Tension Control Questions
1 – Introduction to Tension
- Why is tension important?
- What is web tension?
What are the engineering units of tension?
What are the machine units of tension?
2 – The Right Tension
- What tension is the right tension for a web?
What tension will break or deform a web? - What are recommended tensions by product?
- Why does target tension have such a large safety factor (10:1)?
- When should a web run higher or lower than the default recommended tension?
- What is the right tension for a laminated or coated product?
3 – Mechanics of Tension
- What is stress?
What is strain? - What is the Modulus of Elasticity?
- What is Poisson’s ratio?
When is Poisson’s ratio important? - What is elasticity?
What is viscoelasticity?
4 – Tension Zones
5 – Tension Control Options
- What are the options for creating and controlling tension in a zone?
- What is open-loop tension control?
What is closed-loop tension control?
When is open-loop tension control used?
When is closed-loop tension control used? - What is open-loop torque control?
Why use open-loop torque control?
6 – Drive Points
- What is a drive?
What is a ‘drive point?’
What is a master drive point?
What is a tensioning drive point?
Can a non-roller be a drive point?
When would a roller not be a good drive point? - What is a brake?
What is a clutch?
What are the mechanics of a brake or clutch? - What is a motor?
Why use motors vs. brakes or clutches?
What type of motors are used in web handling? - What determines motor size?
What determine motor cost? - Is it better to control motor speed or torque?
7 – Torque Control
- How does torque create tension?
- How much torque is needed?
- What is a reasonable torque range for a motor, brake, or clutch?
- Why is diameter feedback used with torque control?
How is diameter measured?
8 – Draw Control
- What is draw control?
Why use draw control (open-loop speed ratio control)? - What determines the draw ratio of a machine?
What are the units of draw or speed ratio control? - How does draw control change or create strain?
- How are draw zones time dependent?
- What creates tension variations in a draw zone?
9 – Closed-Loop (Feedback ) Control
- What is load cell feedback tension control?
How do load cell rollers work?
How much wrap angle should a load cell roller have? - What is dancer roller feedback tension control?
What is a dancer roller? How does it work?
What makes a good dancer roller system? - What is better for tension feedback, a load cell or dancer roller?
- What is an accumulator?
Is an accumulator a drive point or a feedback device? - How is a tension control loop tuned?
How fast does a tension loop respond?
10 – Speeds and Lengths