- February 15, 2012, Timothy J. Walker
Can you pass this 20-question quiz to prove you understand basic principles of web handling?
What if a person called you and wanted to sell you some web handling advice? How would you know they were qualified to offer web handling advice? Is there some test you could give them to check their level of expertise? There wasn’t…until now.
This test isn’t intended to test if someone is a web handling guru but to find out if they understand basic principles and can solve many problems on their own. Although I consider these concepts as web handling fundamentals, I expect even someone with years of experience in web converting may have a difficult time with one or two of these questions. I have had some mercy here; you won’t need your calculator.
1. Tension Control—How do you determine the target web handling tension for a given product in units of force or force per width?
2. Tension Control—Name three causes of tension variations across the web’s width (i.e., things would create a loose edge or center).
3. Tension Control—Name one advantage that using a dancer roller has over a tension load cell roller in a closed-loop tension control system.
4. Tension Control—Name one advantage that using a tension load cell roller has over a dancer roller in a closed-loop tension control system.
5. Tension Control—Name one advantage and one disadvantage of draw control (a.k.a. speed ration control).
6. Rollers—What is a reasonable specification for roller alignment in mm/m, milli-radians, or mils/in.?
7. Rollers—Which rollers in a process likely will have the larger diameter?
8. Traction—When is a nipped roller needed on a driven roller separating two tension zones?
9. Nipped Rollers—What is a simple measurement to determine if two nip rollers are pressing together uniformly?
10. Laminating—If a two-layer laminate product curls to the top layer in the machine direction, which would reduce the curl: increase or decrease the top layer pre-laminate tension?
11. Guiding—For automatic guiding in the middle of a process, which is preferred: a steering-type guide or a displacement-type guide?
12. Web Tracking—In a vertical span, which will cause the web to track off center more, a roller tram or level error?
13. Web Tracking—Name four mechanisms that will cause the web to track off centerline through a series of rollers.
14. Wrinkling—If you see wrinkles at low speeds, but the wrinkles go away at higher speeds, what is the most likely reason?
15. Wrinkling—If a roller is deflecting into a bowed shape due to gravity, which direction is it best NOT to approach that roller if you don’t want to wrinkle: vertically from above, vertically from below, or horizontally?
16. Spreading—Name a spreader or anti-wrinkle roller that does NOT have a rubber surface.
17. Winding—If you center wind at constant torque, what is the percent change in tension if the roll diameter changes from 100 mm to 400 mm?
18. Winding—If you wind a paper and a film product of equal thickness and roll geometry at the same combination of winding conditions (tension, nip, taper, speed), which is likely to have higher internal roll pressures?
19. Winding—Name three advantages of using a nipped or gap-controlled roller ahead of winding?
20. Unwinding—What is an easy way to determine if an unwinding roll is cinching (i.e., some of the roll’s layers are slipping in the machine direction? The answers? I’ve got some in mind, but I’m open to creative thinking. There is always two or three ways to skin a cat.
ANSWERS? Visit Tim's Web Lines new blog.
Web handling expert Tim Walker, president of TJWalker+Assoc., has 25 years of experience in web processes, education, development, and production problem solving. Contact him at 651-686-5400; firstname.lastname@example.org; www.webhandling.com.