What Occurs Inside a Zero-Speed Splicer When a Coldset Web Press Changes the Expiring Roll?

At the unwind stand of a coldset web offset press, the zero-speed paster is the dominant splice point where a repulpable forms-splicing tape must perform without disrupting the folder. A typical press line consists of multiple reelstands, a web accumulator, printing units, a former folder, and a delivery stacker. The expiring reel is braked to a stop while the new reel is pre-accelerated to line speed by the paster wheel. The splice is made by pressing the tape-bearing leading edge of the new reel into the expiring web at the paster nip. In this downstream operation, the application ratio is not a weight-percent formulation loading but a splice incidence rate: one continuous machine-direction tape strip per reel change, applied across the full web width with a 10–15 mm edge setback. For a web width of 1,400 mm using a 25 mm strip, the tape area consumed per splice is approximately 0.034 m². The edge setback is critical because adhesive squeeze-out beyond the web edge will contaminate idler rollers and can transfer to the former board. The splice must exhibit sufficient fiber-tear adhesion to survive web tensions in the range of 200–600 N/m, with parent-sheet tensile behavior measured according to ISO 1924-2. The zero-speed paster is the relevant equipment class: the new reel is pre-accelerated, the festoon is filled, and the paster jaw closes against the expiring web. If the tape lacks adequate tack at the paster nip, the splice breaks before the festoon reaches the required storage length. If the tape is too aggressive, adhesive transfer to the new reel surface during pre-acceleration can cause blocking and subsequent web breaks. The terminal product types in this segment are newspapers, advertising supplements, retail inserts, and coldset-produced catalogues. Compliance for this sector is process-based: the printing works must maintain incoming paper and consumables under an environmental management system such as ISO 14001, and EU market supply requires compliance under REACH Regulation (EC) No 1907/2006. For printed matter intended for direct or indirect food-contact use, such as direct mail coupons inserted into food packaging, the converter must separately verify the splice tape component under 21 CFR 176.170 for aqueous and fatty food contact or under EU Regulation (EC) No 1935/2004 when an EU food-contact declaration is made.

Inside the dry-end reel and sheeter deck, parent rolls are transferred from the winder to a synchro-fly sheeter, where the web is slit, cut into folio sheets, jogged, and palletized. The splice at the sheeter unwind is made to replace an expiring parent roll without rethreading the entire line. 3M 910 is used as the lap-splice tape because the adhesive and backing are designed to disperse in the mill's broke system. In this segment the usage rate is one full-width strip per parent roll change; the strip length equals the web width minus two edge setbacks. For a typical fine paper web width of 1,650 mm and a 19 mm tape width with 10 mm edge setbacks, the tape area per splice is approximately 0.031 m². The addition ratio is therefore not a formulation addition in the bulk papermaking furnish but a low-area splice incidence. The production process includes decurling, slitting, cut-to-register, and layboy stacking; a splice that is too thick will create a stacker jam at the layboy because the cut-sheet stack height changes locally. Process compliance is governed by mill product standards: fine paper intended for food service or direct food contact must be evaluated under 21 CFR 176.170 for paper and paperboard components, and EU food-contact declarations require Regulation (EC) No 1935/2004. Repulpability of the splice in mill broke is demonstrated by TAPPI UM 213, with the dispersible adhesive showing no unrepulped adhesive mass at the screens under the mill's stated pulping conditions. The operational boundary is that the tape bond should be allowed to develop before the web reaches the draw rolls; on high-speed sheeters running above 350 m/min, a splice made immediately before the draw nip may slip. Terminal product types are cut-size office paper, folio sheets for commercial printing, and paperboard sheeting for packaging. The absence of visible adhesive residue in broke is a critical quality parameter because residual adhesive can form stickies in the mill's recycled furnish and reduce sheet formation quality.

Tissue Converting Unwind Splice Caliper Control and Pulper Dispersion Limits

Tissue rewinding and log saw operations convert parent rolls into consumer-sized finished rolls at line speeds that routinely exceed 600 m/min. The unwind splice must disappear in the finished log; any local caliper increase becomes a hard band, which produces log saw blade deflection marks and wrapper tears. The tape used is 3M 910 in a single continuous strip at 19 mm width for most 15–45 g/m² tissue grades. The edge setback is held at 10 mm from the web edge, and the strip spans the full web width; for parent rolls above 2.7 m width, two 19 mm strips separated by a 200 mm un-spliced gap may be used only when the splice design is verified on the specific rewind stand. The consumption rate is one strip per parent roll change, and the tape area is therefore a function of reel width. The production process includes unwind, embossing, perforating, rewinding, log sawing, and packaging. At the rewinder, the splice passes through an embosser nip where a thickness difference of 0.08–0.10 mm caused by the tape backing is significant because the base sheet thickness may be only 0.04–0.10 mm per ply. Caliper verification is performed by ISO 12625-3 for tissue thickness. If the splice exceeds the permitted caliper window, the embosser may cut the sheet at the edge of the tape band. The processing boundary is therefore set by the rewinder's nip gap, not by the tape's tensile properties. In broke repulping, the adhesive must disperse under neutral-to-alkaline pulper conditions at temperatures of 40–60°C; repulpability is checked by TAPPI UM 213. For products that may be marketed for food-contact wiping applications, EU Regulation (EC) No 1935/2004 applies, and US converters should verify 21 CFR 176.170 if the tissue is declared for contact with aqueous or fatty food. The terminal product types are bathroom tissue, kitchen paper, and napkins. The primary failure mode observed on production lines is not splice break but caliper-derived hard band formation; this distinction governs all converting parameters.

On the singlefacer wet end, medium is pulled from an unwind stand through preheating drums and then into the flute-forming nip. Liner webs are spliced at both the singlefacer and the double backer. 3M 910 is placed across the full width of the expiring medium or liner as a single lap splice, with 12–15 mm edge setbacks to avoid web guide interference. A 25 mm tape width is common for medium grades up to 160 g/m²; for heavier linerboard above 200 g/m², a 50 mm width may be used after conversion validation. The consumption rate is one splice strip per unwind roll change, which means the tape area per splice equals the web width minus edge setbacks multiplied by the selected tape width. This is not a formulation loading in the adhesive sense but a downstream joining frequency. The corrugator runs at speeds between 150 m/min and 300 m/min, and the splice must survive the preheater and hot plate zones. If the preheater surface temperature exceeds 180°C, published data for this specific configuration is limited; the converter must run a trial because the repulpable backing may embrittle. Compliance for corrugated shipping containers that are intended for direct food contact falls under 21 CFR 176.170; secondary packaging without direct food contact does not automatically require the same clearance, but EU market declarations for food packaging are still assessed under Regulation (EC) No 1935/2004. Repulpability of splice waste is evaluated by TAPPI UM 213; residual adhesive particles in the corrugator broke can decrease ring crush and edge crush values in the finished board, so the mill screens are monitored for visible stickies. The downstream process includes singlefacer fluting, starch adhesive application, double backer heating, slitting-scoring, and die-cutting. Terminal product types are regular slotted containers, die-cut trays, and e-commerce shipping boxes. The operational limitation is that the splice must be located away from starch glue lines because adhesive mass under the glue line can change the glue uptake and cause a dry bond.

When Continuous Forms Presses Run Carbonless or Pressure-Seal Stocks, Splice Flagging Must Not Transfer to the Tractor Pin Band

Continuous forms presses differ from publication web presses in that the web is narrow, pin-fed, and frequently composed of multiple plies. The unwind splice on these presses is made with 3M 910 specifically because the tape is repulpable in the forms plant's broke and does not introduce a filmic backing that would interfere with line holes. The application ratio is one continuous machine-direction strip of 19 mm tape per splice, applied across the full width of the narrow web and cut to avoid the punched line-hole margin. The tape edge is set 3–6 mm away from the pin band so that tractor pins cannot perforate the adhesive and carry it into the pressing station. For a 300 mm wide form web, this placement creates a tape length of approximately 288–294 mm per splice. The production process includes unwinding, lithographic or flexographic printing, numbering, perforating, cross-perforating, gluing, folding, and reeling or fanfolding. The splice must survive not only the press tension but also the mechanical punching of the pin-feed sprockets; a splice that flags will catch on the fold rollers and tear the web. Compliance is governed by the end-use application: forms used as pharmaceutical leaflets may require component review under 21 CFR 176.170 if they are inserted into primary packaging and direct product contact is possible; otherwise, the primary technical compliance method for the splice is TAPPI UM 213. The terminal product types are continuous business forms, pressure-seal mailers, cut-sheet laser forms, and multi-part carbonless sets. The operational boundary is that the adhesive must not be positioned under a magnetic numbering printer or an inkjet head, because adhesive bleed can contaminate the print nozzles and generate variable-data print defects. Published data for this specific configuration is limited when the forms press uses heavy carbonless front-back coatings above 120 g/m²; validation trials are required before the splice is placed in regular production.

Envelope and bag converting lines draw the web from a reelstand, print it in one or two stations, and then cut or fold the blank in register. The splice at the reelstand unwind is made with 3M 910 as a full-width strip, with 10–15 mm edge setbacks to keep adhesive out of the folding plough and window patch applicator. On paper bag machines running basis weights above 90 g/m², a 25 mm tape width is preferred; on envelope lines running lower basis weights, a 19 mm width is sufficient. The consumption rate is one splice strip per parent roll change, and the tape length equals the web width minus the edge setbacks. In the production process, the web moves from the reelstand through a flexographic or lithographic print tower, then into the envelope folding cylinder or bag-forming line. The splice must not leave adhesive on the folding cylinder because this will cause sequential blanks to stick and fold out of register. Compliance for paper sacks and grocery bags that may contact dry food is evaluated under 21 CFR 176.170; EU food-contact declarations are assessed under Regulation (EC) No 1935/2004. Repulpability is verified by TAPPI UM 213 for converter waste. The terminal product types are envelopes, paper mailers, carrier bags, and paper sacks. The main processing limitation is that the splice should not be placed directly over a printed area where ink coverage exceeds 250% total area coverage, because the adhesive can soften the wet ink and create offset onto the following web.