On-site Milling Services for Heavy Industry

Precision milling of large machine structures directly at your site

PR Rolls provides specialised on-site milling services for large industrial machinery, structures and critical mounting surfaces. Using portable milling equipment, our specialists restore flatness, geometry and dimensional accuracy directly where the equipment is installed.

Our on-site milling services are used in demanding industrial environments including pulp and paper mills, steel and metal plants, power generation, shipyards, marine applications and other process industries.

Wear, corrosion, deformation and mechanical damage can gradually affect machine beds, division planes, mounting plates, frames, rails and sealing surfaces. Even relatively small deviations can compromise alignment, sealing and machine reliability.

By performing precision milling directly on-site, PR Rolls helps customers restore critical equipment without unnecessary dismantling or transportation – reducing maintenance time and helping production return to operation faster.

What is On-site Milling?

On-site milling, also known as in-situ milling, field milling or portable milling, is precision machining performed directly where the equipment is installed.

Instead of dismantling a large machine or component and transporting it to a workshop, PR Rolls brings specialised portable machining equipment and field service expertise to the customer's site.

On-site milling can be used to restore or modify:

• Flatness
• Parallelism
• Mounting surfaces
• Sealing surfaces
• Division planes
• Machine beds
• Bed plates
• Frames
• Rails
• Contact surfaces
• Keyways
• Critical dimensions and geometries

This approach is particularly valuable for large, heavy or production-critical equipment where dismantling and transportation would be costly, time-consuming or technically challenging.

Why Precision Milling Matters

Large industrial machines depend on accurate geometry.

Machine components must be correctly positioned and supported to ensure reliable operation. When critical surfaces become worn, damaged or distorted, the effects can extend far beyond the damaged area.

Typical consequences may include:

• Misalignment
• Poor sealing
• Steam or process leakage
• Uneven mechanical loading
• Increased vibration
• Premature component wear
• Installation problems
• Reduced machine reliability
• Unplanned production interruptions

PR Rolls uses precision milling to restore the required geometry and create accurate reference, contact and mounting surfaces.

Typical On-site Milling Applications

PR Rolls performs milling for a wide range of industrial components and structures.

Typical applications include:

• Division planes
• Machine mounting plates
• Machine beds
• Engine beds
• Bed plates
• Basic rails
• Crane rails
• Machine frames
• Sealing surfaces
• Contact surfaces
• Keyways
• Large structural components

These applications are consistent with PR Rolls' existing field experience, which includes milling of division planes, mounting plates, engine beds, bed plates, rails and frames.

Division Plane Milling

Restore flatness, contact and sealing performance
Division plane milling is an important application for PR Rolls' on-site machining technology.

Division planes require accurate contact between adjoining machine sections. Corrosion, wear, deformation or previous repairs can result in uneven surfaces and poor sealing.

Depending on the equipment, this can contribute to:

• Steam leakage
• Process leakage
• Poor sealing
• Uneven contact
• Alignment problems
• Mechanical stress
• Reduced equipment reliability

PR Rolls machines division planes directly at the customer's site to restore the required surface geometry and flatness.

The work can be combined with precision measurement before and after machining to verify the achieved result.

Machine Bed & Bed Plate Milling

Machine beds and bed plates provide the foundation for accurate equipment installation.

If these surfaces become worn, damaged or distorted, the equipment installed on them may no longer have the correct support or alignment.

PR Rolls provides on-site machine bed and bed plate milling to restore accurate mounting and reference surfaces.

Typical applications include:

• Equipment rebuilds
• Worn bed plates
• Damaged mounting surfaces
• Installation of replacement equipment
• Alignment corrections
• Foundation modifications
• Repairs following mechanical damage

Portable milling allows these large structures to be restored without transporting them to an external workshop.

Machine Mounting Surface Milling

Correct mounting surfaces are essential when installing or realigning industrial machinery.

PR Rolls can machine existing mounting surfaces to restore:

• Flatness
• Surface condition
• Correct installation level
• Contact between components
• Parallelism
• Required dimensional geometry

This is particularly valuable during equipment installation, modernisation and rebuild projects, where existing foundations or machine structures need to be adapted for new or modified machinery.

Frame Milling

Large industrial frames can require precision machining following wear, repairs, structural modifications or equipment rebuilds.

PR Rolls performs on-site frame milling where critical contact, reference or mounting surfaces need to be restored.

Applications can include:

• Large machine frames
• Equipment support structures
• Bearing mounting areas
• Contact surfaces
• Rebuilds
• Structural modifications
• New equipment installations

Portable machining equipment makes it possible to accurately machine structures that would otherwise be difficult or impractical to transport.

Keyway Milling & Repair

Keyways are critical for locating components and transmitting torque between shafts and connected machine parts.

Wear or damage can result in excessive clearance, poor fit or reduced mechanical reliability.

PR Rolls provides on-site keyway milling and repair for large industrial components.

Depending on the project, the work can include:

• Machining new keyways
• Restoring worn keyways
• Modifying existing keyways
• Repairing damaged surfaces
• Correcting keyway geometry
• Final dimensional verification

Performing the work on-site can eliminate the need to remove large shafts or components solely for workshop machining.

Rail & Crane Rail Milling

PR Rolls also has experience in basic rail and crane rail milling.

Accurate rail geometry and supporting surfaces are important for correct positioning, movement and load distribution.

On-site milling can support:

• New rail installation
• Rail replacement
• Alignment correction
• Foundation repair
• Rebuild projects
• Restoration of damaged mounting surfaces

Portable milling equipment enables long surfaces and large structures to be machined directly in their installed environment.

Milling of Sealing and Contact Surfaces

Reliable industrial equipment often depends on accurate contact between mating surfaces.

Corrosion, erosion, distortion or mechanical damage can compromise flatness and cause leakage.

PR Rolls can restore critical sealing and contact surfaces using precision on-site milling.

Applications can include surfaces affected by:

• Steam leakage
• Process leakage
• Poor gasket contact
• Uneven sealing pressure
• Mechanical damage
• Surface distortion

Restoring the existing surface can often provide a faster and more cost-effective alternative to replacing a large component.

On-site Milling for Power Generation

Power plants contain large production-critical machinery where accurate alignment, mounting and sealing surfaces are essential.

PR Rolls' broader on-site machining services support power-generation applications involving shafts, flanges, sealing faces, bearing areas, frames and other large components.

On-site milling can be used as part of:

• Turbine maintenance and overhauls
• Generator maintenance
• Machine bed restoration
• Division plane machining
• Foundation and mounting surface repairs
• Sealing surface restoration
• Equipment installation and alignment projects

Performing the work at the power plant helps minimise dismantling and allows machining to be integrated into the planned outage.

On-site Milling for Steel & Metal Industry

Steel and metal production equipment operates under high mechanical loads and demanding operating conditions.

Machine frames, mounting surfaces, rails and other structures may gradually develop wear or dimensional deviations.

PR Rolls provides on-site machining for steel and metal industry customers, where large equipment often needs to be repaired in its installed position. PR Rolls identifies steel and metal production as one of the industrial sectors served by its on-site operations.

Potential milling applications include:

• Machine frames
• Bed plates
• Mounting surfaces
• Rails
• Bearing mounting areas
• Large structural components
• Equipment rebuilds

On-site Milling for Shipyards & Marine Industry

Large marine and shipyard components can be particularly difficult to transport for machining.

PR Rolls provides on-site machining for shipyards and marine applications, where portable equipment allows large components and structures to be restored at their operating or installation location.

On-site milling can support:

• Machinery installation
• Machine bed restoration
• Frame machining
• Mounting surface correction
• Flange and contact surface restoration
• Alignment-related repairs
• Rebuild and modification projects

Reducing dismantling and heavy lifting can significantly simplify large marine maintenance projects.

On-site Milling for Pulp, Paper & Board Industry

Pulp, paper and board production remains an important application area for PR Rolls.

Large production machines depend on accurate machine beds, frames, mounting surfaces and division planes. Uneven surfaces or misalignment can affect sealing, machine geometry and production reliability.

PR Rolls' existing milling experience includes problems with division planes, machine bed plates and keyways where deviations may contribute to steam leaks and sealing-face leakage.

Typical applications include:

• Division planes
• Machine beds
• Bed plates
• Mounting plates
• Frames
• Rails
• Sealing surfaces
• Rebuild and modernisation projects

These services complement PR Rolls' wider expertise in grinding, coating, measuring and balancing for pulp and paper production.

Precision Measurement Before Milling

Successful milling begins with accurate measurement.

Before machining starts, PR Rolls can determine the existing geometry and establish reliable machining reference points.

Depending on the application, measurements may include:

• Flatness
• Parallelism
• Level
• Alignment
• Surface position
• Dimensional deviations
• Reference geometry

The measurement results help determine the required machining scope and minimise unnecessary material removal.

Verification After Milling

The machining result should be measurable and verifiable.

After milling, final measurements can confirm that the required geometry and dimensional accuracy have been achieved.

Verification may include:

• Flatness
• Parallelism
• Level
• Alignment
• Surface geometry
• Dimensional accuracy

This provides customers with a clear basis for subsequent assembly, alignment and return to operation.

On-site Milling During Planned Shutdowns

Maintenance shutdowns and industrial outages are often tightly scheduled.

Transporting a large machine component to an external workshop can add significant dismantling, lifting, logistics and reinstallation work.

With portable milling equipment, the component can instead be repaired where it stands.

Key advantages include:

• Reduced dismantling
• Reduced heavy lifting
• Less transportation
• Shorter maintenance lead times
• Machining in the installed environment
• Coordination with other maintenance work
• Faster return to operation

Reducing downtime is a core reason behind PR Rolls' wider on-site machining concept.

Planned Maintenance, Rebuilds & Emergency Repairs

PR Rolls' on-site milling capabilities can support different maintenance situations.

Planned Maintenance
Restore worn or damaged surfaces during scheduled shutdowns before they develop into larger problems.

Major Overhauls
Restore critical geometry during turbine, machine or production equipment overhauls.

Rebuilds and Modernisations
Modify existing machine structures to accommodate new equipment or changed operating requirements.

Equipment Installation
Machine accurate mounting and reference surfaces for new or replacement machinery.

Emergency Repairs
Restore damaged surfaces directly at the customer's site when workshop repair would cause excessive downtime.

This flexibility makes portable milling suitable for both planned lifecycle maintenance and time-critical industrial repairs.

Our On-site Milling Process

1. Inspection & Assessment
The equipment, damage, existing geometry and technical requirements are evaluated.

2. Precision Measurement
Reference points and existing dimensional conditions are established.

3. Machining Plan
The required material removal, target geometry and machining sequence are defined.

4. Equipment Installation
Portable milling equipment is installed and accurately aligned directly at the site.

5. Precision Milling
The surface is progressively machined to the required dimensions and geometry.

6. Final Measurement
The completed surface is measured and verified against the project requirements.

7. Additional Maintenance
Where required, other machining, measuring, grinding, coating or balancing work can be coordinated within the same maintenance project.

More Than Milling – Complete On-site Machining

Milling is often one part of a larger industrial repair.

PR Rolls provides a broad range of on-site machining and maintenance services for heavy industry, including:

• Milling
• Turning
• Grinding
• Drilling
• Grooving
• Precision measuring
• Coating
• Field balancing

PR Rolls' wider on-site machining service is designed for large machinery in industries ranging from pulp and paper to power generation, steel and marine applications.

Combining several services through one partner can reduce the number of contractors involved and help streamline maintenance execution.

Why Choose PR Rolls for On-site Milling?

PR Rolls has roots in on-site machining stretching back to the 1980s, when the company's founders began developing solutions for demanding repairs of large production machinery directly at customer sites. The expertise was subsequently expanded from paper industry applications to power generation and other large-scale industries.

Today, customers benefit from:

• Decades of on-site machining experience
• Specialised portable milling equipment
• Experience with large industrial machinery
• Division plane milling
• Machine bed and bed plate milling
• Mounting surface restoration
• Frame milling
• Rail machining
• Precision measurement and verification
• Multiple machining capabilities from one partner
• Support for planned shutdowns and urgent repairs
• Reduced dismantling and transportation requirements

Our objective is not simply to remove material.

PR Rolls restores the flatness, geometry, alignment and contact conditions required for reliable industrial operation.

Frequently Asked Questions

What is on-site milling?
On-site milling is precision machining performed directly where industrial equipment is installed. Portable milling machines allow large components and structures to be restored without transporting them to a conventional workshop.

Is on-site milling the same as portable or in-situ milling?
These terms are commonly used for the same general approach: bringing machining equipment to the installed component rather than removing the component for workshop machining.

What can PR Rolls mill on-site?
PR Rolls' documented applications include division planes, machine mounting plates, engine beds, bed plates, basic rails, crane rails and frames.

Which industries use on-site milling?
PR Rolls provides on-site machining services across industries including pulp and paper, steel and metal, power generation, shipyards/marine and other heavy process industries.

Why use on-site milling instead of workshop machining?
For large equipment, on-site milling can reduce dismantling, lifting and transportation requirements. This can shorten maintenance lead times and enable repairs to be completed within planned shutdowns.

Can PR Rolls mill division planes?
Yes. Division plane milling is one of PR Rolls' documented applications. It can be used to restore uneven surfaces that affect contact and sealing.

Can PR Rolls mill machine beds and bed plates?
Yes. PR Rolls performs milling of machine beds and bed plates to restore critical mounting surfaces.

Can milling help with alignment?
Yes. Milling can restore the flat and accurate reference or mounting surfaces required for correct equipment alignment. The actual cause of an alignment problem should first be assessed and measured.

Can PR Rolls measure the surface before and after milling?
Yes. Measurement and verification form part of PR Rolls' broader on-site machining process and can be used to establish the initial condition and verify the finished result.

Can milling be combined with other on-site services?
Yes. Depending on the project, PR Rolls can combine milling with turning, grinding, drilling, grooving, measurement, coating and field balancing.

Restore Critical Machinery Directly On-site

Large industrial equipment does not always need to be dismantled or transported to a workshop when critical surfaces become worn, damaged or distorted.

PR Rolls provides precision on-site milling for power plants, steel and metal plants, pulp and paper mills, shipyards and other heavy industries, restoring machine beds, division planes, mounting surfaces, frames, rails and other critical structures directly at the customer's site.

By combining portable milling, precision measurement and other specialised on-site machining services, PR Rolls helps industrial customers restore critical geometry, reduce maintenance downtime and extend the service life of existing equipment.