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Mesh Movement and Its Impact on Screen Tension, Part Two

(April 2003) posted on Thu Oct 29, 2015

Dr. Anderson's sage advice still rings true today with this flashback to 2003.

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By John Anderson

Continuing his exploration of mesh tension loss, Dr. Anderson focuses on optimizing stretching procedures to consistently produce stable, high-tension screens. Learn how to minimize thread deflection and achieve predictable mesh-tension levels, whether you use a pneumatic or mechanical stretching system with rigid frames or rely on retensionable frames for both stretching and printing.

Part of this series revealed new findings about the way in which mesh threads interact during and after screen stretching. The article introduced the phenomena of thread deflection and realignment and explained how these conditions lead to unpredictable drops in mesh tension that continue long after initial stretching. Now, the discussion moves from the theoretical to the practical by reviewing common tensioning tools and techniques and assessing their effectiveness in overcoming thread deflection. On the following pages, you’ll discover how to adjust your own tensioning methods to get stable, high-tension screens time after time.

What Is the Optimum Mesh-Stretching Process?
There is no single component you can add or action you can take to completely eliminate mesh deflection (Figure 1) from the screen-stretching process. However, you can cost effectively produce screens with stable, consistent, and repeatable tension levels by modifying your stretching procedures with various functions and options.

[Figure 1: Mesh Deflection
When tensioning screen mesh, friction between intersecting mesh threads causes bowing of the threads, particularly those located toward the center of each screen edge. When other forces are introduced to the mesh, these friction bonds may be broken, allowed the deflected threads to straighten in a process called fiber realignment. This realignment of threads leads to tension loss.]

An optimum mesh-stretching process would apply even tension through controlled extension of each and every thread that makes up a screen. It would produce no sideways deflection of threads and maintain the mesh count of the screen fabric. And it would produce stable, high-tension screens very quickly and inexpensively, with minimal environmental risk and no image-distortion or registration issues. Unfortunately, this is not the perfect world in which such a stretching system could exist. So you must make compromises in your existing mesh-stretching methods, adding new steps to the procedure and, if your situation warrants it, upgrading to more effective stretching technologies. Before you can enhance your stretching methods, however, you should understand the inherent strengths and weaknesses of all the techniques commonly used today.


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