Metsä Board is investing again at its Kemi mill in Finland, but this time the project is not about adding another block of paperboard capacity.

The company will modernise the board machine winder during Kemi’s annual maintenance shutdown in October–November 2026, targeting better product quality, production efficiency and delivery reliability.

The Metsä Board Kemi winder investment comes three years after the completion of a much larger development programme that raised the mill’s white kraftliner capacity to approximately 465,000 tonnes per year.

For corrugated packaging customers, the significance lies further downstream than the paperboard machine itself.

A mill may be capable of producing hundreds of thousands of tonnes of kraftliner, but that production still has to be wound, slit and prepared consistently into reels that customers can actually run.

That makes finishing equipment a less visible—but commercially important—part of mill reliability.

The Investment Focuses on the End of the Board Line

Metsä Board has not disclosed the value of the new investment or detailed technical specifications for the winder rebuild.

What the company has confirmed is that the project is intended to improve three areas:

product quality, operational stability and production efficiency.

Tomi Seppä, VP of the Kemi Board Mill, said the modernisation will strengthen finishing operations and support more consistent product quality and dependable deliveries.

Those objectives are closely connected.

The board machine does not produce the final customer reel in one step.

A large machine reel still needs to move through finishing equipment where it is converted into the widths, diameters and reel configurations required by corrugated board producers.

If finishing capacity or reliability does not keep pace with board-machine output, downstream operations can restrict how efficiently the mill converts production into finished inventory.

Metsä Board has not said the existing winder is currently a production bottleneck, so that should not be assumed.

But the decision to modernise it shows that the company sees further value in strengthening the finishing stage after earlier investments increased Kemi’s overall production capability.

Kemi Already Went Through a Major Upgrade

The latest project should be viewed as a continuation of a longer modernisation cycle at the mill.

Metsä Board completed a €110 million development programme at Kemi in 2023.

That programme increased annual white kraftliner capacity from around 425,000 tonnes to 465,000 tonnes, while also targeting energy and water efficiency.

The work was not limited to the paperboard machine.

Metsä Board also upgraded finishing and material-handling operations, including:

• increased winder capacity;
• automatic transfer of machine reels from the board machine to the winder;
• fully automated reel loading;
• and a new logistics chain connecting production with the deep-water port at Ajos.

That makes the 2026 winder modernisation particularly interesting.

Rather than representing an isolated equipment replacement, it appears to form part of the continued optimisation of an already-expanded production system.

The mill has increased its output capability.

Now Metsä Board is continuing to work on how efficiently and reliably that output moves through finishing and toward customers.

Why a Winder Matters to Corrugated Packaging Customers

For someone outside papermaking, a winder can look like relatively simple downstream equipment.

In practice, it sits at an important point between board production and customer delivery.

The Kemi linerboard machine has a trim width of 6.73 metres, operates at speeds of up to approximately 950 metres per minute, and produces grades from roughly 125 to 250 g/m². The mill operates one slitter winder and one rewinder.

That wide parent reel ultimately has to become smaller reels suited to individual corrugators and converting operations.

Finishing therefore has to manage factors including:

reel dimensions;

web tension;

edge quality;

winding consistency;

reel hardness;

and reliable handling at high throughput.

The exact scope of Metsä Board’s 2026 rebuild has not been disclosed, so it would be inappropriate to claim which of these individual parameters the investment will change.

But they illustrate why finishing quality matters.

A corrugated packaging producer does not buy theoretical board-machine capacity.

It buys reels that need to unwind consistently and move through downstream equipment without unnecessary disruption.

For customers, that is where mill reliability becomes practical.

Kemi Supplies a Large Global Kraftliner Market

The scale of the operation also raises the importance of finishing reliability.

Metsä Board describes Kemi as the world’s largest production facility for coated white-top kraftliner, with annual capacity of 465,000 tonnes.

The material is used as the outer surface layer in corrugated packaging, including packs for:

consumer electronics;

household appliances;

food and beverages;

fruit and vegetables;

retail packaging;

and shelf-ready applications.

The white coated surface provides the printable face of the corrugated structure, while the kraftliner construction contributes to packaging performance.

That means consistency matters both visually and mechanically.

A producer supplying branded corrugated packaging cannot evaluate linerboard only by tonnes delivered.

Printing performance, surface consistency and runnability also influence how that material performs at the corrugator and during subsequent printing and converting.

For a mill operating at Kemi’s scale, even small improvements in finishing stability can therefore have consequences across substantial customer volumes.

North America Is Also Important for Kemi

The mill is not serving only European corrugated converters.

Metsä Board has a long history of selling its Kemi white-top kraftliners into the Americas, dating back to the launch of Kemiart in the U.S. market in 1991.

Its current portfolio includes MetsäBoard Classic WKL, Pro WKL and Prime WKL.

Company information also indicates that Europe and North America are major market regions for its white kraftliner business.

That makes supply reliability particularly relevant.

A reel delivered to a customer several thousand kilometres from Finland has already passed through a longer logistics chain than material consumed close to the mill.

Production scheduling, finishing availability, port handling and ocean transport therefore all have to work together.

A production disturbance at the finishing stage can potentially affect not just mill inventory but downstream export schedules.

This helps explain why Metsä Board is explicitly connecting a winder investment with supply-chain reliability, rather than describing it simply as an equipment upgrade.

The Timing of the Upgrade Is Also Important

The work will be carried out during the mill’s scheduled annual maintenance shutdown in October–November 2026.

No additional standalone production shutdown has been announced specifically for the winder project.

At the same industrial site, Metsä Fibre is also planning substantial work at its Kemi bioproduct mill during October–November.

Metsä Fibre has announced a roughly six-week investment shutdown related to renewal of the bioproduct mill’s cooking area, with annual maintenance taking place during the same period.

The two mills are operationally linked.

Metsä Fibre’s Kemi bioproduct mill supplies pulp and energy to the Metsä Board operation, while Metsä Board also operates its own 180,000-tonne unbleached pulp line integrated at the site.

Metsä Board has not stated that the two investment projects were specifically coordinated for logistical reasons.

But the overlapping shutdown period demonstrates how maintenance and capital projects at an integrated pulp-and-board site can involve more than an individual machine.

This Is About Getting More From Existing Capacity

The most useful distinction in the latest announcement is between capacity investment and productivity investment.

In 2023, Kemi’s development programme added approximately 40,000 tonnes of white kraftliner capacity.

The 2026 announcement does not identify another increase in nominal output.

Instead, Metsä Board is focusing on operating stability, quality and efficiency.

For paper and board producers, those investments can become increasingly important after a major expansion.

Once a machine has more theoretical capacity, the next question is whether all downstream stages can consistently support it.

Stock preparation.

Board machine.

Coating.

Winding.

Reel handling.

Warehousing.

Port logistics.

Improving one section without considering the others can simply move the operational constraint somewhere else.

That does not mean Kemi currently has such a constraint.

Metsä Board has not reported one.

But the company’s investment sequence illustrates a broader mill-management principle:

adding production capacity and extracting reliable production from that capacity are not the same investment decision.

Finishing Operations Often Receive Less Attention Than Paper Machines

Large paper and board machine rebuilds naturally attract attention.

They involve wider machines, higher speeds, new forming sections, dryers, coaters or major capacity additions.

Finishing investments tend to receive less publicity.

Yet customers ultimately interact with the product created after those final operations.

A damaged reel.

Inconsistent winding.

Poor edges.

Unreliable reel dimensions.

Or delays in converting machine reels into customer orders can all reduce the value generated by an otherwise efficient board machine.

That means the commercial return from a winder modernisation is not necessarily measured only through additional tonnes.

It can also come through:

higher operating availability;

more predictable output;

less finishing disruption;

more consistent customer reels;

and better alignment between board-machine production and shipment schedules.

Metsä Board has not quantified those expected benefits for this project, so no specific efficiency gain should be assumed.

But they explain why a company with a recently upgraded high-capacity machine would continue investing downstream.

Kemi’s Investment Strategy Has Shifted From Expansion to Optimisation

Viewed over several years, Kemi shows a clear investment sequence.

First came the larger development programme.

Capacity increased to 465,000 tonnes.

Water consumption per tonne was targeted to fall by approximately 40%.

Energy consumption per tonne was targeted to decrease by around 5%.

Finishing automation and logistics were expanded.

Now comes another winder modernisation focused primarily on consistency and reliability.

This resembles the next stage of asset development after a major capacity project:

make the expanded system work more predictably rather than simply making it bigger again.

That is relevant across the pulp and paper sector.

With large greenfield machines and major rebuilds requiring significant capital, producers do not always need another headline capacity project to improve competitiveness.

Smaller targeted investments in bottleneck removal, automation, quality control and finishing reliability can potentially improve how effectively existing assets are used.

What Corrugated Converters Should Watch

For customers buying Kemi white-top kraftliner, the main question is not the value of Metsä Board’s investment.

That figure has not been disclosed.

What matters more is what changes after the upgraded winder returns to service.

Converters should watch for improvements in areas such as:

reel consistency;

delivery reliability;

availability of required reel specifications;

production stability following the shutdown;

and whether the modernised finishing operation supports more predictable lead times.

Those are the areas most closely connected to the objectives Metsä Board has actually stated.

It will also be worth watching whether this modernisation is followed by additional finishing automation or logistics investments at Kemi.

The company has not announced further projects at this stage.

Before Your Next Mill Investment, Look Beyond the Main Machine

There is a useful lesson here for paper and board producers planning their own capital programmes.

Take your production line and follow the material after it leaves the paper machine.

How long does a machine reel wait before winding?

Where does finishing capacity sit relative to machine output?

How often does downstream equipment interrupt production or shipment schedules?

Which stage determines whether a finished reel actually reaches the warehouse on time?

And is the equipment generating the most tonnes necessarily the equipment creating your biggest operational risk?

A new paper machine naturally attracts attention.

But once capacity is installed, competitiveness increasingly depends on whether every downstream stage can support it consistently.

Metsä Board’s Kemi investment is a reminder that the last machine before the customer can matter almost as much as the machine making the board.

For a 465,000-tonne kraftliner mill supplying corrugated packaging around the world, strengthening that final link may be more valuable than adding another headline capacity figure.

Last Updated on 03/09/2026 by Jota Machinery