Revved Up to Retrofit
November 2003
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Narrow-web label converters looking to expand into flexible packaging may want to consider press retrofitting as a first step—but there are tradeoffs.
Imagine this: your first car is a '92 Ford Mustang, two-door with an obnoxious red interior. While it met your initial driving needs, you are ready for something better—a little extra power, a CD player, and maybe a sun roof. While right now purchasing a new car would be a real stretch, you know you can get some, but not all, of what you want by upgrading what you have.
Converters running narrow-web presses designed for pressure-sensitive labels are facing a similar situation when looking to drive on the flexible packaging highway. Their standard presses are great for heavier paper stocks, but flexible packaging brings with it the need to run thinner film substrates. While purchasing a new press may be too large and risky of an investment at this point, retrofitting a press is an option to consider.
Press retrofitting, though, must be carefully thought out and approached in terms of the problems that need to be addressed, and in your expectations. Terry Trexler, product manager for Gallus (Philadelphia, Pa.), lists the primary issues that must be tackled as web tension, heat management, static build-up, and ink adhesion. Each of these must be addressed to a degree determined by the individual application.
Addressing retrofit issues
Web tension control is one of the main issues to be tackled when retrofitting, and it needs to be addressed in several areas of the press. Pat Bowdy, engineering manager at Ko-Pack (Williston, Vt.), says the underlying requirement for precise tension control of films is because of the instability they exhibit when tension is applied.
Gary Teeter, retrofit applications engineer at Mark Andy (St. Louis, Mo.), points out the sensitivity of running films on a standard label press. "Infeed pacing is critical to web tension and management of the thinner unsupported substrates," he says. "Standard label systems typically cannot be set low enough, which results in too much web tension."
Teeter also points out the importance of using low inertia idler rolls. These help reduce strain added to the film as it travels through the press.
Another important area for tension control, according to Teeter, is to have a separate drive on the plate rolls versus the impression rolls. This prevents web tension changes when making a register change at any station.
Imagine this: your first car is a '92 Ford Mustang, two-door with an obnoxious red interior. While it met your initial driving needs, you are ready for something better—a little extra power, a CD player, and maybe a sun roof. While right now purchasing a new car would be a real stretch, you know you can get some, but not all, of what you want by upgrading what you have.
Converters running narrow-web presses designed for pressure-sensitive labels are facing a similar situation when looking to drive on the flexible packaging highway. Their standard presses are great for heavier paper stocks, but flexible packaging brings with it the need to run thinner film substrates. While purchasing a new press may be too large and risky of an investment at this point, retrofitting a press is an option to consider.
Press retrofitting, though, must be carefully thought out and approached in terms of the problems that need to be addressed, and in your expectations. Terry Trexler, product manager for Gallus (Philadelphia, Pa.), lists the primary issues that must be tackled as web tension, heat management, static build-up, and ink adhesion. Each of these must be addressed to a degree determined by the individual application.
Addressing retrofit issues
Web tension control is one of the main issues to be tackled when retrofitting, and it needs to be addressed in several areas of the press. Pat Bowdy, engineering manager at Ko-Pack (Williston, Vt.), says the underlying requirement for precise tension control of films is because of the instability they exhibit when tension is applied.
Gary Teeter, retrofit applications engineer at Mark Andy (St. Louis, Mo.), points out the sensitivity of running films on a standard label press. "Infeed pacing is critical to web tension and management of the thinner unsupported substrates," he says. "Standard label systems typically cannot be set low enough, which results in too much web tension."
Teeter also points out the importance of using low inertia idler rolls. These help reduce strain added to the film as it travels through the press.
Another important area for tension control, according to Teeter, is to have a separate drive on the plate rolls versus the impression rolls. This prevents web tension changes when making a register change at any station.
Companies Mentioned:
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