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Rätt från skogsbruket: En fallstudie enligt DMAIC vid Sveaskog
2014 (Swedish)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The forest industry is under great stress to deliver products to competitive prices. For this to be possible, a strong forestry that can deliver raw materials, meeting the increasing expectations of the customers regarding timber and pulp wood, is needed. Sawmills are exposed to global competition which forces them to continuously adapt and make their production more efficient which in turn increases their demand on the forestry sector. Today the forestry doesn't fulfill the demands on specific timber lengths from the customers due to issues regarding variation. An effective way to address variation problems is to use DMAIC, a structured problem solving methodology. DMAIC is an acronym for Define, Measure, Improve, Analyze and Control. Each step of the method is based on the result from the previous step aiming to identify and rectify root causes for a specified problem. Variation in the harvesting process causes problems for the customers, particularly if the delivered logs are too short. A company that is experiencing problems with variation in their harvesting process is Sveaskog. About 9-10 percent of the delivered logs to their customer Jutos Timber in Norrbotten were shorter than requested. When a log is to short it is downgraded to the underlying module length which often implies a lower price per timber volume, hence causing a loss of revenue for Sveaskog. In total, Sveaskog in Northern Norrbotten could save 890 000 SEK annually just by securing that the delivered logs satisfies the length requirements. It is also important to simultaneously reduce the standard deviation for each harvesting team so that Sveaskog in a more predictable way can ensure that their harvesting process continuously will deliver logs above the lower specified tolerance limits.At the step Analyze a significant difference between the harvesting teams in the Northern Norrbotten where depicted. Teams with a lesser performance were showing greater sensitivity to changes in temperature or shifts in harvesting areas amongst other similar factors. This led to a further investigation to identify features making certain teams more robust against these changes. An interview study showed that the measuring wheel as well as the calibration procedure differed between teams, a pattern that was found to have correlation with the overall robustness of their harvesting process. In addition, the relation between the size of the cutting window and the standard deviation of the length was investigated. Also, using statistical calculations, a way to shift the center of the harvesting process to effectively decrease the percentage of short logs delivered was developed.These factors were then tested on different harvesting teams to investigate their effects on the standard deviation. The result of the study showed that a double measuring wheel with overlapping teeth produced the lowest standard deviation. Furthermore, it was possible to reduce the proportion of logs that are too short with use of the developed center calculation formula. The study also showed that the width of the cutting window is possible to reduce to 1 centimeter, but the general recommendation to Sveaskog is to reduce the cutting window to 2 centimeters. In addition, a recommendation of a new calibration routine for Sveaskog was developed through a survey study. In conclusion, the study has successfully illustrated how the problem-solving methodology DMAIC can be used to address and rectify problems with variation within the forestry sector.

Place, publisher, year, edition, pages
2014. , 101 p.
Keyword [en]
Keyword [sv]
Teknik, DMAIC, skogsbruk, avverkningsprocess, arviation, robusthet, timmer, stocklängd
URN: urn:nbn:se:ltu:diva-49699Local ID: 703c8f0b-6dc6-441d-b66f-cfbb64e8e1cbOAI: diva2:1023046
External cooperation
Subject / course
Student thesis, at least 30 credits
Educational program
Industrial and Management Engineering, master's level
Validerat; 20140623 (global_studentproject_submitter)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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Holmgren, JakobTidblad, Sofia

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