Yankee Dryer Dry Creping Basics
The Yankee dryer is a large, steam-heated, pressure vessel that is used in the production of tissue grades. After the tissue sheet is dried by the Yankee dryer and Yankee hoods to its final moisture target, it is creped and removed from the Yankee by the creping doctor. The “dry creping” process is responsible for the bulk, stretch, and softness that are desirable in tissue grades. This course describes what happens to the sheet during dry creping, factors that influence dry creping results, the design and operation of the creping blade, and blade angles and sheet angles associated with the creping blade.
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Course Details
Learning Objectives
• The dry creping process
• The differences between wet crepe and dry crepe
• Creping blade setup and geometry
Specs
Frequently Asked Questions
What is dry creping?
What sheet properties are affected by the creping process?
What factors affect crepe quality?
What is the blade wear angle?
What is the creping pocket angle?
Sample Video Transcript
The last important angle is the creping angle or pocket angle, which is defined as the angle between the Yankee tangent line and the creping blade surface. The crepe pocket angle is very important in determining the resulting crepe structure in the sheet. Crepe pocket angles typically range from 65 to 95 degrees. It is interesting to note that during production, the creping angle is actually determined by the blade wear angle and the blade grind angle. The relationship between them is described by this equation, creping angle equals 90 degrees minus blade wear angle plus blade grind angle. This means that the creping angle can be increased by either increasing the blade grind angle or decreasing the blade wear angle.
