CD Profile Control
QCS scanners are used to monitor key sheet properties at one or more locations on modern paper and board machines, and report average values, standard deviations, and MD and CD profiles. The CD profile data can be used to make automatic or manual adjustments at one or more profiling systems. Because sheet properties can be affected by more than one profiling system, profiling actuator adjustments can affect multiple sheet properties, and sheet shrinkage and sheet wander occur, it can be challenging to coordinate CD profiling efforts. [course outline] QCS Reel Scanners Scanner Sensors Benefits of CD Profile Control 1 of 2 Benefits of CD Profile Control 2 of 2 MD vs CD Variation Safety Guidelines 1 of 2 Safety Guidelines 2 of 2 QCS Scanner Locations Fabric Profiles Profiling Actuator Locations Headbox S
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Learning Objectives
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
Specs
| Course Level | Intermediate |
| Languages | English |
| Compatibility | Audio, Video |
| Based on: | Industry Standards and Best Practices |
Key Questions
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.
Sample Video Transcript
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.
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