Seamlessly integrated storage and logistics

Stora Enso is a leading global provider of renewable solutions in packaging, biomaterials, wooden constructions and paper. They employ some 26 000 people in more than 30 countries. 1 300 of those employees work at the company’s Imatra mills.

The Imatra mills are located in Southern Finland where they have two production units, Kaukopää and Tainionkoski producing chemical pulp and consumer board. Together they are one of the largest consumer board producing entities in the world, exporting over 90% of their produce to Europe and Southeast Asia. Together they produce some 1 155 000 tons of consumer board, 1 020 000 tons of pulp and 285 000 tons of plastic coating each year.

Meeting changing needs

In 2016 Imatra mills decided to increase their production capacity for extrusion-coated products, and to further enhance their position as a leading global supplier of premium paperboards. Alongside the new polyethylene (PE) coating plant Stora Enso also made the decision to invest in a new automated roll warehouse.

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Before this investment decision was made Stora Enso’s Imatra mills had to utilize outside warehouses in the region to store their intermediate roll buffer due to space limitations in the warehouse at the mills which used the traditional clamp truck warehouse concept. This meant multiple clamp truck handling phases between the base paper production, PE coating processes and shipping. This decentralized process inventory was challenging to control, very labor-intensive to manage and led to quality-associated costs.

All PE-coated rolls had to be fully wrapped twice: once in order to tolerate the maneuvering by clamp trucks in the intermediate storage process and again after the PE coating before being shipped to the customer.

Storage tightly integrated into mill processes:

• Intermediate storage for production
• Shipment buffers for finished rolls
• Simplified, more efficient internal logistics

With the automated roll warehouse, the target was to integrate a sufficient intermediate roll buffer in the mill area between the production, converting and shipping processes, and to cut costs by simplifying and automating the internal logistics.

Delivering improved logistics efficiency

The TransRoll™ automated high bay storage at Stora Enso is an ideal example of Pesmel’s Material Flow How® concept, representing the perfect union between storage and production. This automated storage operates both as an intermediate buffer for rolls going to PE extrusion coating, and also as a shipping roll buffer for finished customer rolls. The volume was defined as being around 30 000 tons, with a wide range of roll dimensions and weights.

When comparing different type of automated warehouse concepts, it is very important to analyze the total cost of ownership of each alternative. This means the CapEx and OpEx costs related to the warehouse concept itself but also the costs of the systems and structures needed to integrate it into the mill operations. This means the ability to integrate the automated warehouse into the center of the production process with a minimal number of conveyors, and the civil engineering to feed the roll flow in and then to distribute it for converting and shipping.

Here, system suppliers like Pesmel, who can offer the full scope, including the conveyor system and all storage concepts, have the upper hand over part suppliers who concentrate only on their own core area. This advantage was obvious in the Stora Enso Imatra case where the automated storage was integrated with the production operations around it by eight automated connections at different floor levels, in a very limited amount of space.

Comparison of features between TransRoll™ high bay storage and traditional overhead crane warehousing

	TransRoll	Overhead crane warehouse
Use of space/storage density	Footprint 1/3	Footprint 3/3
Handling capacity	400 rolls per hour	100 per hour
Simultaneous handling of different roll sizes	Yes	Not possible
Conveyor systems and storage connections	Simple conveyor systems, Connects to the warehouse from wherever needed	Extensive conveyor systems, Complicated to connect
Handling quality	Horizontal handling, no clamp handling	Lots of clamp handling
Safety (esp. fire safety)	Sprinklers in every roll channel Rolls lie in the channel, with no danger of tipping	Sprinklers on store ceiling Rolls are stacked, creating a tipping risk

A smart and simple solution

Project Manager Tommi Myller, from Stora Enso Imatra mills says, “This new automated roll storage simplified our internal logistics a lot. Now we only need one operator to control the process of buffering and sorting the production between paper machines, PE coating and shipping. This is a huge advantage over the previous decentralized operations, with multiple clamp truck drivers and supervisors to manage and handle the intermediate inventory.”

“This new automated roll storage simplified our internal logistics a lot.”

Tommi Myller, Project Manager, Stora Enso

For Stora Enso, where this new central distribution buffer required eight connection points, the TransRoll™ high bay storage concept was much simpler and less space-consuming to implement than any alternative method. An additional benefit is that it can be easily expanded in the future. If needed the rack can simply be extended without disturbing the ongoing production process.