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.