Change search
ReferencesLink to record
Permanent link

Direct link
The Effect of Log Position Accuracy on the Volume Yield in Sawmilling of Tropical Hardwood
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
Number of Authors: 4
2016 (English)In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, no 4, 9560-9571 p.Article in journal (Refereed) Published
Abstract [en]

This study investigated the effect of the positioning of the log before sawing on the volume yield of sawn timber from tropical hardwood species. Three positioning parameters were studied, the offset, skew, and rotation, combined with two sawing patterns of cant-sawing and through-and-through sawing. A database consisting of two tropical hardwood species with very different outer shapes, jambirre (Millettia stuhllmannii Taub.) and umbila (Pterocarpus angolensis DC.), was used to simulate the sawing process. The result of the simulation revealed that, according to the combined effect of offset, skew, and rotation positioning, the positioning of the log before sawing is extremely important to achieve a high volume yield of sawn timber. The positioning parameter that has the highest effect on the volume yield is the rotation, and the variation in the volume yield associated with a deviation in the positioning can reduce the volume yield of sawn timber by between 7.7% and 12.5%.

Place, publisher, year, edition, pages
2016. Vol. 11, no 4, 9560-9571 p.
Keyword [en]
Log positioning error; Tropical species; Skew; Offset; Rotation
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
URN: urn:nbn:se:ltu:diva-37010DOI: 10.15376/biores.11.4.9560-9571OAI: oai:DiVA.org:ltu-37010DiVA: diva2:1012405
Note

Validerad; 2016; Nivå 2; 2016-11-23 (andbra)

Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2016-11-30Bibliographically approved
In thesis
1. SAWING STRATEGIES FOR TROPICAL HARDWOOD SPECIES: Simulation studies based on industrial conditions of Mozambique
Open this publication in new window or tab >>SAWING STRATEGIES FOR TROPICAL HARDWOOD SPECIES: Simulation studies based on industrial conditions of Mozambique
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The harvesting of Mozambique tropical hardwood species is considerable higher than the natural regrowth in the forest and the stock is decreasing drastically. Therefore, it is important to improve the material recovery when the wood is refined (i.e., in sawing and further refinement to products such as joineries, furniture etc.) to reduce the waste and to re-utilize efficiently the by-products to increase the added value. The wood processing industry is an important means to boost the industries in the rural areas and also to generate incomes for the local communities by creating jobs and business opportunities.

The majority of the logging that can be used for sawmilling in Mozambique is exported as roundwood due to the inability of companies to meet the product standards set for export and to generate profit. The lack of capabilities of the local sawmills to generate profit, also foments the illegal logging because of the higher price of roundwood for export which contributes to increase the number of unlicensed individuals in harvesting. This threatens the law enforcement and thus the degradation of the local wood industry. An alternative to increase the profit and empower the local community could be to export more refined wood products such as sawn timber, parquet, and veneer instead of the roundwood.

The objective of the work was to investigate alternative sawing strategies of tropical hardwood species that could increase the profitability of the Mozambique wood industry in general and at sawmill in particular. The subject was approached using a database of virtual logs and together with a sawing simulator. The thesis has two main focus areas: (1) creating the log database with the corresponding algorithms for sawing simulation, and (2) investigations of alternative sawing strategies.

The first focus was to build the database of surface-scanned logs and develop the algorithm for the saw simulation. The results are a database of 15 logs models describing the logs outer shape in which 10 jambirre (Millettia stuhlmannii Taub.) and 5 umbila (Pterocarpus angolensis DC.), and the algorithm for the sawing simulation. The algorithm use “brute force” i.e., determines all volume yields of sawn timber from the combination of all settings of log-positioning parameters (offset, skew and rotation) and selects the maximum value of volume yield. From simulation, using three sawing patterns (cant-sawing, through-and-through sawing and square-sawing) combined with two positioning parameters (offset and rotation) it was found that the sawing pattern has great impact on volume yield and that the square-sawing gave higher yield followed by through-and-through sawing pattern.

The second focus was on alternative sawing strategies; having in mind that the optimal volume yield is achieved by aid of computerized production systems and that these resources are not yet in use in Mozambique. Hence, the objective was to find the positioning parameters that can be set manually and improve the volume yield. The result have shown that the rotation is the most affecting parameter followed by offset and skew, and that the volume yield can decrease by between 7.7% and 12.5% from the optimal positioning when the logs are manually positioned with the knowledge about the optimal log position. In another study, using crook-up or horns-down positioning as alternative to the optimal positioning, the volume yield decreases by between 10% and 13% from the optimal positioning. By using bucked logs , the optimal volume yield increased by between 8% and 13% in relation to full lengths logs, and the volume yield of bucked logs when using crook up positioning decreases 2% in relation to optimal positioning of full length logs.

It is concluded that there is an unexploited value potential in the wood chain which can be reached using alternative positioning and modern measurement techniques and that the grading of wood will facilitate and improve the sawing process.

Place, publisher, year, edition, pages
Luleå University of Technology, 2016
Keyword
sawing strategies, tropical hardwood species, simulation, volume yield, log grading, umbila, jambirre.
National Category
Engineering and Technology
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-38902 (URN)978-91-7583-717-8 (ISBN)978-91-7583-718-5 (pdf) (ISBN)
Public defence
2016-12-02, Hörsal A193, Forskargatan N 1, Skelleftea, 10:00 (English)
Opponent
Supervisors
Available from: 2016-10-12 Created: 2016-10-03 Last updated: 2016-11-16Bibliographically approved

Open Access in DiVA

fulltext(1241 kB)6 downloads
File information
File name FULLTEXT01.pdfFile size 1241 kBChecksum SHA-512
219c4b163cf7f65ee22dfa17bca39c93fc9aed5978ae97859e60887b5316dc338bc359d5a679f5830149b2a50fc0795b776890cbc9e6d873d1e334d323c83b1d
Type fulltextMimetype application/pdf

Other links

Publisher's full texthttps://www.ncsu.edu/bioresources/BioRes_11/BioRes_11_4_9560_Shenga_BBS_Effect_Log_Position_Accuracy_Vol_Yield_Sawmilling_10000.pdf

Search in DiVA

By author/editor
Ah Shenga, PedroBomark, PeterBroman, OlofSanberg, Dick
By organisation
Wood Science and Engineering
In the same journal
BioResources
Other Mechanical Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 6 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 44 hits
ReferencesLink to record
Permanent link

Direct link