Yankee & MG Cylinder Grinding, Superfinishing and Coating

Restore cylinder geometry, surface condition and production performance

The surface condition and geometry of a Yankee or MG cylinder are critical to paper quality, runnability and reliable production.

Continuous operation, doctoring, corrosion and mechanical wear can gradually result in chatter marks, grooves, scratches, uneven wear, profile deviations and surface deterioration. Even relatively small surface defects can influence the interaction between the cylinder, paper web and doctoring system. Industry sources similarly identify Yankee surface condition as critical to stable production and tissue quality.

PR Rolls provides specialised on-site grinding, superfinishing and coating services for Yankee and MG cylinders.

The cylinder is restored directly at the mill using purpose-built mobile equipment, reducing the need for dismantling, transportation and external workshop repair.

Depending on the cylinder condition, the complete service can include:

Inspection & Measurement → Profile Assessment → Precision Grinding → Superfinishing → Surface Preparation → Thermal Spray Coating → Final Grinding & Finishing → Verification

The objective is not simply to create a smooth surface.

The objective is to restore the geometry and functional surface required for reliable paper production while preserving the cylinder asset for future operation.

Why Yankee and MG Cylinder Surface Condition Matters

Yankee and MG cylinders operate in demanding conditions where the cylinder surface continuously interacts with the paper web and, depending on the application, doctoring systems and process chemistry.

Over time, the cylinder surface can deteriorate through a combination of mechanical wear, corrosion, doctoring and process-related conditions.

Typical problems can include:

• Chatter marks
• Uneven wear
• Profile deviations
• Grooves
• Scratches and dents
• Corrosion
• Surface roughness variations
• Local surface damage
• Doctoring-related wear
• Coating deterioration

These conditions can contribute to problems such as unstable doctoring, sheet defects, web breaks and reduced production efficiency. Surface wear and doctoring conditions can also influence each other, which makes correct diagnosis important before simply regrinding the cylinder.

For this reason, PR Rolls approaches Yankee and MG cylinder maintenance as surface restoration rather than simply material removal.

On-Site Yankee Cylinder Grinding

Restore the cylinder profile and surface without removing the cylinder

Yankee cylinder grinding is used when surface wear or damage has progressed beyond what can reasonably be corrected through normal polishing or surface finishing.

Precision grinding removes controlled amounts of material to restore the required cylinder geometry, profile and surface condition.

This can be required when the cylinder has developed:

• Deep chatter marks
• Uneven cross-machine wear
• Profile deviations
• Corrosion
• Significant scratches or grooves
• Doctoring-related surface damage
• Irregular surface condition

The distinction between polishing and profile grinding is important. Industry practice generally uses polishing for smaller local defects and grinding when deeper defects or loss of the intended cylinder profile need to be corrected.

PR Rolls performs the grinding directly at the customer's mill using equipment designed specifically for on-site cylinder restoration.

Yankee Cylinder Profile Grinding

Surface roughness is only part of the equation

A Yankee cylinder does not only require the correct surface finish. It also needs the correct geometrical profile.

Wear may develop differently across the cylinder face. Over time, this can change the cylinder profile even when parts of the surface still appear relatively smooth.

Polishing alone cannot correct significant geometrical deviations.

PR Rolls can therefore measure and evaluate the cylinder before grinding to determine where correction is required. Material can then be removed in a controlled manner to restore the required profile.

This is particularly important because every grinding operation removes material from the cylinder.

The goal should therefore not be to remove as much material as possible.

The goal is to remove only what is necessary to restore the required cylinder condition.

This lifecycle principle is also reflected in established Yankee maintenance practice, where profile measurements are used to determine the appropriate timing for grinding and minimise unnecessary material removal.

MG Cylinder Grinding

Restore the surface responsible for paper finish

MG – Machine Glazed – cylinders have a different process function from tissue-machine Yankee cylinders, but precise geometry and surface condition are equally important.

The MG cylinder surface contributes to the characteristic smooth and glossy surface produced on one side of MG paper.

Surface deterioration, wear, corrosion, scratches or profile deviations can therefore influence both product quality and machine performance.

PR Rolls provides on-site MG cylinder grinding to restore:

• Cylinder geometry
• Surface profile
• Surface uniformity
• Required surface finish
• Damaged or worn areas

Depending on the required end result, precision grinding can be followed by superfinishing or coating.

The maintenance strategy is adapted according to the cylinder construction, paper grade, existing surface condition and operating requirements.

Superfinishing of Yankee & MG Cylinders

Achieve a highly controlled final surface

Grinding restores cylinder geometry and removes surface defects, but some applications require an even more refined final surface.

PR Rolls provides on-site superfinishing of Yankee and MG cylinders to achieve very smooth and controlled surface characteristics after grinding.

Superfinishing can be used to:

• Reduce microscopic surface irregularities
• Create a highly uniform final surface
• Achieve very low surface roughness where required
• Support consistent contact conditions
• Prepare the cylinder for demanding production conditions
• Produce a mirror-like finish where the application requires it

The required final surface should always be determined according to the actual cylinder application and production conditions.

Superfinishing is therefore not simply a cosmetic finishing operation.

It is the final engineering of the functional cylinder surface.

Thermal Spray Coating for Yankee & MG Cylinders

Create a new functional surface on the existing cylinder

In some cases, continued grinding alone is not the optimum lifecycle solution.

If the cylinder has experienced significant wear, corrosion or repeated grinding, a new functional surface may be required.

PR Rolls provides on-site thermal spray coating for Yankee and MG cylinders.

A correctly engineered coating can provide properties such as:

• High wear resistance
• Corrosion resistance
• Controlled surface hardness
• Long service life
• Stable surface characteristics
• Reduced need for repeated material removal from the original cylinder

The appropriate coating system depends on the cylinder material, existing surface condition, paper grade, doctoring conditions and required surface functionality.

Thermal coating is an established method for Yankee surface restoration and lifecycle extension within the tissue industry.

For PR Rolls, the important principle is:

The coating is not simply a protective layer. It becomes the new functional surface of the cylinder.

Grinding and Coating as One Complete Surface Solution

Applying a coating onto a cylinder with incorrect geometry does not correct the underlying geometrical problem.

For this reason, grinding and coating should be considered as parts of the same restoration process when both are required.

A complete PR Rolls project can include:

1. Inspection and Measurement
Assess the cylinder condition, geometry, wear and visible surface defects.

2. Profile Assessment
Determine whether polishing, grinding, coating or a combination of methods is appropriate.

3. Precision Grinding
Remove damaged surface material and restore the required cylinder geometry and profile.

4. Superfinishing
Create the required final surface characteristics where applicable.

5. Surface Preparation
Prepare the restored cylinder substrate for thermal spray coating.

6. Thermal Spray Coating
Apply the selected functional coating according to the application requirements.

7. Final Grinding and Finishing
Finish the coated surface to the specified geometry and surface condition.

8. Verification
Measure and verify the completed cylinder surface before returning the machine to operation.

This integrated approach allows PR Rolls to manage geometry + surface condition + coating as one complete restoration project.

Polishing, Grinding or Coating – What Does Your Cylinder Need?

Not every Yankee or MG cylinder problem requires the same maintenance method.

The correct maintenance method should always be determined from the actual cylinder condition, construction, operating history and production requirements.

For example, established Yankee service practice differentiates between polishing for smaller defects and profile grinding for more severe surface damage and profile loss.

Yankee Cylinder Surface and Doctoring

The cylinder and doctor blade operate as one functional system
A Yankee cylinder surface does not operate independently.

The surface continuously interacts with the doctoring system, paper web and process conditions.

Changes in cylinder geometry, surface roughness, hardness or coating condition can therefore influence doctoring behaviour. Conversely, incorrect doctoring conditions can contribute to accelerated cylinder wear.

Industry experience shows that alignment and doctoring problems can lead to abnormal Yankee wear and unnecessarily frequent regrinding.

For this reason, surface defects should not always be treated as isolated symptoms.

When recurring wear or chatter occurs, it is important to consider why the damage has developed.

PR Rolls approaches grinding and coating according to the actual operating environment of the cylinder, with the objective of creating a surface suitable for the machine's production and doctoring conditions.

Chatter Marks on Yankee Cylinders

Chatter marks are a common reason for evaluating Yankee cylinder surface restoration.

They can appear as repetitive patterns on the cylinder surface and may influence doctoring, sheet quality and runnability.

The appropriate corrective action depends on their severity.

Minor surface irregularities may sometimes be corrected through polishing or finishing, while deeper chatter marks can require precision profile grinding. Valmet, for example, distinguishes between polishing for slight chatter and profile grinding for more severe defects.

However, simply removing chatter marks does not necessarily address their underlying cause.

If the problem repeatedly returns, the complete operating environment – including doctoring and mechanical conditions – should be evaluated.

The objective should be:

Identify the problem → Restore the cylinder → Reduce the risk of recurrence.

Protecting Yankee & MG Cylinder Lifetime

Think in terms of lifecycle – not individual grinding jobs

Yankee and MG cylinders are major production assets.

Every grinding operation removes material. Maintenance decisions should therefore consider both the immediate surface problem and the remaining lifetime of the cylinder.

PR Rolls' approach is based on a simple principle:

Measure accurately → Remove only what is necessary → Restore the required geometry → Create the required surface → Plan future maintenance

This helps avoid unnecessary material removal while maintaining the surface condition required for reliable production.

Where appropriate, thermal spray coating can create a renewed functional surface and reduce the need to repeatedly remove material from the underlying cylinder.

Lifecycle-oriented Yankee maintenance is also a central approach among major industry suppliers, combining measurement, grinding, coating and condition assessment rather than treating these as isolated interventions.

The goal is not to grind more often. It is to maintain the required cylinder condition while preserving the asset for as long as technically and economically reasonable.

Why Perform Yankee & MG Cylinder Work On-Site?

Yankee and MG cylinders are large, heavy and deeply integrated into the production machine.

Removing such a cylinder for external workshop restoration can involve significant:

• Dismantling
• Heavy lifting
• Transportation
• Workshop lead time
• Reinstallation
• Production downtime

PR Rolls brings specialised equipment and expertise directly to the mill.

Depending on the project, measurement, grinding, superfinishing, surface preparation, coating and final finishing can be performed on-site.

This allows the work to be coordinated with the mill's planned shutdown and avoids unnecessary transportation of the complete cylinder.

Yankee and MG Cylinder Inspection & Measurement

Good surface restoration begins with understanding the actual cylinder condition.

Before determining the maintenance scope, PR Rolls can inspect and measure the cylinder to evaluate factors such as:

• Existing surface condition
• Wear pattern
• Cylinder profile
• Geometry
• Surface damage
• Previous grinding or coating condition
• Required final surface

The measurements provide a basis for deciding whether the cylinder requires finishing, profile grinding, coating or a combination of treatments.

This condition-based approach is particularly important for large cylinders because unnecessary grinding reduces the available material for future maintenance.

External Inspection Area

Internal Inspection Area

When Should a Yankee or MG Cylinder Be Inspected?

An inspection or surface assessment should be considered when the mill observes changes such as:

• Chatter marks
• Visible surface wear
• Corrosion
• Scratches or grooves
• Uneven cylinder profile
• Changes in doctoring behaviour
• Recurring surface defects
• Paper quality variations related to the cylinder surface
• Increased web breaks
• Coating deterioration
• Abnormal or uneven wear patterns
• A planned major shutdown

Recurring problems deserve particular attention.

If a cylinder requires unusually frequent grinding, the underlying cause should be investigated rather than simply repeating the same maintenance operation. Industry case studies demonstrate how mechanical or doctoring-related conditions can otherwise cause repeated premature wear.

Yankee and MG Cylinder Surface Restoration for Different Applications

PR Rolls adapts the restoration process according to the cylinder and its application.

Tissue Machine Yankee Cylinders
Surface geometry, doctoring interaction and functional surface condition are particularly important for tissue production.

MG Paper Cylinders
A highly controlled surface is required to achieve the intended machine-glazed paper characteristics.

Paper and Board Applications
Large drying and glazing cylinders may require grinding, finishing or coating to restore geometry and surface functionality.

Steel and Cast Iron Cylinders
The maintenance and coating strategy must take the cylinder construction and existing surface into account.

The correct solution is therefore determined by the cylinder – not simply by selecting a standard grinding or coating process.

Why Choose PR Rolls for Yankee & MG Cylinder Restoration?

PR Rolls combines several specialist capabilities within one on-site project:

Measurement + Profile Grinding + Precision Grinding + Superfinishing + Thermal Spray Coating + Final Finishing

This allows the cylinder to be evaluated as a complete functional surface rather than treating grinding and coating as unrelated services.

The objective is to help mills:

• Restore cylinder geometry
• Correct surface damage
• Achieve the required surface finish
• Extend cylinder service life
• Reduce unnecessary material removal
• Improve production reliability
• Plan future maintenance
• Reduce downtime through on-site execution

PR Rolls uses purpose-built mobile equipment designed for demanding work directly at the customer's production site. Its current service offering already includes on-site Yankee and MG grinding, coating, inspection, measurement and superfinishing.

Frequently Asked Questions About Yankee & MG Cylinder Grinding

What is Yankee cylinder grinding?
Yankee cylinder grinding is a precision machining process used to remove surface defects and restore the required geometrical profile and surface condition of a Yankee cylinder.

When does a Yankee cylinder need grinding?
Grinding may be required when the cylinder has significant chatter marks, corrosion, wear, grooves, scratches or profile deviations that cannot be adequately corrected through polishing or normal surface finishing.

What is Yankee profile grinding?
Profile grinding corrects geometrical deviations across the cylinder face. The objective is to restore the required cylinder profile while controlling the amount of material removed.

What is the difference between Yankee polishing and grinding?
Polishing or superfinishing is primarily used to improve relatively minor surface irregularities and surface finish. Grinding removes more material and can correct deeper defects and geometrical/profile deviations.

Can a Yankee cylinder be ground on-site?
Yes. PR Rolls performs Yankee and MG cylinder grinding directly at the customer's mill using mobile equipment designed for on-site operation.

What is superfinishing?
Superfinishing is a precision finishing process used after grinding when a very smooth and highly controlled final surface is required. PR Rolls currently offers superfinishing for demanding Yankee and MG cylinder applications.

Why are Yankee cylinders thermally coated?
Thermal spray coating can create a new functional surface with properties such as improved wear and corrosion resistance. Thermal coating is widely used in Yankee lifecycle management to protect the cylinder surface and extend service life.

How does Yankee surface condition affect doctoring?
The doctor blade operates directly against the Yankee surface, so cylinder geometry, roughness, coating condition and wear can influence doctoring behaviour. Incorrect doctoring or alignment conditions can also accelerate cylinder wear.

Can PR Rolls grind and coat the same cylinder?
Yes. PR Rolls can combine measurement, grinding, coating and finishing as one on-site cylinder restoration project.

Does PR Rolls also grind MG cylinders?
Yes. PR Rolls provides on-site grinding, superfinishing and coating services for both Yankee and MG cylinders.

Restore the Surface. Preserve the Cylinder.

A Yankee or MG cylinder does not necessarily need replacement when its surface condition deteriorates.

Through measurement, precision profile grinding, superfinishing and thermal spray coating, the existing cylinder can often be restored directly at the mill.

PR Rolls approaches every project according to the actual condition of the cylinder.

The objective is to determine:

• What needs to be corrected?
• How much material needs to be removed?
• What surface does the process require?
• Would coating extend the useful life of the cylinder?

This turns grinding from an isolated maintenance operation into a planned cylinder lifecycle strategy.

Restore the required geometry. Engineer the right functional surface. Preserve the cylinder for future production.