Imaging technologies as an enabler of a modern sawmill

Imaging technologies as an enabler of a modern sawmill


The development of technology has shaped the world to a great extent over the decades, and the sawmill industry has not missed out on this development. Modern technology brings sawmill operators new opportunities, e.g. in terms of traceability, production planning and quality optimization.

A good example of things that modern technology is enabling is the traceability of sawn timber pieces all the way to the place where the log comes from. X-ray imaging of logs, which is also in use at all Pölkky sawmills, enables the so-called fingerprint traceability, where the log’s internal properties, e.g. the location and quality of the branches are unique to each log, and based on that it is possible to identify in a later stage of the sawing process, from which harvest area the raw material of the piece of timber in question comes from. On the other hand, the same technology can also be used to look at the grading per harvest area, i.e. what quality logs were in the batch sold by the forest owner.

X-ray imaging essential in production planning

In the planning of a modern-day saw production, technology plays a significant role in every step of the sawing process. When planning what to saw from the available material, modern technology together with programmatic planning enables maximizing the value that we get out of each log. Production planning combines forecasts from both sales and procurement to create an offering that best serves customer needs and company objectives.

To get the maximum value out of every log, sorting and X-ray scanning the logs plays a vital role already before the actual sawing. Based on the X-ray imaging and what kind of products are needed, the logs are sorted to different bins. In log sorting we choose which logs are suitable for each product. Log data can be used to perform simulations and optimize the end result, e.g. by combining the needs of sales with the available raw material.

Log’s internal features – which can be seen with the X-ray imaging – determine what kind of use the wood is best suited to. Logs typically have knots that affect the visual appearance and structural strength of the product. When the visual look of the final product is critical, for example in panels, the preferred material does not have branches or defects that are not allowed in the final products or that impair their visual quality. On the other hand, there are many products that are not used in such visible places, e.g. structural elements inside walls, where visual aspects are not that critical, but they still are stable and fulfill strength requirements. Logs are often sorted according to the type of branches, for example the butt logs with small branches are suitable for window and door components and molding products, while top logs with large healthy branches are suitable for furniture industry and interior cladding panels. Middle logs, on the other hand, are often used in the log house industry.

<p”>Other features one might look into are the share of heartwood, as discussed in our earlier blog article, thickness of the growth rings, if the knots are alive or not, and the distance between knot clusters. When producing e.g. raw material for knotless window and door frames, wood with long distance between knot clusters would be chosen.

Basically, when the log goes into the sawing process, we want it to be sawn from the beginning as much as possible according to the plan and the customer’s needs. Pölkky uses very modern Finnos X-ray measurement frames at all our mills. This could be seen as a new era in the sawmilling business, as we can look inside the log before starting the production process. Looking just 20 years back, it was a guessing game as decisions on sorting were made based on looking solely at the surface of the log, its slope and curve, the thickness of the bark, how bumpy it is, etc. As a result of this reasoning, only about 70% of the sawed products corresponded to the planned, which caused almost a third of the production not reaching the desired quality level, or they needed further processing to be usable for some other purpose. Now with the modern technology a much higher accuracy can be reached, which leads to consistent quality.

Technology helps in optimizing the end result

Each log yields many different products; the center cut, sideboards and by-products. The aim is to maximize the amount of center cut, as it’s the most valuable part of the log. In addition, the side boards are sawn from the surface of the log. The size and dimensions of these timber products are optimized by software calculations in order to produce as much valuable timber as possible, which meets the demand. In addition to getting a high share of wood products out of each log, nothing goes to waste at Pölkky’s production. By-products are created during sawing and processing, such as bark, sawdust, wood chips and shavings, which are further processed into various products, either by Pölkky or our partners.

The technology used at the sawmill affects optimization in great detail. The modern technologies can optimize e.g. the infeeding of the log to the sawing process. As the log is never a perfect circle in diameter or completely straight, the saw line needs to decide how to infeed the log, how to turn it to make the maximum yield out of it. The new investments Pölkky is currently implementing in Taivalkoski and Kajaani, for example, involve the newest technology that help in making decisions about feeding the log into the saw line with the best possible accuracy.

After sawing, the products go to green sorting. The pieces go through a grading station where camera technology is again used. The pieces are sorted according to their intended use, as they are kilned in the next stage to their desired moisture level.

Advanced technology included in every step of the process

Pölkky’s modern technology yields high-quality sawn timber without production defects that might affect possible further uses. After this stage, some of the products are used as sawn timber and some continue for further processing, where planing and other processing phases will change the look of the product to a great extent. Nevertheless, getting the first phases right creates many opportunities to further processing.

Only recent data analytics solutions, combined with modern cloud services, have made it possible to process a large amount of data, which has enabled the introduction of production optimization software at sawmills. Modern technology therefore plays a central role in every step of the sawing process. For each log, we want to find the optimal purpose of use according to customer needs, in accordance with the logs’ individual characteristics.

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