Page 180 - Root Cause Failure Analysis

168 Root Cause Failure Analysis

Figure 13-5 Narrow strip concentrates load toward the center of the roll.

INSTALLATION
The proper installation of process rolls is critical. As with all other machines, align-
ment and proper bolting techniques are extremely important. Misalignment can cause
poor quality, reduced capacity, and premature failure.

Single Rolls
With the exception of steering rolls, all single rolls in a continuous-process line or
conveyor system must be perpendicular to the centerline of the belt, strip, or conveyed
product (i.e., passline) and have the same elevation on both the operator and drive
sides. Any misalignment, either horizontal or vertical, influences the tracking of the
belt, strip, and conveyed product.

Figure 13-6 illustrates a roll that has uneven elevation, or is vertically misaligned.
With this type of misalignment, the strip will have greater tension on the side of the
roll with the higher elevation, forcing it to move toward the lower end. In effect, the
roll becomes a steering roll, forcing the strip, belt, or product to one side of the center-
line of travel.

Paired Rolls
Rolls designed to work in pairs (e.g., scrubber, corrugator, or printing rolls) must be
perpendicular and level to the passline. In addition, they must be parallel to each