PROdry Technology Inc.

Example 1	Edge Damage
Example 2	Circumferential Groove
Example 3	Multiple Surface Flaws

Yankee Topography

Circumferential Groove

Wear on the surface of a Yankee dryer can be the source of serious runnability problems in papermaking. There are several possible causes for exaggerated wear, but localized problems need to be addressed promptly to maintain the best production rates. In this example, a Yankee exhibited a circumferential groove around the dryer which was causing sheet marking and picking. PROdry Technology was asked to quantify the surface distortion and lend insight as to the cause of the flaw.

The Yankee surface topography in the region of the groove is shown in the accompanying figure. The deepest areas on the shell within the groove appear as four blue spots in the figure. The groove itself is indicated by the yellow contour. Doctor blade wear patterns indicated that non-uniform blade wear was the source of this surface wear. A grind was scheduled and completed. Data from the surface measurements were used to estimate the amount of material to be removed during the grind, allowing for optimum scheduling of other work by the mill.