Willey explains how to maximize efficiency in your screen department.
By Jane Willey
|Table 2: Sample Shop Information for Calculating the Screen Loop|
|Press(M)||Number of colors printing (C)||Frame size (in inches)||Setups/shift (SU)|
|machine A 8/c auto||6||23 X 31||3|
|machine B 8/c auto||6||23 X 31||3|
|machine C 10/c auto||8||30 X 43||3|
|machine D 10/c auto||8||30 X 43||3|
|machine E 10/c auto||8||30 X 43||3|
|machine F 10/c auto||8||30 X 43||3|
The floor plan shown in Figure 3 is approximately 4000 sq ft and will accommodate a screen-loop range of 300-600, producing 100-200 screens per shift. Figure 4 shows a typical distribution of frames in the loop. The numbers in Figure 4 are a centerline, and during a production day, all areas will be in constant flux. The screen department in this example would employ six to 12 people. The floor plan follows the process for the loop and is based on using carts for transporting and storing screens with virtually no built-in racking or drying. The size and number of equipment pieces such as carts, sinks, exposure units, work stations, and light tables are totally dependent on the number and dimensions of screens in the loop. This plan also assumes the use of pin registration for the art and preregistration of film positives to the screen.
|Figure 4: typical distribution of frames in the screen loop|
|Retensioning through stretching||5%||20|
|Drying and stretched storage||20%||80|
|Coating through coated storage||20%||80|
|Preregistration through production prep||7%||28|
Improving productivity In any screen department, you will have a range of efficiency based on labor, process technique, and automation that will allow you to maximize efficiency for a given space. For example, if your print production initially dictates a screen loop of 300 frames with four employees producing 100 completed screens per shift, but you purchase a new press that expands your loop to 420 frames with an increase in daily screen output of 160, you can meet the increased production by adding personnel in key areas, improving your process techniques, or both. Certainly, any of the hands-on steps in the process (e.g., reclaiming, degreasing, coating, preregistration, and stretching) are all areas where more people will generate more screens--provided there is adequate space for additional work stations. Multiple sinks, exposure units, stretching tables, etc., will all boost screen production, but usually require physical expansion of the screen department. Other ways to increase screen output without a physical expansion or additional personnel involve improving your current process or automating steps in the loop. Using carts to transport screens and hot rooms for drying rather than built-in storage and drying cabinets will dramatically reduce the number of times individual frames must be handled. It will also provide quicker drying times without sacrificing the integrity of the finished screen. Both carts and hot rooms reduce the incidence of screen breakage. Pin registration of film positives speeds up preregistration placement of film to screen. Automated reclaiming lines and automatic coaters will standardize results and speed up the process as well. However, just as a move from manual printing to automatic printing requires minimum volume and careful economic analysis to justify equipment investment, so does a decision to automate your screenmaking process. Efficiency = profitability As the sophistication of images and presses requires tighter screen tolerances, I am sure we will continue to see a trend to update and streamline the screenmaking process. It will not matter how well your art department performs or how many printing presses you have. If the screen department is not balanced in capability and quantity, you will not achieve the efficiency you strive for. After all, the screen is the translating link between the original art image and the final printed product--which, in the end, is the key to your profitability. About the author Jane Willey is a technical consultant specializing in prepress and printing techniques, as well as procedural and quality-control systems. During her 20-plus years in the screen-printing industry, she has worked as a designer, production supervisor, and prepress specialist. She has also contributed a variety of articles on production and management topics and frequently speaks on these subjects at industry trade events.
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