Workflow demystified: From start to finish.
By Vince Cahill
Like other manufacturers, printers of textiles want to see jobs moving smoothly and quickly in a steady stream through their facilities, with only interruptions for scheduled preventive maintenance. When an operation can efficiently move materials and inventory in and out the door with error-free production, timely billing, and good customer service, shop owners can imagine the wealth and security that this well-oiled operation is making for them.
Good luck and fortuitously “being in the right place at the right time” can account for a fair amount of these achievements. However, most successful operations start with a vision that becomes a plan and design that considers relevant history, current resources, prospects, and opportunities. How do you flow orders through your print shop to produce high-quality printing efficiently? You might decide to take a nap and figure it out in your dreams or you could continue reading to discover some suggestions and ideas for subsequent dreams and musings.
Working your workflow
Workflow includes virtually all aspects of your business: planning, financing, accounting, legal requirements and obligations, hiring and training, developing products and services, acquisitions, marketing, sales, receiving and processing orders, purchasing, managing inventory, quality control, shipping, evaluating organizational progress, and distributing rewards to the business stakeholders.
While an encompassing overview of these areas can help integrate all aspects of a business, the task of painting such a grand panorama will often prove daunting. Breaking down the workflow structure into manageable components and designing the efficiencies and compatibilities for each of these, and then integrating each into a smoothly functioning business, often yields profitable results.
For the purposes of this article, workflow does not include computer software workflow controls for managing the print manufacturing process, but is focused on designing the character of physical space and accommodations of a digital print shop to achieve maximum efficiency. Software can then help with the business management, accounting for and directing jobs through a well-organized space.
Designing the workflow system involves organizing both physical and virtual space and time, with a recognition of inevitable changes in workflow design. Two-dimensional maps, three-dimensional models, and four-dimensional timelines and charts can help you visualize and organize the flow of work through your shop.
Keep it clean
Digital textile printing requires some minimum space conditions. Rolls of textile materials have weight, shape, and dimensions. Dust, grease, oil, and some chemicals can interfere with printed ink sticking to or dyeing textiles. Printers must protect their textile media from contamination during handling and storage.
One of the first requirements in planning the workflow of a textile digital printing operation is cleanliness. Textile media complicate the issue because most fabrics produce lint and offer a large, often absorbent, surface area for the capture and retention of contaminants. Digital textile printers often will wear clean gloves to prevent the transfer of their hand oils to their media. Such oils can interfere with inkjet ink attaching to areas where body oils have transferred. Because screen-printing deposits an excess of ink, it can often overwhelm the light oil deposits from barehanded touching of print fabric. Inkjet printing, on the other hand, deposits just enough ink to color the surface without much excess or ability to overcome unprotected handling.
Supporting fabric from the interior of the roll core instead of resting fabric on a shelf or other flat surface, or crushing the fabric core particularly toward the width-bolt ends can distort the print. Stacking heavy bolts one atop another can also damage fabric and adversely affect print quality.
Some printers store their print fabrics vertically while others support them on rigid bars through roll cores. In either case, you should keep rolls off shop floors, as walking on them deposits dirt unless working in a clean room. Particulate dirt, dust, and lint will eventually settle out of suspension on surfaces that are below them, particularly floors for most locations.
The operation of textile printing equipment requires sufficient space to perform all of the functions that the process requires. It needs space to load and unload the maximum roll widths, diameters, and weights. Printers should not attempt to lift more than half their weight by themselves if in good physical condition. Generally, it is best not to routinely lift more than a quarter of your weight alone.
Wide and super-wide format fabric rolls often weigh hundreds of pounds. When designing (or redesigning) your shop floor for digital textile printing, remember to leave sufficient space that provides enough room for the free movement of the number of people and lifting equipment necessary to perform these tasks safely.
Obviously, the same safety and spatial considerations will also apply to the areas surrounding precoating and post-treatment equipment and processes. You may need to coat fabric in-plant before printing or you may purchase pre-coated fabrics. Textile inkjet printers that use aqueous-based pigmented acrylic polymer inks will need the application of heat or other energy forms to evaporate the water from the ink allowing cross-linking polymerization of the ink binder to occur. Leggett and Platt have developed pigmented UV-cure inks that use UV exposure to initiate polymerization and heat to insure cure. L&P also has developed a type of disperse dye that fixes to receptive fabrics, such as polyester, with exposure to UV-curing lamps. The L&P systems are physically large. Each of these systems requires a minimum access parameter of 1.25-meter width (about 4 feet) for operator movement, equipment maintenance, and the loading and unloading of materials. If using a folklift to position, deliver, and remove fabric bolts, the floor design needs to provide sufficient space to safely maneuver the lift or other material handling devices.
From here to there
One way to insure efficiency of digital textile printing operations is to minimize the distance necessary to move anything. Obviously, the heavier and bulkier the object, such as fabric bolts, the less you will want to move it. Placing fabric bolt storage and staging areas near the loading dock or receiving area, which is adjacent to the bolt coating, printing, and finishing area will conserve personal and mechanical strain. If using a forklift or other motorized device for moving bolts, dedicating a track around or to one side of the printing and processing equipment is a smart safety measure.
Inkjet printing, and particularly aqueous-based inkjet printing associated with fabric printing, requires an operating environment with humidity between 40 and 60 percent RH (relative humidity) and temperatures of about 20 to 22 degrees C. A controlled environment requires enclosure of the processes.
While you want to have bolts near the loading dock, remember to separate loading areas that are exposed to climactic variation from storage and processing areas that require climate control. Also, retain fabric and other substrates in climate-controlled environments for about 24 hours before printing to stabilize fabric temperature and humidity. Fabric containing an excess of moisture can resist the adhesion of ink and thus reduce color intensity.
One step at a time
Inkjet textile printing and processing would seem best performed in-line. Straight line processing, however, is only as fast as the slowest part of the process. Precoating and drying fabric before printing can typically be accomplished faster than traversing print head inkjet printing devices. Postprocessing will also normally require different processing time than printing or precoating and drying.
One pre-coater could feed two or three different print lines, which in turn could feed one or two heating, steaming, or washing processing units. Moreover, many print shops do not have the floor area or configuration to permit linear serial processing. The separation of each processing step would require storage or staging areas for bolts between each process. Economies of enclosed climate-controlled space may suggest that we turn the textile print production process on itself into a “U” pattern.
In planning the digital textile printing shop, do not forget the size, shape, and weight of the equipment that you will be using. If your shop is on the fifth floor of an industrial building with a freight elevator that has limited weight and dimension capacity, you might need to move. I know of a number of situations where a building’s entries required stretching to enable the installation of textile equipment to proceed. If the concrete pad or floor is not rated to hold the equipment you plan to put on it with the vibration it will generate, you may be installing the means to destroy your plant and personnel.
Going with the flow
Equipment suppliers can provide to you all the information for each of the processing devices you use or want to use, including physical dimensions, weight, and other specifications. If your location requires three-phased electricity and you do not have three-phase at your plant, you probably should begin negotiating with your utility company. You may also want to calculate to determine if you have sufficient electrical capacity to operate your print and processing equipment.
Indirect inkjet sublimation and direct inkjet disperse dye printing have gained favor for the printing of banners, flags, and soft signage. Heat transfer fixes sublimation dyes to receptive substrates and does not require washing or additional post-processing. Many flag and banner printers who are directly printing polyester fabrics with disperse dye are heat blooming the printed image without post-process washing. These approaches can greatly reduce the space required for processing.
Printers such as the Mimaki DS-160 and 180, d-gen’s Teleios, and TexPress DSS-1800 provide inkjet direct disperse dye printing solutions for the flag and banner markets. Dupont’s Artistri 2020 and 3320 tacky belt inkjet printing system, Mimaki’s TX printer series, Regianni’s DraEM machine, and Robustelli’s Monna Lisa provide inkjet textile direct printing systems with technical support and plant configuration advice.
Understanding how operators, printing equipment, and processes interact can lead to an informed design for your workflow efficiencies. A more efficient operation is well on its way to becoming a successful shop.