Piece-Good Printing Issues
Davis examins key issues in piece-good printing, including artwork concerns, aligning cut pieces on press, and maintaining lot-to-lot integrity.
As styles change and consumer demands diversify, so do the types of jobs produced by garment printers. Adapting to changing trends is the only way to remain competitive. One area that continues to grow as printers adapt is cut-piece printing. This month, we will look at some of the production and quality issues involved in printing the individual pieces of a garment before it is assembled. Although cut-piece printing is used for adult garments, it is more common in children's clothing. It allows you to give an all-over printed appearance without the excessive engineering needed to print a very small finished garment. Piece-good printing enables you to image multiple pieces in a single print stroke, particularly useful with toddler and infant clothing. For the press operator, the most noticeable difference between piece-good and finished-garment printing is loading of the fabric onto the platen. But those responsible for engineering the artwork face important differences, too. Artwork considerations Some designs are repeating patterns that may or may not have to match at the seams once the garment is sewn together. Other designs have critical registration requirements, and design elements on each piece of the garment must line up precisely and seamlessly when the pieces are assembled. These are the first considerations to take into account, since the appearance of the finished garment is the customer's primary concern. The artwork must also be engineered to satisfy the job from a production standpoint: It should be designed to allow easy loading of the pieces on the platen. You want to lay out as many pieces of a single garment as possible, making the most of available space on press. Another artwork issue is the number of printed pieces in each garment. On a typical top, you will have a front, back, and sometimes, the sleeves. This gives you four pieces to print at a time. If platen size limits the number of pieces you can print simultaneously, you will have to use multiple passes through the press to print all the parts. Multiple passes are typically necessary when you print matched-garment sets, such as children's shorts and tops. In order for artwork to precisely line up at the seams between garment panels and appear continuous over the seams, you must print the image to the edge of each panel. One approach is to extend the image area beyond the panel edge, which means the graphic will be printed on the fabric as well as the platen. This, of course, leads to problems on press, where ink must continually be cleaned off platens, and in garment assembly, where dried ink in seam areas can gum up sewing needles as the panels are joined. With carefully engineered designs, however, you can avoid these problems. Try to create artwork so that it falls within 1/16 in. of panel edges, not on the platens. The material edges will gather at the seams when the panels are sewn together, hiding the unprinted material and leaving an uninterrupted image. If this still leads to ink gumming the needles during sewing, you can also fade out the image near the edges so that assemblers have a minimal ink deposit to contend with. Piece-good presses The most efficient piece-good printing is done on presses with large platens that accommodate as many pieces as possible. When printing on standard textile presses, some printers use oversized platens. The larger the screens and platens the press supports, the more production you will achieve per stroke. Belt presses are especially well suited for cut-piece printing. A press that uses a belt instead of platens offers far more space for loading fabric. And the inline configuration of belt presses means that machine formats can be extremely large. Belt presses were widely used from the 1960s through the 1980s for decorating yardage, towels, and "all over" printed garments. Although belt printing has declined in popularity since then, the presses are still is use today and produce the majority of cut-piece prints. But whether you print pieces on a belt printer or standard carousel press, the keys to productivity lie in the engineering of the artwork and the associated layout of the pieces on the belt or platen. Registering the fabric on the press Cut pieces are notched in at least two places. These notches serve as guides for lining up the panels when they are sewn together. As a printer, you'll also find these notches valuable because they can aid you in placing panels in the correct locations on the platen. To use these notches, mark the platens in the exact location where each notch on each panel falls when the panels are properly aligned with the image on the screen. Then use these marks to line up each panel during the production run. Some higher-end presses even feature optical registration systems that use lasers to detect panel locations. If the pieces are not properly positioned, the system sends a warning signal to the loader. Lot-to-lot fabric variations The last consideration to address is the lot-to-lot inconsistency that always occurs with fabrics. Keeping fabric lots together throughout production is essential, otherwise pieces may be misgrouped after printing leading to misaligned and misregistered prints around the seams of the finished garments. You risk losing many valuable man-hours and dollars when you disturb lot integrity during cut-piece production runs. When a lot of fabric is cut for sewing, the pieces are grouped into stacks of a given number of pieces. When the pieces arrive for printing, you will have groups (usually 50 pieces per group) of left sleeves, right sleeves, fronts, and backs all individually tied together. Each bundle typically comes with an identification tag stating the lot number of the fabric and the number of pieces in the bundle. By keeping pieces from like lots together at each stage of production, you ensure that the respective pieces can be correctly regrouped when it comes time to sew. Each bundle typically includes a few extra pieces to cover setup and misprints. Garment assemblers face a great enough challenge in maintaining lot integrity from bundle to bundle without the added variable of printing facilities that mix up the goods. Lot numbers must be carefully monitored when pieces are unpacked, printed, and grouped back together for shipping to the sewing facility. The best way to keep lot integrity intact is to keep the identifying tag for each bundle with either the first or last piece of each bundle. Although more labor intensive and time consuming than finished-garment printing, cut-piece production printing can be very profitable. The key is to be aware of the special processing concerns such jobs involve and address them by properly designing your artwork, correctly positioning panels on press, and ensuring that pieces from the same lot are always kept together.