Tips

Narrow webs, under 30" wide, contend with the same wrinkling challenges as wide web applications. Wrinkles cause product defects, which lead to lost profits. Whether you print, die cut, coat, laminate, slit or otherwise convert your narrow web, you may face some unique challenges to removing web wrinkles.

Many narrow web applications are limited in space in the machine direction. Placing an anti-wrinkle system in your narrow application may be difficult just from the point of finding a spot in the machine for it to be placed. Swapping out rollers may be difficult and anti-wrinkle rollers require some web path geometry guidelines to be effective. Depending on the anti-wrinkle device, unsupported web lead-in and lead-out distances may be important as well as wrap angle.

Adding to the placement complications; it is important to keep in mind a few rules of thumb when it comes to effectively removing web wrinkles for your application:

• Any anti-wrinkle system you choose can only remove web wrinkles that enter the system. This means anti-wrinkle systems cannot affect wrinkles, post anti-wrinkle system placement.
• Anti-wrinkle systems DO NOT change your web. If your web has inherent defects that are causing it to wrinkle, wrinkles may return. Anti-wrinkle systems remove wrinkles prior to an operation. Normally, before wrinkles become creases, which brings me to my next point.
• Nothing removes a crease. Anti-wrinkle systems prevent creases by removing web wrinkles before they become creases. Prior to a nip station or printing station or rewind station as a few examples.

What this all means to you is the closer the anti-wrinkle system is to the problem area, the better. However, your application may not allow the placement of certain types of anti-wrinkle systems where they are most required.

Typically, bowed rollers require a long unsupported web distances leading into the bowed roller and a short unsupported web distance leading out of the bowed roller. Wrap angles should be less than 30 degrees. In fact, most of the time, when bowed rollers aren't solving your wrinkle problem or they are causing more problems than solving, it's due to much wrap angle around the bowed roller. Due to the geometry concerns, bowed rollers may not be the right fit for a lot of narrow web applications. In addition, bowed rollers can require higher tension levels than your application provides. If this is the case the bowed roller must be driven, externally (not by the web) further complicating locating a proper place to mount the bowed roller.

Nip type antiwrinkle systems are extremely aggressive and are very effective at removing wrinkles from webs under even the most demanding applications. However, this anti-wrinkle system also (like bowed rollers) works best with long unsupported web distance leading into them. They must be mounted on each edge of the web, so often, narrow web converting machine side frames will not accommodate the space they require. Bottom line, this is a great anti-wrinkle system to utilize if you can fit it into your machine but there in lies the issue. Fitting into your narrow web converting process may not be possible.

Expanding surface anti-wrinkle rollers may be your best option. These rollers are very aggressive and adjustable. They include a linear (no bow), smooth (no grooves) surface that expands for 180 degrees of rotation and contracts for 180 degrees of rotation. Your web enters the roller where the surface is contracted and exits on the expanded side. This roller removes wrinkles with a stretching surface under your web. Almost all the anti-wrinkle action takes place on the roller face so unsupported web lead in and lead out distance is not a concern. This anti-wrinkle system is perfect for light tension applications as it requires low amount of torque to rotate and rarely requires an external drive system. Expanding surface rollers are easy to mount, they typically, simply, replace an existing idler roller. This roller is easiest to locate in your narrow web converting machine closest to the area where wrinkles are causing the most problems.

Choosing the right anti-wrinkle system for your narrow web converting application will reduce or prevent defects in your product, increasing your profit and providing fast ROI.