At the end of this module, you will be able to:
- Describe the purpose of felt guiding
- Explain the principles of felt guiding
- Identify and describe the main components of a felt guiding system
- Explain why felt tension is important
- Identify and describe the equipment used for felt tensioning
- Explain how felt stretchers can be used to straighten the seam
The following key questions are answered in this module:
Why is it important for press felts to be centered on the machine?
To completely cover the sheet width to ensure uniform water removal in the press nips. Also, to keep the felts from running off the front or back of the machine.
What is the basic principle of fabric guiding?
The basic principle of fabric guiding is that the felt moves or "steers" toward the roll end that it contacts first.
By what mechanism does the movement of the guide palm cause the autoguide to move?
The guide palm movement closes or opens a bleed air valve, which increases or decreases the air supply pressure to an air bag which moves the autoguide end of the guide roll.
What is the purpose of the hand guide or manual guide?
Its purpose is to keep the autoguide end centered in its travel. This ensures that the autoguide always has some adjustment available in both directions.
What is the recommended roll wrap (in degrees) for a felt guide roll?
Guide rolls need to have a roll wrap of 25 to 35 degrees to ensure sufficient friction for the roll to move the felt.
Below is a transcript of the video sample provided for this module:
The auto guide assembly includes a guide palm or guide paddle, to contact the front edge of the felt and monitor its position. One or two air bags or air diaphragms, to control the position of the auto guide roll end, and a bleed air valve to control the supply air flow to one of the air bags. The air bag that is affected by the bleed air valve expands or contracts to move the auto guide roll and with or against the direction of felt travel. A second airbag or a spring is set up to provide a constant positioning force opposite the first airbag.
Use the additional resources and links below to learn more about this topic: