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FLEXO Magazine : October 2011
To understand the strengths and weaknesses of splices during production, it is important to understand the splicing process. SPLICING’S SPECIFICS There are currently two ways to splice roll stock; manual static splicing and automatic flying splicing. Manual static splicing takes place when the web is completely stopped, at which time the expiring web is attached to the new web, and the web feed is resumed. Certain splicing equipment can allow a press to continue operating during a manual static splice through festoons that accumulate the web and feed the press while the expiring web is spliced to the new web. On certain older presses, the press is stopped entirely, and the old web is affixed to the new roll. While splices performed this way are mostly successful, the press efficiency is dramati- cally decreased due to the slow or stopped press. Conversely, automatic roll-to-roll flying splice systems allow for continuous operation of the press without stopping or even slowing the press down to change rolls. Most wide- web flexographic presses have a turret system that has one roll unwinding and another full roll ready when the produc- tion roll runs out. When the expiring roll is nearly depleted, the new roll is automatically positioned close to the expiring roll, brought up to a matching speed, then simultaneously attached and cut from the expiring web, while the press con- tinues to operate. In order to be successful, the flying splice process requires that the new web be equipped with an adhesive system to adhere the expiring web, as well as a harboring mechanism for the new web to separate from the expiring web, and to en- sure that the leading edge of the new web is secured as it is brought up to a matching speed of the expiring roll. While this appears to be a relatively simple concept, the process can be complicated for the following reasons: • The adhesive system must stick to a variety of substrates including film, foil, polyethylene (PE), polypropylene (PP), cellophane, and polyester (PET). • Tear-away tabs must hold the leading edge down on all above-mentioned materials. • Tear-away tabs must not prematurely break before the splice is made, yet break easily when the web is changed. • Adhesive must not stick to any cylinder as the splice goes through the press. • The adhesive must have sufficient sheer strength to with- stand press tensions. In addition to the above critical factors, the splice must be successful at the accelerated print speed. If a press that can successfully print at 800 mpm must decrease the running speed by half or more every time a roll is changed, it be- comes apparent that time and money are being wasted by the splicing process. When considering all the factors and the possible error points, it’s easy to understand the critical nature of the splicing process. PROCESS IMPROVEMENT To maximize speed, decrease down time, and avoid splice breaks that can obliterate all high-tech efficiencies, it is vital to have a simple and easily repeatable standard operating procedure (SOP) in place to ensure all splices are prepared properly. An ideal SOP should contain the following elements: • A splice pattern that is simple and repeatable by all operators. • A pattern that works on all presses. • Adhesive that sticks to all substrates and does not prema- turely release at top speeds. • An adhesive system that resists shear forces (or resists being pulled apart) by the tension in the press. • A system that secures leading edges of new rolls onto expiring rolls. • Materials that do not require liquid glues, as they are sticky and will quickly grab a moving web • Measureable splicing efficiency (tesa tape, inc. offers a fast and easy splice calculator to help determine splice efficiency.) If you track your splicing successes, or fail- ures, it’s easy to determine whether or not this is an area that is costing valuable time and money. BEST BET The one splicing method that offers the best solution for overcoming all of the above challenges is the straight-line adhesive splicing tape. Straight-line splicing tapes feature an all-in-one design that combines a contact adhesive designed to adhere to various substrates, while also incorporating a break-away leading edge that eliminates the need for tear- away tabs altogether. Furthermore, straight-line splicing tapes are inherently designed with only one application SOP. It can only be ap- plied by one method, ensuring consistency by all operators. This means there is a consistent, measureable, and auditable splicing design used throughout the entire plant. Because the web speed is constant, the web tension remains constant, thereby producing consistent results, while also reducing the amount of waste in downstream processes. n About the Author: Joe Prunier is market manager, print and web processing for tesa tape, inc. tesa tape offers a straight- line splicing tape specifically designed for splicing filmic and foil substrates. tesa EasySplice® FilmLine Plus. The firm’s industry-leading adhesive has been tested on a variety of highly critical surfaces at web speeds of up to 800 mpm without reducing press speed. tesa print and web processing specialists have a splice efficiency calculator to help measure process efficiencies. For more information on flying splice technology or the tesa EasySplice® FilmLine Plus products, contact firstname.lastname@example.org. 30 FLEXO october 2011 www.flexography.org © tesa tape, inc. • 1-800-426-2181 • www.tesatape.com ISO 9001:2000 Certified • ISO/TS 16949:2009 Certified • ISO 14001:2004 Certified ® Introducing Speed and Efficiency for Your Print Crew NEW tesa Softprint® FE Plate Mounting Tapes tesa EasySplice® FilmLine PLUS Splicing Tape • Plate Mounting • Roller Wrapping • Splicing • Core Starting • Edge Sealing • End Tabbing • What Every Pit Crew Needs n Fast mounting n Splice at high speeds n Easy de-mounting n Improved adhesion n Superior print quality n Increased throughput For high-speed results, call 704-553-4698 NEW What Every Pit Crew Needs What Every Pit Crew Needs tesaFLEXO8x10.875PrintAdREV.indd 1 8/2/11 2:22 PM