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Why It Takes 24 Points to Prove Your Rolls are Round

Posted by Robert Rourke on Mar 13, 2018 11:00:00 AM

Over the years, PRG has reground many rolls originally ground either in-house or by other companies. The story is familiar. That roll was likely ground improperly for one of the following reasons:

  • It was ground on bearings and housings left fixed to the roll.
  • The work was not performed in a temperature-controlled environment.
  • The roll wasn’t set up with the crown positioned properly.

In the instances of rolls ground on bearings, the tolerances of the bearing and housing will not allow the grinder operator the ability to attain the proper shape, roundness or TIR. If the grind was performed in an environment that isn’t temperature controlled, you will also experience variations in the final grind results due to these temperature swings.

All of these instances are avoidable!

Even though those rolls may work for a while, sooner or later, your product will have quality issues. In addition, your equipment will fail… very likely prematurely versus what you really could achieve for roll life.

 

Roundness is Key to Runnability

It’s important to know that your roll will be returned to service and be ground to the exact specification required for your product. PRG guarantees that all work meets all of your production requirements. Not only do we promise if it’s Not in Spec, Don’t Send us a Check, we prove it. Every job we do comes with a Grind Report, which features PRG’s exclusive 24-Point SpecCheck™.

We give you the data that demonstrates your roll will perform optimally, have longer life, and will provide consistent, high-quality output.

PLASTI_5 - specifications measurements precision roll grinding-134964-edited.jpg

PRG’s 24-Point SpecCheck:

Your grind report contains the following data:

1) Cylindrical Profile: We test how close your roll is to a true cylinder. Not a cone, not an oval. Our measurements are done by diameter, not radius.

2) Roll Face Dimensional Diameter

3) Roll Face Dimensional Length

4) Profile Deviation: We determine how your roll’s actual profile differs from the target profile. We measure and report 21 equally spaced sections of your roll.

5) Diameter Deviation: We confirm where matched diameter is required.

6) Concentricity: This is the distance between the center of rotation of the bearing seats and the center of rotation of the roll face.

7-13) TIR: We measure Total Indicated Run-Out at:

  • Both Bearing Seats
  • Both Set-up Diameters
  • Each End of the Roll Face
  • The Center of the Roll Face

14-16) Roundness of the Roll Face: We measure the roll face with two probes at the center as well as at both ends to determine how close the roll is to a perfect circle.

17-18) Bearing Seat Dimensional: We check for diameter and geometry.

19) Hardness of Roll Face

20) Surface Finish of Roll Face

21-22) Side Face Run-Out: Both sides are checked where applicable.

23-24) Perpendicularity: We check the side face to bearing seats as well as the side face to roll face.  

 

Not the Same Old Grind Report

In addition to the 24 Points detailed above, PRG’s Grind Report shows you side-by-side graphs detailing before- and after- grind measurements, proving your roll has been ground to your exact specification.

PRG’s work produces results:

  • Round rolls that resist barring longer and increase runnability
  • Tight tolerances that resist hard spots, caliper variation, moisture streaks and surface finish differences
  • Total Indicated Run-Out (TIR) specification achieved by tolerances up to +/- 20 millionths of an inch.

 

The Data Doesn’t Lie

Why trust your equipment, your investment and your reputation to any roll grinding service who simply cannot prove that your roll is in spec? Trust the experts at PRG.

We’ve got 24 reasons you’ll be glad you did.

 

 Request A Quote Today

Topics: Best Practices, Roll Grinding, Maintenance, Process Improvements

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