TecnoDiamond – Extreme Wear-Resistant Coating for Rolls & Dryer Cylinders

Hard carbide surface for demanding wear and heavy doctoring applications

Industrial rolls and cylinders operating under high mechanical loads require more than a conventional surface coating.

Continuous doctoring, scraping, abrasive wear, corrosion and demanding production conditions can gradually damage the roll or cylinder surface, resulting in more frequent grinding, increased maintenance and reduced component lifetime.

TecnoDiamond is PR Rolls' extremely hard and wear-resistant carbide coating for rolls and cylinders operating in demanding industrial applications.

Originally developed for applications such as calender and press rolls, TecnoDiamond is also used on paper machine dryer cylinders where the surface must withstand aggressive or heavy doctoring.

With a specified hardness of approximately 1400 ±100 HV, TecnoDiamond creates a dense, wear-resistant and corrosion-free functional surface designed for long-term operation.

PR Rolls combines TecnoDiamond with its expertise in precision grinding, thermal spraying, surface finishing and doctoring solutions, providing a complete surface solution rather than coating alone.

More Than a Coating – A Complete Surface Solution

The performance of a roll or dryer cylinder does not depend on the coating alone.

The underlying geometry must be correct, the coating must suit the operating conditions and – particularly on doctored dryer cylinders – the doctoring system must be compatible with the surface.

PR Rolls therefore approaches TecnoDiamond applications as a complete surface engineering solution:

Precision Grinding + TecnoDiamond Coating + Surface Finishing + Doctoring Solution

Depending on the application, the project can include inspection, measurement, grinding, coating, finishing and optimisation of the doctoring conditions.

This approach addresses both the mechanical condition of the component and the operating conditions of its functional surface.

What Problems Does TecnoDiamond Solve?

TecnoDiamond is primarily intended for applications where wear resistance and surface durability are critical.

Typical problems include:

• Rapid roll or cylinder surface wear
• Heavy doctoring or scraping
• Abrasive operating conditions
• Frequent regrinding
• Surface scoring
• Corrosion
• Loss of surface quality
• Short maintenance intervals
• Premature roll surface deterioration
• High lifecycle costs

Instead of repeatedly grinding an unprotected surface, TecnoDiamond creates an extremely hard carbide layer designed to protect the underlying roll or cylinder.

The objective is to extend surface lifetime and increase the interval between major maintenance operations.

Where is TecnoDiamond Used?

TecnoDiamond is suitable for industrial rolls and cylinders where a very hard, durable surface is required.

Key applications include:

• Dryer cylinders exposed to heavy doctoring
• Calender rolls
• Press rolls
• MG cylinders
• Other rolls and cylinders exposed to high wear
• Applications requiring a hard, smooth surface
• Components exposed to abrasive mechanical contact

The coating and final surface specification should always be selected according to the actual process conditions. 

See also TecnoDiamond FS

TecnoDiamond for Dryer Cylinders

A hard coating for cylinders exposed to demanding doctoring
Dryer cylinders are an important application for TecnoDiamond when surface durability and resistance to doctoring wear are more important than non-stick characteristics.

Doctor blades continuously interact with the cylinder surface to remove fibres, deposits and other contaminants.

In particularly demanding positions, the doctoring conditions can create significant mechanical wear.

This may gradually lead to:

• Surface wear
• Scratches and scoring
• Uneven cylinder surfaces
• Increased grinding requirements
• Shorter maintenance intervals
• Damage to the underlying cylinder

TecnoDiamond provides a very hard carbide surface capable of withstanding demanding mechanical doctoring conditions.

This makes it a particularly relevant solution for dryer cylinders where conventional surfaces or softer functional coatings do not provide sufficient wear resistance.

Designed for Heavy Doctoring

Doctoring is essential for keeping many dryer cylinders clean, but it also creates continuous mechanical interaction between the doctor blade and cylinder surface.

The more aggressive the doctoring conditions, the greater the demands on the surface.

TecnoDiamond's high hardness makes it suitable for applications where the cylinder must tolerate continuous or heavy doctoring without rapid surface deterioration.

This is an important distinction between TecnoDiamond and PR Rolls' release-oriented coatings.

The primary purpose of TecnoDiamond is:

Extreme hardness → wear resistance → resistance to doctoring → long surface lifetime

rather than maximum non-stick performance.

Industry experience supports the importance of considering coating and doctoring together. Voith, for example, has tested hard cylinder coatings under doctor loads significantly above normal operating levels when evaluating wear resistance.

Grinding + TecnoDiamond + Doctoring

Treating the complete dryer cylinder surface system
PR Rolls does not consider the dryer cylinder coating independently from cylinder geometry and doctoring.

For demanding TecnoDiamond dryer applications, three elements should work together.

1. Precision Grinding
The cylinder surface is inspected and, where necessary, ground to restore the required geometry and remove wear, corrosion, scratches or previous surface damage.

2. TecnoDiamond Coating
The restored cylinder receives the extremely hard carbide coating required to withstand the mechanical operating conditions.

3. Doctoring Solution
The doctoring conditions are matched to the coated surface to achieve effective cleaning without unnecessary blade or surface wear.

The objective is not simply to make the cylinder harder.

It is to create a durable cylinder surface and doctoring combination designed for the actual machine conditions.

Why Doctoring and Coating Must Be Considered Together

The doctor blade and cylinder surface form a continuously interacting system.

Factors such as:

• Blade material
• Blade loading
• Line pressure
• Blade angle
• Holder condition
• Pressure distribution
• Cylinder surface roughness
• Coating hardness

can all influence doctoring performance.

An extremely hard surface does not eliminate the need for correct doctoring.

Instead, the doctoring solution should be selected to work with the TecnoDiamond surface.

This can help achieve:

• Reliable cylinder cleaning
• Controlled doctor blade wear
• Reduced cylinder surface wear
• More predictable maintenance intervals
• Stable surface conditions
• Longer coating lifetime

Valmet's dryer-section examples similarly demonstrate that cylinder surface condition, roughness, blade selection and doctoring parameters need to be considered together rather than as isolated maintenance issues.

TecnoDiamond for Calender Rolls

Calender rolls require precise geometry and excellent surface quality.

Wear, scratches or other surface defects can affect both roll performance and the quality of the finished paper or board.

TecnoDiamond was originally developed specifically for demanding calender and press roll applications, where its extremely hard surface helps increase the interval between regrinding operations.

For calender applications, TecnoDiamond provides:

• Extremely high surface hardness
• Excellent wear resistance
• Smooth final surface
• Corrosion protection
• Extended grinding intervals
• Protection of the underlying roll

The coating can be finished to a very smooth surface, with PR Rolls specifying surface quality down to Ra 0.02–0.2 µm.

TecnoDiamond for Press Rolls

Press rolls are exposed to mechanical loads, moisture and continuous operation.

Where surface wear is a limiting factor, TecnoDiamond can provide a hard protective surface designed to extend the operating lifetime of the roll.

The coating is particularly relevant where the main objective is:

• Increased wear resistance
• Reduced surface degradation
• Corrosion protection
• Longer intervals between grinding
• Stable surface quality

PR Rolls currently identifies press rolls alongside calender rolls as a primary TecnoDiamond application.

TecnoDiamond for MG Cylinders

TecnoDiamond can also form part of a surface solution for demanding MG cylinder applications.

MG cylinders require high surface quality, precise geometry and reliable interaction between the cylinder surface, paper and doctoring system.

PR Rolls has practical experience using TecnoDiamond in an MG cylinder conversion.

In a 2025 project at Lenk Paper, the work included pre-grinding, local repairs, intermediate coating and grinding to a defined crown, followed by TecnoDiamond application after diamond-belt grinding. The reported coating hardness was approximately 1,200 ±100 HV for that project specification.

This illustrates an important aspect of PR Rolls' approach: TecnoDiamond can form part of a larger engineered cylinder restoration rather than simply being applied as an isolated coating.

Extreme Wear Resistance

The defining characteristic of TecnoDiamond is its hardness.

PR Rolls' standard published TecnoDiamond specification states:

Hardness: 1400 ±100 HV

The hard carbide surface is designed to resist mechanical wear significantly better than an untreated roll or cylinder surface.

This makes TecnoDiamond particularly valuable where the component experiences:

• Abrasive wear
• Doctor blade contact
• Scraping
• Mechanical surface loading
• Repeated cleaning
• High production demands

The objective is a surface that maintains its functional condition for longer.

A Modern Alternative to Hard Chrome

High-performance carbide coatings provide an attractive alternative to traditional hard chrome plating in applications where wear resistance, hardness and corrosion protection are critical. Modern HVOF and HVAF thermal spray technologies make it possible to produce dense carbide coatings with excellent mechanical properties while avoiding many of the environmental and process-related disadvantages associated with hard chrome plating.

Carbide-based coatings such as WC-CoCr and Cr₃C₂-NiCr have increasingly been used as hard chrome alternatives because of their combination of high hardness, significantly improved wear resistance and excellent corrosion resistance. The transition is also supported by regulatory and environmental considerations: hexavalent chromium (Cr6+), traditionally associated with hard chrome processes, is carcinogenic, and chromium compounds used in hard chrome plating have been subject to increasingly strict regulation under the EU REACH framework.

Modern high-kinetic thermal spray processes also enable the use of finer carbide and powder particle sizes. Compared with conventional HVOF processes, newer-generation HVAF technology can produce a denser coating microstructure while its lower flame temperature helps limit carbide dissolution during spraying.

For demanding rolls and cylinders, this makes carbide coating technology particularly relevant where the objective is to achieve a hard, dense and wear-resistant functional surface with long service life. For TecnoDiamond applications, these characteristics are especially valuable on calender rolls, press rolls and dryer cylinders exposed to heavy doctoring and mechanical wear.

Longer Intervals Between Grinding

Repeated grinding gradually removes material from a roll or cylinder.

Reducing the frequency of grinding can therefore provide both maintenance and lifecycle benefits.

TecnoDiamond was specifically developed to lengthen the intervals between grinding operations on demanding roll surfaces.

Potential benefits include:

• Fewer grinding operations
• Longer maintenance intervals
• Reduced shutdown requirements
• Less removal of base material
• Extended roll or cylinder service life
• Lower lifecycle maintenance costs

The actual lifetime depends on the application, doctoring conditions, mechanical loads and process environment.

Dense Carbide Coating with HVAF/HVOF Thermal Spray

TecnoDiamond is applied using HVAF/HVOF thermal spray technology.

HVAF – High Velocity Air Fuel – accelerates coating particles at high velocity toward a correctly prepared substrate.

PR Rolls states that its HVAF process produces a dense and highly wear-resistant coating, supporting longer intervals between grinding operations.

For demanding roll and cylinder applications, the resulting carbide layer provides a combination of:

High hardness + density + wear resistance + corrosion protection

This makes thermal spraying an effective way to change the functional surface properties of an existing component without replacing the complete roll or cylinder.

The Development of Fine-Particle Carbide Coatings

Thermal spray technology continues to develop towards finer carbide particles, smaller powder particle sizes and increasingly dense coating structures. Fine-particle or “flash carbide” spraying can enable thinner coatings and lower as-sprayed surface roughness, which in suitable applications can reduce the amount of subsequent grinding and finishing required. Finer coating powders and dense microstructures can also contribute to improved corrosion resistance.

For industrial roll and cylinder applications, these developments demonstrate why modern carbide coatings are increasingly relevant when evaluating alternatives to conventional hard chrome surfaces. The combination of wear resistance, hardness, corrosion protection and advanced thermal spray technology enables the functional surface to be engineered according to the actual operating conditions of the component.

Corrosion Protection

Mechanical wear is not the only threat to industrial roll and cylinder surfaces.

Moisture, process chemicals and operating environments can also contribute to corrosion.

PR Rolls specifies TecnoDiamond as a corrosion-free coating, providing protection of the underlying component in addition to mechanical wear resistance.

Combining wear and corrosion protection can be particularly valuable for components expected to remain in operation for long periods between major maintenance interventions.

Precision Grinding Before Coating

A high-performance coating requires a correctly prepared component underneath it.

If a roll or cylinder has:

• Incorrect geometry
• Wear
• Scratches
• Scoring
• Corrosion
• Previous coating damage
• Surface irregularities

these issues should be addressed before the final functional coating is applied.

PR Rolls can therefore combine precision grinding with TecnoDiamond coating.

Grinding restores the required geometry and creates the foundation for subsequent surface preparation and thermal spraying.

For dryer cylinders, PR Rolls already performs grinding and coating directly in the paper machine, avoiding unnecessary cylinder removal.

Precision Surface Finishing

Hardness alone does not define a high-quality roll coating.

The final surface must also meet the functional requirements of the application.

TecnoDiamond can be finished to a very smooth surface, with PR Rolls specifying:

Surface quality: Ra 0.02–0.2 µm

Depending on the component, final finishing can be adapted to the requirements of the roll, cylinder and process.

This is particularly important for calender, MG and other applications where surface quality can directly influence the production process.

On-site TecnoDiamond Application

One of PR Rolls' major advantages is the ability to perform demanding coating work directly at the customer's site.

This is particularly valuable for large rolls and cylinders that would otherwise require significant dismantling, lifting and transportation.

PR Rolls' on-site dryer cylinder concept allows grinding and coating to be performed directly in the paper machine. Multiple cylinders can also be processed during the same shutdown.

Benefits include:

• Reduced dismantling
• Less transportation
• Reduced heavy lifting
• Shorter maintenance lead times
• Existing components can be restored instead of replaced
• Grinding and coating can be coordinated
• Doctoring can be considered as part of the solution
• Faster return to production

The Complete PR Rolls TecnoDiamond Delivery

Depending on the application, a TecnoDiamond project can include:

1. Condition Assessment
Evaluation of the roll or cylinder, existing surface and operating problem.

2. Precision Measurement
Measurement of geometry, runout, surface condition and other relevant parameters.

3. Grinding
Restoration of the required roll or cylinder geometry.

4. Surface Preparation
Preparation of the substrate for thermal spraying.

5. TecnoDiamond Coating
Application of the hard carbide coating using HVAF thermal spray technology.

6. Precision Finishing
Grinding and polishing to achieve the required final geometry and surface characteristics.

7. Doctoring Solution
For doctored cylinders, the doctoring conditions can be adapted to work correctly with the TecnoDiamond surface.

8. Final Verification
The completed surface and component geometry are inspected and verified.

The exact scope is always determined according to the component and process requirements.

TecnoDiamond vs. Release Coatings

This is an important distinction for customers choosing between PR Rolls coating technologies.

TecnoDiamond is primarily a wear-resistant hard coating.

TecnoClean and TecnoCeraHybrid are primarily designed around release and non-stick performance.

A simplified selection principle is:

This helps customers select a coating according to the actual operating problem rather than simply the component name.

For a dryer cylinder suffering primarily from sticking and release problems, TecnoCeraHybrid may be the more appropriate solution.

For a dryer cylinder where heavy doctoring and mechanical wear are the dominant challenges, TecnoDiamond may be the better choice.

When Should You Consider TecnoDiamond?

TecnoDiamond should be considered when the primary challenge is mechanical surface wear.

Typical indicators include:

• Dryer cylinders are subjected to heavy doctoring
• Cylinder surfaces wear rapidly
• Rolls require frequent regrinding
• Doctoring causes scratches or surface deterioration
• Calender roll surface quality deteriorates too quickly
• Press rolls experience significant wear
• Corrosion affects the underlying surface
• Existing surfaces do not provide sufficient hardness
• Maintenance intervals need to be extended

The correct coating should always be selected according to the actual operating conditions.

PR Rolls can evaluate the component, wear mechanism, existing surface and doctoring conditions before defining the complete surface solution.

TecnoDiamond Technical Properties

PR Rolls' currently published standard TecnoDiamond specifications are:

The exact coating and finishing specification should be determined according to the individual application.

Why Choose PR Rolls for TecnoDiamond?

PR Rolls combines surface engineering with on-site machining and paper machine expertise.

The objective is not simply to apply the hardest possible coating.

It is to understand why the existing surface is failing and create the correct combination of:

Geometry + Coating + Surface Finish + Doctoring

Depending on the application, PR Rolls can provide:

• Condition assessment
• Precision measurement
• On-site grinding
• Surface repairs
• HVAF thermal spraying
• TecnoDiamond coating
• Precision finishing
• Doctoring solutions
• Field balancing
• Final verification

This enables the complete roll or cylinder surface to be addressed within one coordinated project.

Frequently Asked Questions About TecnoDiamond

What is TecnoDiamond?
TecnoDiamond is PR Rolls' hard carbide coating for industrial rolls and cylinders. It is designed for demanding applications where high wear resistance, corrosion protection and long surface lifetime are required.

Can TecnoDiamond be used on dryer cylinders?
Yes. TecnoDiamond is used by PR Rolls on dryer cylinders where high surface durability is required, particularly in positions exposed to demanding or heavy doctoring.

Why use TecnoDiamond on a dryer cylinder?
TecnoDiamond is particularly relevant when mechanical wear from doctoring or scraping is the dominant surface problem. Its extremely hard carbide surface provides greater resistance to wear and helps protect the underlying cylinder.

Is TecnoDiamond a release coating?
Its primary function is wear resistance rather than maximum release. Where sticking and paper release are the dominant problems, a release-oriented coating such as TecnoCeraHybrid or TecnoClean may be more appropriate.

How hard is TecnoDiamond?
PR Rolls specifies a standard hardness of 1400 ±100 HV.

How smooth is the TecnoDiamond surface?
PR Rolls specifies a surface quality range of Ra 0.02–0.2 µm, allowing the coating to be finished to a very smooth, mirror-like surface.

How thick is TecnoDiamond?
The published standard coating thickness is 100–250 µm.

Can TecnoDiamond extend intervals between grinding?
Yes. This is one of the original objectives of the coating. Its high wear resistance is designed to extend the interval between grinding operations.

Can PR Rolls grind the cylinder before coating?
Yes. PR Rolls provides on-site dryer cylinder grinding and coating and can restore the cylinder geometry before the functional coating is applied.

Does doctoring need to be considered when selecting a dryer cylinder coating?
Yes. Doctoring conditions and coating characteristics interact continuously. Blade material, loading, surface roughness and coating wear resistance should therefore be considered together. This system-level relationship is also reflected in industry experience from Valmet and Voith.

Does PR Rolls only provide the coating?
No. PR Rolls can provide a complete surface solution including inspection, measurement, grinding, coating, finishing and, for doctored applications, the appropriate doctoring solution.

Extreme Wear Resistance for Demanding Roll & Cylinder Applications

When mechanical wear is the problem, surface durability becomes critical.

TecnoDiamond provides an extremely hard carbide surface for rolls and cylinders exposed to demanding operating conditions, including dryer cylinders subjected to heavy doctoring, as well as calender and press rolls.

But PR Rolls' solution goes beyond the coating itself.

By combining precision grinding, TecnoDiamond coating, surface finishing and the appropriate doctoring solution, PR Rolls addresses the complete functional surface – helping customers extend maintenance intervals, protect critical equipment and achieve reliable long-term performance.