Materiaalihukan määrän ja syiden selvittäminen MammuttiHirren tehtaalla

Abstract

Opinnäytetyössä selvitettiin hirren valmistuksessa syntyvä työvaihekohtaisen materiaalihukan määrä.

The loss of material is an indicator that describes the effectiveness ofthe production process. Until now the loss has not been observed very accurately at MammuttiHirsi, which manufactures laminated logs. Especially the loss at each stage of process was not known clearly. The existing knowledge on the loss of material at each stage has basically been acquired through experience.

ln this study the amount of lost material at each phase of log production process has been investigated. The purpose of this study was also to find out the factors that cause material loss and come up with improvement suggestions through which the loss could be reduced. Only those phases in which the loss was remarkable were studied closely. The loss was classified and analyzed in the respect of sawmills, timber products, timber species and different logs.

The study began by becoming acquainted with the phases of log production. After that the necessary information was collected. The information was collected with both existing and new monitoring forms prepared for this study. After the information was collected, the correctness and the representativeness of the data were scrutinized. At first there were some problems with the correctness of data due to entry faults made by the employees at the production. These problems are described in more detail in the analysis ofthe results.

According to this study the loss of material was greatest during quality control as well as when planks were joined and timberwork made. Because of the lack of reliability of the monitored data it was not possible to count loss percents in the respect of sawmills, timber products, timber species and logs. However, new information was gained extensively on the reasons that cause loss as well as their proportional meanings in the process. The results indicate that cracks were the main reason för the loss of materia! and decrease in the quality in first-rate timber products. In the lower-rate timber products the effects of cracks were not so remarkable. Because of that the first-rate timber products with cracks should be used in places where lowerrate timber products are used in order to reduce loss of material.

During timberwork the loss was mainly caused by the short groove of log balk and other faults resulting from adjusting draft, design error, scoring error, mechanical damage, optimization error and double-made logs. The results of this study also indicate that the residual bit of log, in other words, the loss of optimization deviated from the reality. It was also found out that the most part ofthe faults observed during timberwork were created at an earlier stage ofthe production.