After felling, the roundwood is stored in the forest for a while before the transportation. Storage period should be shortest possible, in order to avoid the deterioration of the raw material. Also high stocks of logs tie down unnecessarily company’s working capital.
Logistics for sawn log
Usually, the logistics for sawn logs is planned in such a way that the transportation to the mill follows immediately after the felling. Seasonal factors forces the stocks to be increased – this applies especially to periods before the frost and then again when the thaw comes.
Sometimes, there are even intermediate cold storage areas to ensure the log supply, but the mill stocks are kept low for instance due to lack of space. Energy wood is stored for longer periods, because this also dries it out.
© Versowood Oy/Osmo Puuperä
Especially, when logs are transported by rail the timing is crucial in both ends, as there is less flexibility compared with lorry transportation.
Transportation plans are the responsibility of the log sourcing organization or the transport operator. These plans can be adjusted as the felling operation progresses.
Log storage at the mill
Key factors affecting log storage volume needs are the turnover time of log stock and seasonal variations in demand of sawn goods and supply of logs. Sawn logs, which define much of the timing in logging operations and transportation, do not have usually any need for longterm storage. The turnover of sawn logs stocks is well over 20 times per year.
Especially in spring and summer, if sawn logs are stored for longer periods of time there is a danger for a rapid quality deterioration for instance with insect damage and blue stain. At sawmills the logs are sprayed in spring and summer to avoid that type of damage.
However, a long-term spraying may cause long-term permeability damage to the fibre, which could be shown as darker patches in stained wooden end products. Tannin in the bark may also colour the surface of the logs darker. This does not have much effect on sawn logs, because those darker sections are usually going to be chipped in the sawing process.
Conifer sawn logs cannot be stored in water for long. The maximum safe period for redwood logs is four weeks and whitewood six weeks, when the water temperature is +15 ˚C. Longer storage may result in permeability damage. Furthermore, there can be issues in the actual process with loose bark coming off the logs, blocking conveyors and photovoltaic devices.
With the water storage one must ensure that the logs or their parts above the water will not dry and become exposed, resulting in drying or blue stain. Because of the reasons above the log storage in water is these days rare.
Storage data
The storage data needs to be accurate in order to ensure successful logistic steering of goods. As stated before the log data can be transferred during the logging process automatically from the site. After the logged goods have been transported to the roadside there can be a production report produced.
There are also other methods to estimate the stocks, down to just assessing the volumes visually.
When the actual transportation from the forest takes place, the haulier needs to have following details:
- Batch details (contract number, forest owner, etc.)
- Storage place details
- Specie, length, volume
- Measuring type
- Place and time of delivery
LogForce
There is a commercial service called LogForce, through which the transportation company can plan its operations.
Principle:
- Forest companies send to LogForce transportation orders, including the load and storage details.
- Transportation companies have a real time information, including possible changes in available stocks after delivered loads.
Those forest companies, which do not use LogForce, may give the hauliers an access to their stocks through the IT system. These details can also be delivered by other means.
As stated above, there may be seasonal hindrances for lorries like in late Spring, when the frost thaws. Transportation conditions have to be anticipated well in advance and checked when needed.
Reception measurement
As a norm, all logs delivered to sawmills are measured piece by piece at the log sorter. This measuring gives also useful data about the sizes, lengths, top diameters and qualities.
In practice information from this point is handy for a multitude of uses: not only does one get exact details of purchased and delivered logs, this information can also be used for control purposes. Data from this point is also used for the production planning.
Current measuring systems make it possible to have a quality-based pricing, because each and every log can graded at this point thoroughly
