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3M Mill Rolls
Squeegee Analysis of Industrial Rolls

The squeegee or wringer performance of an industrial roll is the most important factor to many users. In general, wringer rolls should remove as much solution as possible from the surface o the metal coil being processed. The type and temperature of the solution, the line speed and the pressure on the roll will all affect the wringer performance in a real application. For comparison purposes, the tests were run at 600 fpm line speed and at specified roll pressure (PLI) and water temperature depending on the roll density and durometer. Further, with the laboratory squeegee test we try to learn much more about the roll performance than just the wringing ability.

The lab squeegee performance test is a 48 hour test which can be broken into five areas of data collection and study. As mentioned, the parameters of water temperature, line speed and pressure on the roll are defined. The data collected during this test is the amount of water carry out from the roll nip measured in grams. The data presentation is a graph of the water carry out weight vs. The time of the test from 0 to 48 hours. The five test areas are:

  1. When the test is started, the water weight is measured at 0 hours, 2 hours, 4 hours and 8 hours. This provides a picture of whether or not the roll requires a "break in" period.

  2. The 23 hour data point indicates how the roll performs under good conditions.

  3. Then the roll is damaged with a specific tool and time routine to simulate a problem on the production line. The water weight immediately after damage measures the impact of the damage. (the 24 hour data point)

  4. Again measurements are taken after 2, 4 and 8 hours (at 26, 28 and 32 hours) to show how the roll recovers or heals itself after the damage while running at normal operating conditions.

  5. A final reading is taken at 48 hours to indicate the performance of a roll which has not been repaired after a damage incident.

Several graphs are included which show a comparison of the squeegee performance of specific rolls as follows:

Figure 1. 5N, Toho and United Rotary Brush rolls.
All between 81 and 82 Shore A durometer.

Figure 2. RK, Toho and United Rotary Brush rolls.
The RK is 88 Shore A durometer, but more comparably priced.

Figure 3. 5N, RK, Toho and United Rotary Brush rolls.
All 4 rolls of Figures 1 and 2. A complicated graph, but all on one page.

Figure 4. 5N, RK, 5C and 5A rolls.
This compares the four 3M rolls - "5" density and RK.

Figure 5. 7N and RK rolls.
This compares the RK to a Neutral roll of similar durometer.

Figure 6. 7N, RK, 7C and 7A rolls.
This compares the four 3M rolls - "7" density and RK.

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The first three Figures compare 3M rolls to competitive rolls available from Toho and United Rotary Brush Co. Important points to note include:

* The 5 N roll has the best wringer performance throughout the entire test.

* The impact of the damage on the 5N roll is far less than the other rolls.

*** Figure 1 shows the Toho roll to pass at least twice as much water as the 6N roll, both before and after damage (210% before damage and 200% after damage).

*** Also, the URB roll passes 54% more water than the 6N roll before damage and 87% more water than the 5N roll after the roll is damaged.

*** Figure 2 shows the harder RK roll (88.1 Shore A) to be comparable with the softer Toho and URB rolls (81.9 and 81.1 Shore A respectively).

*** After 23 hours of running, the water carry out amount is within a range of 8%.

*** The right half of Figure 2 shows that the RK roll has a lower effect from the damage procedure and maintains better wringer performance as the rolls "heal" from the damage.

*** Figure 3 is a combination of Figures 1 and 2 showing all four rolls: 5N, RK, Toho and United Rotary Brush.

*** The 5N roll and the URM roll show no "break in" period.

*** The RK roll and the Toho roll do show a "break in" period.

Figures 4, 5 and 6 compare the four different 3M rolls - Neutral, RK, Acid and Type C - in 5 and 7 density. Again, please note:

* The Neutral rolls demonstrate the best wringer performance across the board.

* The 7N roll is the best wringer roll before damage and compares with the 5N roll after damage.

* The RK durometer is closer to a 7N, but the wringer performance is more like a 5N.

* The Type C rolls squeegee better than the Acid rolls in 5 and 7 density.

* The RK, 5C and 5A rolls all show a "break in" period.

* The 7 density rolls do not show a significant "break in".

* This Type C and Acid roll performance is in water. The wringer performance may improve when these rolls are used in the chemical solutions that they were designed to withstand.

* Be sure to note the graph scale differences on the water weight axis (20, 40 and 80).

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