On-site Vacuum Roll Drilling for Paper and Board Machines

Precision drilling for dryer section optimisation and improved runnability

PR Rolls provides specialised on-site drilling and vacuum roll drilling services for paper and board machines.

Our drilling services are particularly used in dryer section rebuilds and optimisation projects where existing rolls and cylinders need to be modified for new web stabilizers, vacuum systems or other runnability improvements.

By performing precision drilling directly at the mill, PR Rolls helps customers modify existing equipment without unnecessary dismantling or transportation. Projects can be completed during planned shutdowns and coordinated with other dryer section maintenance and modernisation activities.

PR Rolls works together with technology partners such as Runtech in paper machine rebuild and optimisation projects.

Vacuum Roll Drilling for Paper Machines

Vacuum roll drilling is used to create or modify the hole pattern in rolls so that vacuum can be applied through the roll surface.

The vacuum helps control the paper web and support it against the dryer fabric during critical transfer points in the machine.

PR Rolls performs precision drilling of existing rolls directly at the paper mill, allowing rolls to be modified as part of dryer section rebuilds and runnability improvement projects.

Typical projects include:

Drilling of existing rolls for vacuum applications
Modification of vacuum roll hole patterns
Drilling related to new web stabilizer installations
Conversion of existing rolls for new operating requirements
Dryer section rebuilds and modernisations
Drilling during machine geometry modifications

The drilling pattern and technical requirements are defined according to the specific machine configuration and optimisation project.

Drilling for Web Stabilizer Installations

Modern paper machines require stable web control, particularly at higher production speeds.

In the dryer section, uncontrolled airflow and insufficient web support can contribute to sheet flutter, unstable release, wrinkles and web breaks.

Web stabilizers use controlled negative pressure to help the paper web follow the dryer fabric instead of the cylinder surface during critical opening nips.

When new stabilizers are installed, existing rolls or cylinders may need to be modified to create the required vacuum conditions.

PR Rolls provides the on-site drilling required for these installations, working together with technology suppliers and the customer's maintenance organisation.

Supporting Dryer Section Runnability

The purpose of vacuum roll drilling is not simply to create holes in a roll.

The drilling forms part of a larger system designed to improve how the paper web moves through the dryer section.

Correctly implemented vacuum and web stabilization solutions can contribute to:

Improved web stability
Reduced sheet flutter
Fewer web breaks
Improved sheet release
Reduced unsupported draws
Easier tail threading
Increased machine speed potential
More stable production

For this reason, vacuum roll drilling should be planned as part of the complete dryer section configuration rather than as an isolated mechanical modification.

Dryer Section Rebuilds and Modernisations

Vacuum roll drilling is frequently required when an existing dryer section is rebuilt or modernised.

Instead of replacing existing rolls, it may be possible to modify them on-site for new stabilisation or vacuum requirements.

A typical project can include:

Evaluation of the existing dryer section
Definition of the required machine modifications
Engineering of the drilling pattern
Preparation of existing rolls or cylinders
Precision on-site drilling
Installation of stabilizers and related equipment
Inspection and verification
Start-up support

This approach enables existing machine components to be adapted to new technology while reducing the need for major component replacement.

Precision On-site Drilling

Drilling large rolls and cylinders requires accurate positioning and controlled execution.

PR Rolls uses specialised on-site equipment to perform drilling directly at the machine.

Depending on the project, the work may involve:

Large numbers of precisely positioned holes
Defined drilling patterns
Specific hole diameters
Modification of existing hole patterns
Drilling around existing machine structures

Careful preparation and accurate execution are essential to ensure that the modified component functions according to the engineering specification.

Drilling of Existing Vacuum Rolls

Vacuum rolls may require modification when machine operating conditions or production requirements change.

PR Rolls can modify existing vacuum rolls by drilling additional holes or adapting the existing hole pattern according to the project specification.

This can be required when:

New stabilizers are installed
Vacuum requirements change
Machine speed is increased
Dryer section geometry is modified
Existing equipment is modernised
Runnability improvements are implemented

Modifying an existing roll can provide a cost-effective alternative to manufacturing and installing a completely new component.

On-site Drilling During Planned Shutdowns

Paper machine shutdowns are tightly scheduled.

PR Rolls plans drilling projects around the customer's available maintenance window and coordinates the work with other contractors and technology suppliers involved in the rebuild.

Performing the drilling directly at the mill provides several advantages:

No unnecessary roll transportation
Reduced dismantling
Existing rolls can be modified
Shorter project lead times
Efficient shutdown execution
Coordination with stabilizer installation
Faster return to production

For larger projects, the work can be planned across several rolls or dryer groups during the same shutdown.

Cooperation with Runtech

PR Rolls cooperates with Runtech Systems in paper machine dryer section optimisation and rebuild projects.

Runtech specialises in paper machine runnability solutions, including web stabilizers, pocket ventilation, vacuum systems and machine geometry modifications.

PR Rolls contributes specialised on-site machining and drilling expertise, including the modification and drilling of rolls required for vacuum and stabilizer installations.

Together with the technology supplier and mill maintenance organisation, this enables existing dryer sections to be modified efficiently during planned shutdowns.

Web Stabilization and Vacuum

Web stabilization is particularly important in the first dryer groups, where the paper web can be sensitive to airflow and unstable release.

A controlled negative pressure on the dryer fabric side helps keep the paper web attached to the fabric instead of following the smooth dryer cylinder surface.

The required vacuum depends on factors such as:

Machine speed
Dryer section configuration
Web properties
Dryer fabric
Stabilizer design
Machine geometry

Vacuum roll drilling can form an important part of creating the required conditions for effective web stabilization.

Pocket Ventilation and Dryer Section Optimisation

In double-felted dryer sections, runnability and drying performance are also influenced by the conditions inside the dryer pockets.

Pocket ventilation is used to remove humid air and introduce controlled dry supply air into these areas.

When dryer sections are modernised, web stabilization, pocket ventilation, roll relocation and vacuum roll drilling may therefore form part of the same optimisation project.

PR Rolls supports these projects with the required on-site machining and drilling work.

Benefits of Vacuum Roll Drilling

When implemented as part of a correctly engineered dryer section optimisation project, vacuum roll drilling can support improvements such as:

Better web control
Improved dryer section runnability
Reduced web breaks
Reduced unsupported draws
Improved tail threading
Increased speed potential
More stable production
Better utilisation of existing equipment

The exact results depend on the paper machine configuration and the complete stabilisation and vacuum solution.

More Than Drilling

One of PR Rolls' key strengths is our ability to combine drilling with other specialised on-site services.

Depending on the project, PR Rolls can provide:

Precision measurement
On-site drilling
On-site machining
Grinding
Coating
Field balancing
Final verification

This allows customers to coordinate several mechanical modifications and maintenance activities through one experienced on-site service partner.

Our On-site Drilling Process

1. Project Planning
The machine configuration, engineering specifications and required modifications are reviewed together with the customer and technology supplier.

2. Measurement and Positioning
The roll or cylinder is measured and the required drilling pattern is accurately positioned.

3. Equipment Installation
Specialised portable drilling equipment is installed and aligned directly at the machine.

4. Precision Drilling
The required holes are drilled according to the specified dimensions and pattern.

5. Deburring

6. Grinding

7. Possible Coating

8. Balancing

9. Inspection
The completed drilling work is inspected and verified.

10. Installation and Commissioning Support
PR Rolls can coordinate its work with stabilizer installation, dryer section modifications and other shutdown activities.

Why Choose PR Rolls for On-site Drilling?

PR Rolls combines specialised paper industry expertise with extensive experience in on-site machining of large rolls and cylinders.

Our customers benefit from:

Experience in paper and board machine dryer sections
Specialised vacuum roll drilling
Precision on-site machining equipment
Experience with large rolls and cylinders
Cooperation with leading paper machine technology suppliers
Integration with dryer section optimisation projects
Measurement and verification capability
Efficient shutdown execution
Grinding, coating, machining and balancing expertise from the same service partner

Our role is not simply to drill holes. We ensure that the required mechanical modifications are executed accurately and efficiently as part of the complete machine optimisation project.

Frequently Asked Questions

What is vacuum roll drilling?
Vacuum roll drilling is the precision drilling or modification of holes in a roll to enable vacuum to act through the roll surface. In paper machines, this can be used as part of web stabilization and dryer section optimisation.

Why are rolls drilled when installing web stabilizers?
Depending on the stabilizer and dryer section configuration, existing rolls may need to be modified so that the required vacuum conditions can be created for improved web support and runnability.

Can existing rolls be converted into vacuum rolls?
In suitable applications, existing rolls can be modified through precision drilling according to the engineering requirements of the project. This can reduce the need to replace the complete roll.

Can PR Rolls drill vacuum rolls directly at the paper mill?
Yes. PR Rolls specialises in on-site drilling, allowing rolls and cylinders to be modified directly at the mill during planned shutdowns.

Does PR Rolls work with Runtech?
Yes. PR Rolls cooperates with Runtech in dryer section optimisation and rebuild projects where PR Rolls provides specialised on-site machining and drilling expertise.

Can vacuum roll drilling improve paper machine runnability?
Vacuum roll drilling can form part of a web stabilization solution designed to improve web control, reduce sheet flutter and web breaks, and support more stable dryer section operation.

Can drilling be performed during a planned shutdown?
Yes. PR Rolls plans drilling projects around the customer's shutdown schedule and can coordinate the work with stabilizer installation and other dryer section modifications.

Does PR Rolls provide other on-site machining services?
Yes. PR Rolls provides a range of on-site services including drilling, machining, grinding, measurement, coating and field balancing.