Getting the Right Impression

By Kevin Carey, Diecutting Information Exchange

Traditionally, ingenuity and individual invention led to product and service development, the creation of commercial opportunity, and an evolutionary change in consumer taste. As Thomas Edison observed: "No one asked me to invent the light bulb. "However, in a highly competitive global marketplace, in which consumers dictate volatile, short lived trends and demand faster and faster new product development, rapid technological innovation is essential to survival. In the diemaking and the diecutting industry the scope of change and the pace of transformation from old to new technology is accelerating.

Fortunately, the diecutting process, although subject to progressive automation, is still converting sheet and web materials using principles and practices which have been in place, almost unchanged for more than 100 years. Although perhaps not for much longer....?

Soft or Hard Anvil Diecutting?

One of the fundamental principles of diecutting, common to every technological option, is a requirement to keep the cutting tool and/or the knife edges as sharp as possible for as long as possible. The solution to knife edge protection evolved into two approaches to diecutting. These are cutting "Into" or cutting "Onto".

In soft anvil diecutting the anvil is a softer material than the cutting knife edge and inevitably this sacrificial surface suffers progressive damage as the production run continues. However, the knife edge is preserved in optimal cutting condition and the cost of replacing the aluminum, plastic, or rubber anvil is less than the benefit derived from consistent output quality and performance. However, even this potential Achilles heel is minimized by the use of laterally oscillating the soft anvil in rotary diecutting and in using a low cost moving paperboard belt in revolutionary presses such as the Ttarp System from Buffalo, New York.

In hard anvil or steel-to-steel diecutting, knife edge damage is minimized in several ways. The obvious first step is to improve the design and fabrication of the platen press, to improve the precision of machined parts and assembly tolerances, and to reduce the overall size of the cutting surface to minimize variability. In this method the platen is set to the height of the knife plus a "gap" and variation is adjusted by adding compensation shims to the underside of individual knives.

One of the most innovative approaches to protected cutting edge integrity is accomplished by using a knife made with compressible "feet" or protrusions on the base of the steel, which act like shock absorbers to accommodate variation in the platen stack, the cutting plate, and in the steel rule die. These "self-leveling" knives have never achieved the degree of success they have Internationally in the United States because of resistance to change and a failure to make simple changes to the method of tool manufacturing.

Another innovative and highly successful method of preserving edge sharpness and in reducing set-up is the insertion of an "Elastomer" or a layer of compressible material into the platen stack. These materials can be placed behind the cutting die or under the cutting anvil. Their role is to act as a leveling device to absorb the inevitable variation in the die and cutting anvil flatness, and to compensate for uneven platen mechanism wear. Pioneers amongst this group are X-Print, the Wilson Tyler Group, and Carton Craft Die Supply. As with other methods of press leveling these techniques require simple but key changes to the mostly ineffective make-ready methods currently in use.

The most noted change is the integration of several disciplines to gain the benefit of both cutting onto and in cutting into. This technique refers to the use of a steel cutting plate of a lower Rockwell hardness than the edge hardness of the knife. In response to any variability in cutting performance the die is cycled lower and some of the knives will slightly penetrate the sacrificial steel cutting plate. However as the cutting plate is softer than the knife the sharpness of the edge is protected and using a more precise overall pressure adjustment, cutting plate damage is minimized. This combination of a steel to steel cutting system with the benefit of a softer "sacrificial" anvil is highly successful and is gaining broad acceptance. Not only does this system of diecutting ensure consistent output quality it significantly reduces the time require to level or to make-ready the press. As you would expect Bobst in the platen field and several manufacturers in the rotary arena are important players in these developments.

These innovations are important but they do not address a fundamental question of diecutting? Platen or Rotary Technology?

Platen or Rotary Diecutting?

The earliest history in the printing process describes the adaptation of a wine press into a crude "press" where "paper" was compressed against an inked, hand carved relief tablet. From the beginning the printing process and subsequently the diecutting process were dominated by various forms of stamping mechanisms where the material being printed was sandwiched between a level tool and a flat Platine. In this application volume was less critical as a limited market was more interested in matching the quality of the hand scribed predecessor to the printed book.

Naturally the new information medium rapidly exploded through Europe and the race for innovation in high volume manufacturing had begun. Fueled by an industrial revolution introducing new materials, new methods of machining, and new power sources, thirst for books, pamphlets, and newspapers drive entrepreneurial development at an accelerating pace. The natural limitation of the hand fed sheet press led to the development of a hybrid machine, the Cylinder Press.

The cylinder press combined the potential of an efficient rotary system with the simplicity and the existing system of fabrication for flat, typeface materials or formes. In turn the development of alternative print technologies and flexible tool manufacturing gave birth to the rotary press where both impressional surface were curved and the material could be printed in a sheet or in a continuous web. Then as now the primary question facing the industry professional investing in the future became platen or rotary and sheet or web processing?

Rotary diecutting options include a wood shell which is processed similarly to the flat steel rule dieboard, a flexible clamped or thin magnetic wrap around tool which is etched, and solid steel tools, utilizing either rotary pressure cut or rotary crush cut technology, which are machined in segments or sections and assembled upon a cylindrical core.

The rotary soft anvil or steel to steel diecutting system utilizing a wooden hand jigged or laser cut plywood shell is experiencing a rebirth as the combination of more precise toolmaking precision, combined with a sacrificial composition or a "soft" steel cutting plate, to provide the option of a true male and female system of diecutting, are aiming at reasserting themselves in the thinner fluted/laminate market currently dominated by platen diecutting.

The success of the flexible plate cutting systems in the label industry, where the traditional paper materials evolved into diecutting increasingly more complex and difficult to convert plastic substrates, generating expansion and new market opportunity, has led to an increasing penetration of this technology into the folding carton market. The leaders in this field of innovation are predicting further consolidation of the label industry to rotary diecutting, and a more gradual penetration of this technology into higher volume folding carton applications, where the investment in modular systems of toolmaking is commercially viable. For more information about the power of these "flexible" systems of manufacturing Atlas and Xynatech are obviously both the pioneers and the technical leaders in this field.

Naturally, to control unit cost and to meet the scale of product output required in high volume folding carton applications manufacturers inevitably gravitate toward the most efficient technology available. In this field of rotary diecutting the use of Rotary Pressure Cut and Rotary Crush Cut technology, where tools are made from machined sections and components, are the dominant system of converting. The technical advantage of separating creasing and cutting into a sequential alignment of upper and lower machined cylinders is the most efficient method of delivering a printed, precise, and fully separated, folding carton, at high output speed. The barriers to entry in this system of manufacturing are the high cost of tool design and fabrication, the lead time required for toolmaking, and the investment in several modular press units into which the tools must be installed. Although there are a limited number of toolmakers in this field, Bernal Rotary Systems, is a world leader in this technology.

Web fed platen and sheet fed platen diecutting systems have hardly been idle during this period of rotary development. new mechanical systems, coupled to advances into stiffer, lighter fabrication, and a logical reduction in the overall platen cutting area of the press are generating higher sustained production speeds with enhanced registration control and lower set-up waste. With their primary advantage being the relatively low cost of tooling, the inherent design flexibility, the widespread availability, and the fast turnaround of new tools, these systems of manufacturing are adapting to both an established high volume customer and to an increasingly short run, Just-In-Time, price-sensitive marketplace.

Open to change

Where is the future of diecutting? Clearly a global perspective would show a trend toward a significantly smaller sheet size; to simpler and faster set-up technology; to progressive computer-integrated-automation; to an intense focus on pre-press and off press preparatory systems; to an integration of soft and hard anvil techniques; to press and tool "calibration" disciplines; and to a logical progression toward more effective and more efficient rotary systems of diecutting manufacturing.

Naturally, every supporter of every technological alternative can and will take issue with this assessment as every perspective is inevitably influenced by personal technical experience and by the view from a specific geographic location. The three main financial world markets are all pursuing trends conditioned by their own environment and the different demands of each complex consumer market.

However, in this region it is vital we abandon our emotional hold on converting the largest sheet size possible, it is essential to implement a concentrated focus on the poorly understood principle of off-press make-ready; it is vital to transform from an individually based manning system to a team assault on productive performance; and it is important to lower our resistance to fundamental change and to test each of the new techniques, materials, and technologies without prejudice.