Photopolymer Plates & In-the-Round Sleeves Can Work Together

As printers seek ways to produce quality output while minimizing downtime, waste and cost, they are faced with a bit of a quandary.

When two different printing technologies can produce comparable quality output, but cost and press life is significantly less for one than it is for the other, which is best? Using both may be the ideal answer. It’s often a hybrid solution worth exploring.

Every flexographic print operation is different. There’s no one best application that’s perfect for all. When considering photopolymer (PP) plates vs. in-the-round (ITR) laser-engraved print technology, there are pros and cons to each. In some cases, however, those differences present a cost-efficient use of both.

A hybrid solution—where both PP and ITR are employed—depends on the fit each application offers each specific flexographic operation.

The Photopolymer Fit

Photopolymer plate technology has been around for a long time. Most flexographic printers purchase photopolymer plates from third-party providers, while larger printers may produce their plates in house—requiring a significant investment in equipment. In either case, the initial acquisition cost is a factor of the many steps in producing a PP plate—including liquid castings, multiple exposures, washes and drying.

Still, photopolymer plates are significantly less expensive than laser-engraved sleeves and rollers—making then highly cost effective for short runs. The actual cost of PP plate ownership, however, comes from a set of different factors, including lifecycle. For example:

• Plates require skilled labor and the time to mount accurately
• A mounting tape film needs to be applied to hold the plate on the press mandrel
• Operators must manually target placement using camera imaging
• Plates are often glued along the edges
• Rider strips are added along each side of the plate

Other PP plate factors include:

• The consistent height and vertical profile of PP plates allow for excellent production of thin line art, such as UPC codes
• PP plates are available for printing on a wide range of substrates and with a variety of inks
• PP plates have a far shorter press life than ITR laser-engraved sleeves/rollers
• Any air bubbles under a mounted plate can cause it to separate from the mandrel
• Plates can lift off the mounting surface at high speeds
• Even with current image-modifying software, there can still be print distortion caused by bending a flat engraving over a round press cylinder
• The seam between plates, while very narrow, will create a “ghost line” where there is no ink laydown
• The gap between plates can cause unwanted “bounce,” forcing reduced press speeds

  

ITR Fit

Laser-engraving ITR technology has continued to make huge advances with machine performance as well as operating software. The process still uses lasers to “carve” dots and patterns on an elastomer (rubber) surface, but with greater precision than ever. Elastomer compounds have also evolved to provide better response to laser engraving while also being formulated for specific inks, required hardness and durability.

There are many considerations when looking at ITR laser-engraved technology, such as:

• ITR elastomers are applied to composite cylinders (sleeves) or to steel mandrels (rollers)
• The newest laser-engraving systems can cut screens up to 150 lpi
• ITR print sleeves and rollers are highly durable—making them ideal for longer pressruns
• Fine-particle polymers can be precision carved to produce sharp, thin lines—ideal for imprinting small UPC bars
• ITR sleeves are easily installed and removed—simply sliding on or off an air-actuated mandrel
• ITR sleeves and rollers can be produced to exacting diameters through precision elastomer laydown and finishing—to fit any existing press mandrel
• ITR elastomer compounds can be formulated to effectively apply inks designed for PP plate applications—no need for inventories of different ink types
• ITR sleeves can be produced up to 125-in. in length