible die that features no liner strike and what the company says is unmatched height parallelism due to Electro Optic’s patented processes. “New label materials create increasingly special demands on the precision of all components involved in die-cutting.  Successful die-cutting on ultra-thin liners without die strike can only be accomplished by keeping the tolerances within the narrowest limits.  Electro Optic’s Gold Line Special quality exactly meets this challenge,” Laako says.

Also popular among label converters within the Electro Optic product portfolio is the Dura Line flexible die, which is specifically designed to handle the most abrasive materials for longer die life and longer production runs. Electro Optic’s Dura Line coating provides surface hardness of more than 1,100 HV (in comparison: The laser hardening until 63 HRC ≈ 800 HV) protects the cutting lines against scrubbing of high gloss paper, thermal paper, matted foils, writeable colours and lacquers, luminescence inks, metallic inks, whitener and pastel colours.

Concludes Laako, “We believe our unique combination of exceptional people providing unparalleled support and reliable solutions create value and speed that are key to helping our customers succeed.”

Rise to the challenge

Over the past twenty years, label presses have increased in width for example from 180–520 mm (7–20.5”) to mention just two standard dimensions. The resulting higher demands on  the die-cutting process have largely been met  by the established die makers making  constant quality improvements. In addition, adjustable anvil cylinders offer clear advantages when dealing with differing material thicknesses delivering time-savings and enhanced production reliability.

The trend to thinner and thinner label materials and carrier films currently represents the biggest challenge. In die-cutting, the face material is compressed by the cutting tool to such an extent that it breaks whilst the silicone layer and the carrier remains undamaged. As the face materials become thinner so it becomes increasingly more difficult to cut the label material, including the adhesive, but not the other layers.

The die-cutting process is quite complex involving label face stocks, carrier materials, magnetic cylinders, anvil cylinders some with substructures as well as intermediate support rollers. Then there is the general stability and stiffness of the die-cutting unit, which can generate vibration and oscillation. All of these components must be produced within certain tolerances.

However in day-to-day production not all the components are brand new which means that concentricity deviations of 10µ are not uncommon in magnetic cylinders. Also anvil cylinders are often not rounded, or are worn on one side which can alter the magnet cylinder nip by 0.480mm, and often considerably more. PET and PP carriers of 23µ, 18µ and thinner are much less forgiving of such deviations than is the case with 35–50µ carrier materials.

This challenge can only be mastered if the die-cutting unit is constantly maintained ‘as new’ and the dies and magnetic cylinder produced with height tolerances of 2µ – which compares with the diameter of a human hair of around 30µ.

For an insight into these challenges from a die-cutter perspective, ETI’s president, Maxime Bayzelon, had thought to share “A principal challenge for label converters to obtain a perfect label relates to consistent, high-quality die-cutting at a competitive line speed, especially given the trend to incorporate thinner liners. Pressure, deflection and cylinder diameter variation due to heat represents operational issues poorly addressed by most station designs available on the market today. ETI recently patented its Pellicut die-cutting technology to resolve these issues. The design enables high speed die-cutting with absolutely no risk of die marks, even on extremely thin liner.”

Which system does he feel is most suitable for the modern single-pass label printing process? “Line speeds are limited when a laser die-cutting unit is integrated into a traditional printing press or digital printing station. Going digital means multiple, independent processes are required, which in turn adversely impacts production efficiency. Therefore, rotary die-cutting remains the most suitable solution for in-line printing. Many label converters update their flexo presses by adding state of the art rotary die-cutting modules which considerably improve performance.”

When asked for a general preference between semi rotary die-cutting and laser die-cutting he explained: “We believe in robust, reliable rotary units with no compromise on set-up time. Laser die-cutting is a good emergency solution, but a rotary technology with quick changeover remains the best solution in real-life production settings, even for short run applications. Semi-rotary solutions save on tooling cost. The key is to have a large range of rotary die-cutting tools that are compatible on each printing machine. This avoids the need for multiple cylinders.”

He concluded on the subject of laser die cutting, expressing that the main limitation with laser die-cutting is speed. “Normally, this would not be a problem since digitally printed material usually runs at slower speeds compared to traditional printing. However, long run lengths and high volume production runs introduce challenges,” said Bayzelon.  “Another limitation with this technology is control of the die-cutting depth.”

 The proof is in the print

Digital printing seen as a major new player has entered the fray and is capturing greater and greater market share. In many companies it is becoming an essential part of the label production, allowing highly fragmented and rush jobs to be handled without any problem. Laser cutting is also well suited to rush jobs as the change over from one job to the next involves no makeready time, no loss of material and no die costs. However, at present most converting lines are fitted with rotary die-cutting units using magnetic cylinders and dies.

Since laser cutting stations are still more expensive to purchase and maintain and are significantly slower and the quality of the die-cut result continues to be variable, there is currently no real alternative to rotary die-cutting. Whether in the printing or die-cutting sector, the industry will continue to benefit from competition between the various systems which is driving technology forward

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