Narrow-web flexo has most recently been defined as any web width less than 20" (508mm). While this is an arbitrary designation, it will serve as a definition for this chapter. The vast majority of narrow-web presses, however, are 16" (406mm) or less, and most are 10" (254mm) or smaller, However, changing market conditions and the need for greater productivity have created a definite trend toward the use of wider presses. Web widths of 10" (254mm) and 13" (330mm) have sup-planted the old standards of 6" (152mm) to 8" (203mm) web widths. Presses width 18" (457mm) to 20" (508mm) web widths are becoming more common.
Narrow-web flexography is also characterized as a rotary process with multiple in-line converting functions. Variable print, or repeat length, capability is a critical feature in the markets served by narrow-web equipment. With alternate printing processes, varying repeat is often accomplished with an intermittent web motion. The elegant simplicity of the flexo ink system, low-cost plate cylinders, and the ease and cost effectiveness of processing plates in a variety of sizes, make an intermittent or platen type of system unnecessary on narrow-web flexo presses. Plate cylinders are easily and economically changed on narrow-web presses, providing the ability to alter the repeat length while maintaining rotary printing. Typical narrow-web flexo presses have a print repeat range from approximately 4" (101mm) to 24" (609mm) in 0.125" (3mm) increments.
It is rare for a narrow-web flexo press to be limited to simply printing. Typical applications will include some form of in-line converting operation, such as die-cutting, slitting or laminating. The ability of narrow-web presses to do multiple operations in-line at high speeds provides tremendous production efficiencies and cost savings to users. The converting operations performed on narrow-web presses are also usually accomplished by rotary meas. However, platen, or flatbed, die-cutting can be used, and foil for stamping can also be fed intermittently.