Home Mills & Technologies Maintenance Thwarting Roll Defects

Thwarting Roll Defects

Starts With Identifying Problems That Require Precision Grinding

One of the most important factors in driving profit and maximizing manufacturing efficiency is, ironically, one of the most overlooked elements of your production. Roll defects are commonly left unaddressed, and this leads to a number of costly problems – most notably, factory downtime and hidden costs.

Being able to identify these flaws is a strategic advantage, empowering you to keep your rolls in tip-top shape with precision roll grinding and produce high-quality products.

What are the three biggest roll defects, and how do you identify them?

Roll Defect #1: Barring

The most common roll defect is barring. It occurs on working rolls such as nipped rolls in the press section, size presses, calender stacks and offline calenders.

Barring can be distinguished by end-to-end variations in surface profile running parallel to your roll's center of rotation and perpendicular to its direction of motion. The cross-machine variations are typically three to four inches apart and can be identified in similar sheet variations. Barring is seen most clearly in the form of caliper, tensile strength, gloss or opacity variations.

Increased mechanical vibrations, which ultimately cause material fatigue and damage, are also a common sign of roll barring.

Roll Defect #2: Feedlines

The second most prevalent defect is feedlines, characterized by "barber pole-like" striping or scoring around your rolls. Much like with barring, the same defective property is transferred to your final product, diminishing tensile sheet strength and visual qualities – especially with lightweight paper grades.

Feedlines aren't easy to detect in all cases, though. They're not always visible to the naked eye when a roll is first installed. But within hours or days, they can be seen clearly, and the impact on your product can be significant.

Roll Defect #3: Chatter

Similar to barring, chatter is a roll defect resembling the effects of barring, but with much closer frequency.

If there are very high bars on your roll's face or bearing seat, chances are your rolls are suffering from chatter. Chatter is often hidden on the bearing seat, especially if the bearing is not removed for a routine grind. This chatter will transfer to the face of the roll and cause vibrations, which reduces your product quality.

Address Defects With Precision Roll Grinding

The sooner you identify these roll defects, the sooner you're able to reestablish the production of high-quality products, which your customers demand.

When you do detect an issue, precision roll grinding is an absolute and immediate necessity. The longer you wait, the greater the risk you run of experiencing a larger, more costly problem. Not to mention that, within that time, you're repeatedly producing a low-quality product.

Take steps to proactively identify roll defects and protect your business from the consequences.

Source: Precision Roll Grinders

 
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