Articles containing the keyword 'log size'

A model was developed in order to describe the peeling of veneer for determining value relationship for birch veneer logs and stems. The model was based on selling prices of veneer and other products as well as processing costs. The model was utilized for determining the effect of various input variables on the log value.

According to the results, the effect of tree size was important for the value of raw material. Even knottiness had an effect although only in the higher manufacturing costs of knotty veneer were taken into account. Pruning was a method to increase substantially the proportion of knotless veneer.

The PDF includes an abstract in English.

• Kärkkäinen, E-mail: mk@mm.unknown

In order to evaluate the strength properties of boards made from small and large Norway spruce (Picea abies) butt logs, 15 small (top end diameter 13 cm) and 15 large (top end diameter 25 cm) logs were sampled from a sawmill in Finland. From each log two test pieces were made in order to measure the bending and compression strength, dry density and average ring width.

The boards from small logs were stronger and their density higher. When the differences between groups were analysed it was found that the strength was determined by the density and ring width. When the density was kept constant, the increase in ring width had a decreasing effect on the strength properties. Because there was a negative correlation between ring width and density, ring width alone had a great effect on the strength properties.

The PDF includes a summary in English.

• Kärkkäinen, E-mail: mk@mm.unknown
• Hakala, E-mail: hh@mm.unknown

The aim of the study was to explain the regression between the cubic content of the trunk of a tree and of logs cut from the trunk. The minimum size of trunk that can be used to saw logs has been 18 feet long and 5″ of top diameter in Finland (in 1930s). The average length of logs is 16‒18 feet. The data of this study was collected in seven areas around Finland. The results show that there is regression between the volume of the trunk, the volume and the logs cut from the trunk and the number of logs. Consequently, it is possible to determine the average regression between the trunk and log sizes for forest technical purposes. The regression varies in different parts of the country due to varying growth condition of the trees and different age classes. It is probable that the figures have to be re-examined in the future.

The PDF includes a summary in English.

• Vuoristo, E-mail: iv@mm.unknown

The influence of log properties (diameter, length, taper, volume, density and quality), sawing pattern, yield, sawing efficacy, stoppages, consumption of electric power and thereby on the financial result of sawing was examined. In addition, the significance of various revenues and costs were studied from the point of view of the financial result of sawing. The revenues from sawing are composed of revenues obtained from sawn goods, chips, sawdust and bark. The costs in sawing are made of raw material, capital, labour, energy and other costs. The results were calculated per diameter class and applying the basic principle of targeting all returns and costs on the different diameter classes.

The results are based on test sawings of a total of 1,606 Scots pine logs representing eight diameter classes,  using conventional frame saw sawing patterns. In addition, a sawing simulator was used. Log top diameter had a significant influence on the financial result obtained when calculations were made per log volume. The financial result obtained for the biggest diameter class exceeded that of the smallest diameter class by FIM 99.1/m³. Sawing revenues accounted for FIM 66.0/m³ and sawing costs for FIM 33.1/m³ of this difference. In addition to being influenced by the top diameter, the yield and sawing efficacy were observed to have a clear influence on the financial result. The influence of stoppages was smaller.

The only means of gaining significant improvement in the annual result obtained from sawing were improvements in the revenues from sawn goods or reductions in the cost of raw material. Increase of the minimum diameter led to a significant improvement in the annual result obtainable from sawing only if the production time remained unchanged; i.e., when correspondingly more logs from the other diameter classes were sawn. If the production time was reduced by an amount corresponding to the increase in minimum diameter, then the annual result fell dramatically except in the case of minimum diameter.

The PDF includes a summary in English.

• Hakala, E-mail: hh@mm.unknown