At the end of this module, you will be able to:
- Identify the main components of a QCS scanner
- List the potential benefits of CD profile control
- List safety guidelines for QCS scanners and CD profiling systems
- Identify common locations for QCS scanners
- Identify and describe the types and locations of profiling systems commonly used on paper and board machines
- Describe when manual profile adjustments might be used instead of automatic profile adjustments
- Identify the challenges of CD profile control on modern paper and board machines
The following key questions are answered in this module:
What are the main benefits of improving the uniformity of CD profiles?
The two potential benefits of improved CD profiles are reduced cost and improved runnability.
Why are QCS scanners often installed ahead of size presses?
Sheet moisture is often monitored before a size press because moisture greatly affects the sheet's ability to absorb the sizing solution.
Are QCS scanners installed around coating operations?
Sheet weight is often measured before and after coating operations in order to monitor the applied coat weight and coating uniformity.
Are profiling systems ever installed in dryer sections?
Rewet showers are sometimes installed in dryer sections to flatten the CD moisture profile at the reel.
Why are some profiling adjustments made manually?
Manual profiling adjustments might be made if a system has a limited number of cross-machine zones or if automatic actuators are not available.
Below is a transcript of the video sample provided for this module:
The sheet’s CD weight profile is established at the headbox, where there are two major methods of profiling: slice lip profiling and dilution profiling. Slice lip profiling uses actuators on the slice lip to open or close the slice opening in multiple locations across the machine to increase or decrease the stock flows by zone. This method has been used for decades but has the disadvantage that it controls not only the flow of fiber, but also the flow of water to each zone. This can create cross-flows in the stock after it exits the slice, from higher flow zones to adjacent lower flow zones. The cross-flows lead to non-uniform fiber orientation profiles and problems with related sheet properties, such as curl.
Use the additional resources and links below to learn more about this topic: