For many products, center winding is better for winding multiple rolls on a common shaft, especially with differential winding bars. Center winders have more automatic cut and transfer options. Surface winding often can wind at lower tensions than center winding and exerts less torque on the building roll (avoiding torque-related cinching). As mentioned above, surface winding is good for rolls with large build-up ratios. Q: Which is better - surface or center winding?Ī: It's not about which is better. You could never do a “rip and tuck” with films or foils without a lot of waste from wrinkles and impressions, so center winding and automated (or stopped) transfers are preferred. If there is a core start wrinkle, the soft paper layers quickly mask them. Second, many paper winders use a simple “rip and tuck” roll transfer. Surface winding takes roll diameter out of the torque range requirements. If tensioning torque is generated from the roll's center - the definition of center winding - the torque required (tension × radius) will have a torque range impossible for most motors. First, paper roll properties allow winding to extremely large-diameter build-up ratios, where the final roll's diameter may be 20x the core diameter. In the paper industry, you will see more surface winding for two reasons. This dominance is not because it is the best winding method, but because it is simpler to build and easier to automate roll transfers. Q: Which is most common - surface or center winding?Ī: If you survey winding equipment shown at the CMM show, center winding dominates the converting industry. Adding a winding nip to a center winder improves roll quality. A two-drum winder has two winding nips that cradle the winding roll (and often a third winding nip on top of the roll). Pope reel winders have one large central drum that contacts the winding roll. You can't have a surface winding without a winding nip roller (a.k.a. Q: Are winding nip rollers used in both surface and center winding?Ī: Yes, winding nip rollers are used in both. Some of the same roll quality benefits also are found using a close cousin of the winding nip - the gap roller. The winding nip has many aliases, including lay-on roller, pack roller, surface roller, and contact roller.

The winding nip is a roller, driven or idling, that remains in contact with the winding roll throughout its buildup. One key to quality wound rolls is the winding nip.

It seems easy enough, but done poorly, winding can turn 100% good product into waste very quickly. At the checkout line, the checkout assistant opens a bag, drops in your bread, then your eggs, then the gallon of milk - splat.

Winding - the final step in many web converting processes - is like bagging groceries. It's not obvious how winding adds value to your product (it does), but it is obvious when it's done poorly.

Roller splat level pick