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Myronycheva, O., Karlsson, O., Sehlstedt-Persson, M., Öhman, M. & Sandberg, D. (2018). Distribution of low-molecular lipophilic extractives beneath the surface of air- and kiln-dried Scots pine sapwood boards. PLoS ONE, 13(10), Article ID e0204212.
Open this publication in new window or tab >>Distribution of low-molecular lipophilic extractives beneath the surface of air- and kiln-dried Scots pine sapwood boards
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2018 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, no 10, article id e0204212Article in journal (Refereed) Published
Abstract [en]

During industrial wood drying, extractives migrate towards the wood surfaces and make the material more susceptible to photo/biodegradation. The present work provides information about the distribution, quantity and nature of lipophilic substances beneath the surface in air- and kiln-dried Scots pine (Pinus sylvestris L.) sapwood boards. Samples were taken from knot-free sapwood surfaces and the composition of lipophilic extractives, phenols and low-molecular fatty/resin acids layers at different nominal depths below the surface was studied gravimetrically, by UV-spectrometry and by gas chromatography-mass spectrometry (GC-MS). The concentration of total extractives was significantly higher in kiln-dried than in air-dried samples and was higher close to the surface than in the layers beneath. The scatter in the values for the lipophilic extractives was high in both drying types, being highest for linoleic acid and slightly lower for palmitic, oleic and stearic acids. The amount of fatty acids was low in kiln-dried boards, probably due to a stronger degradation due to the high temperature employed. The most abundant resin acid was dehydroabietic acid followed by pimaric, isopimaric, and abietic acids in both drying types. It is concluded that during kiln-drying a migration front is created at a depth of 0.25 mm with a thickness of about 0.5 mm.

Place, publisher, year, edition, pages
PLOS, 2018
National Category
Wood Science Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-71200 (URN)10.1371/journal.pone.0204212 (DOI)000446921100033 ()30303988 (PubMedID)2-s2.0-85054716404 (Scopus ID)
Projects
Experimental studies of capillary phenomena in bio-based materialsFungal growth on modified wood-based products under subarctic conditionsModWoodLifeUnderstanding wood modification through an integrated scientific and environmental impact approach
Funder
Swedish Research Council
Note

Validerad;2018;Nivå 2;2018-10-29 (svasva)

Available from: 2018-10-13 Created: 2018-10-13 Last updated: 2019-06-14Bibliographically approved
Karlsson, O., Myronycheva, O., Sehlstedt-Persson, M., Öhman, M. & Sandberg, D. (2017). Multivariate modeling of mould growth in relation to extractives in dried Scots pine sapwood. In: Proceedings IRG Annual Meetin: . Paper presented at 48th Conference of the International Research Group on Wood Protection, IRG48, Ghent, Belgium, 4-8 Jun 2017. , Article ID 17-20629.
Open this publication in new window or tab >>Multivariate modeling of mould growth in relation to extractives in dried Scots pine sapwood
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2017 (English)In: Proceedings IRG Annual Meetin, 2017, article id 17-20629Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

Influence of extractives on mould growth on Scots pine sapwood dried in air or in kiln was studied. Boards were sprayed with water mixtures of spores of the fungal species Penicillium sp., Aspergillus sp., Mucor sp., Paecilomyces sp., Trichoderma sp., treated at a temperature of 22ºC at 90% RH, classified into a percentage of covered area. Acetone and water extracts were isolated and analyzed for sugars, nitrogen, ash, resin/fatty acids, glycerol, and phenols. A multivariate Orthogonal Partial Least Squares (OPLS) regression model was developed to study relations between the extent of mould coverage of boards and chemical content. The model describes 51% variability in X and 69% in Y with prediction power of 55%. The results indicated that total acetone soluble extractives and sugars like glucose contributed to increased mould growth whereas fatty acids prevent mould growth.

Keywords
Multivariate analysis, sapwood, fungi
National Category
Materials Engineering Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-63985 (URN)
Conference
48th Conference of the International Research Group on Wood Protection, IRG48, Ghent, Belgium, 4-8 Jun 2017
Available from: 2017-06-14 Created: 2017-06-14 Last updated: 2019-06-14Bibliographically approved
Ekevad, M., Berg, S., Öhman, M. & Guo, X. (2017). Potential Yield Increase with Reduced Saw Kerf Deviations when Curve Sawing. In: : . Paper presented at 23rd International Wood Machining Seminar (IWMS-23), Warsaw, Poland, May 28-31, 2017.
Open this publication in new window or tab >>Potential Yield Increase with Reduced Saw Kerf Deviations when Curve Sawing
2017 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Curve sawing with circular saw blades introduces saw kerf deviations due to the combination of the flat sawblade and the curvature of the saw kerf in log or cant direction. Deviations for a double arbor resaw used for curve sawing, are that the saw kerf becomes wider at top and bottom and that the desired rectangular cross sections of the boards become distorted. The yield loss due to the saw kerf deviation in practice for a sawmill was of interest in this study. Earlier and very approximate guesses and simple estimates have been indicating that the loss of income for a sawmill in Sweden producing 200’ m3 of sawn timber may be about 2 MSEK/year (0.22 Meuro/year). In this study calculations were based on true log data and assumed sawing conditions for a sawmill. A true mixed input log assortment (78458 spruce and pine logs taken into the log yard of a sawmill in northern part of Sweden) was used as basis. Individual curvature of these logs was taken into consideration but the calculation was still approximate because not all facts about sawing patterns, log classes etc. for an actual sawmill were known. Instead one single sawing class was used for the calculation of saw kerf deviation.

 

Results show that the direct yield loss given the assumed input data was 0.61 %-units. This corresponds roughly to the income loss 0.2 Meuro/year mentioned above. Besides from the yield increase there are other advantages gained if the saw kerf deviation can be reduced.

Keywords
Curve sawing, ripsawing, saw kerf deviation, sawing yield, sawmill
National Category
Engineering and Technology Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-63068 (URN)
Conference
23rd International Wood Machining Seminar (IWMS-23), Warsaw, Poland, May 28-31, 2017
Available from: 2017-04-19 Created: 2017-04-19 Last updated: 2017-11-24Bibliographically approved
Ekevad, M., Guo, X., Li, R. & Öhman, M. (2016). Curve sawing effects on board dimensions when rip-sawing with a circular saw blade (ed.). Wood Material Science & Engineering, 11(3), 135-141
Open this publication in new window or tab >>Curve sawing effects on board dimensions when rip-sawing with a circular saw blade
2016 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 11, no 3, p. 135-141Article in journal (Refereed) Published
Abstract [en]

Curve sawing means advantages for yield and quality of sawn boards. However, for circular saw machinery deviations of saw kerfs give losses of valuable board volume. Deviations give thinner boards but also slight cupping of the cross sections. Theoretical calculations show that even with moderate (large) curve radii, these saw kerf deviations are typically 0.2–0.6 mm for normal circular saw machinery and Swedish log material. The test sawing reported here was made in order to give experimental values that can be compared to theoretical values. Fifty normal logs and 50 curved with top diameter 236–248 mm were cut with sawing pattern 3X with center boards 51 × 149 mm. The average curve radius of the curved cants that were cut in the resaw was 132 m (bow height 19 mm) and the theoretical saw kerf deviation for this radius is 0.31 mm. The experimental results show that the thickness reduction at the measuring points for curve sawn boards compared to straight sawn boards was in average 0.19 mm to be compared with the theoretical value of 0.20 mm. Cupping was more difficult to measure but results seem to agree well between theory and experiments.

National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-31222 (URN)10.1080/17480272.2016.1150342 (DOI)000375935000003 ()2-s2.0-84961218673 (Scopus ID)55774805-e94c-4e3e-b19f-bbb674543cdb (Local ID)55774805-e94c-4e3e-b19f-bbb674543cdb (Archive number)55774805-e94c-4e3e-b19f-bbb674543cdb (OAI)
Note

Validerad; 2016; Nivå 1; 20160510 (andbra); Konferensartikel i tidskrift

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-07-10Bibliographically approved
Sehlstedt-Persson, M., Öhman, M., Marklund, B. & Myronycheva, O. (2016). Hyveldjupets inverkan på mögelbenägenhet hos råspont av furu och gran (ed.). Paper presented at . Skellefteå: TräCentrum Norr
Open this publication in new window or tab >>Hyveldjupets inverkan på mögelbenägenhet hos råspont av furu och gran
2016 (Swedish)Report (Other academic)
Abstract [sv]

Råspont av furu och granbrädor hyvlas av splintvedsrika sidbrädor. Råvaran till råspont postad som sidutbyte har ett rikt innehåll av kolhydrater i splintveden, speciellt i vinteravverkat timmer där furusplint normalt har högre näringsinnehåll än gransplint. Risken för mögelangrepp på råspont är stor om det omgivande klimatet är gynnsamt för mögeltillväxt - ett tilltagande problem i och med ett allt fuktigare och varmare klimat. Hög luftfuktighet i kombination med näring som anrikats mot virkesytorna under forcerad virkestorkning kan snabbt leda till missprydande mögelangrepp på råspont som används i t.ex. underspikning av takfot, takluckors insida i ouppvärmda vindar i småhus, väggar i carport mm. Tidigare studier har visat att det är fullt möjligt att styra näringsvandringen i till en utvald sida av brädorna under torkningsprocessen genom dubbelläggning av brädor och att därefter hyvla bort dessa ytor. I praktiken är detta dock svårt att industrialisera då dubbelläggning av brädor vid sågverken är slumpvis vad gäller vilka sidor som läggs ihop i kombination med att brädorna vanligen har olika längder.Numera bearbetas oftast alla ytor av råspont jämfört med tidigare där begreppet ”rå” innebar att en flatsida lämnades obearbetad. Denna flatsida profilhyvlas med ett finprofilerat vågformat rillstål på märgsidan dvs. den brädsida som inte har vankant. Projektets syfte har varit att undersöka ifall det rilldjup som idag används är tillräckligt för att avlägsna den näringsanrikade veden för att undvika mögelpåväxt i långtidsanvändning. I studien har torkade, dubbellagda 22x100 mm furu och gran brädor som hyvlats med ett hyveldjup mellan 0 – 1,9 mm, jämförts i ett forcerat, korttids mögeltest. Resultaten av detta mögeltest med mögelarterna Penicillium sp. Paecilomyces sp. och Rhyzopus sp., som använts vid indirekt kontaminering av försökmaterialet visar följande•En tydlig trend kan ses för furu med avtagande mögelgrad vid ökande hyveldjup. För att ytorna ska klassas som bra-acceptabla i praktiskt bruk bör inte mögelgraden överstiga mögelgrad 2. Enligt resultat i denna studie bör därför hyveldjupet för furu vara minst 1,5 mm. •För gran är resultaten inte lika entydiga men även här verkar ett hyveldjup på minst 1,5 mm vara lämpligt. Träslagens mögelbenägenhet är vid detta hyveldjup ungefär likvärdig. •Om hyveldjupet är mindre än 1,5 mm är furu betydligt mer mögelbenägen än gran och risken stor att splinten angrips av mögel. •Vid rillhyvling bör därför rillans ”toppar” ligga 1,5 mm in i virket.

Place, publisher, year, edition, pages
Skellefteå: TräCentrum Norr, 2016. p. 22
Keywords
Forestry, agricultural sciences and landscape planning - Wood fibre and forest products, mögel råspont furu gran, Skogs- och jordbruksvetenskap samt landskapsplanering - Träfiber- och virkeslära
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-21861 (URN)07e4e534-d5bb-4033-b3b5-8b30022c8667 (Local ID)07e4e534-d5bb-4033-b3b5-8b30022c8667 (Archive number)07e4e534-d5bb-4033-b3b5-8b30022c8667 (OAI)
Note

Godkänd; 2016; 20160524 (marseh)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Öhman, M., Grubii, V., Sandberg, D. & Ekevad, M. (2016). Moistening of the wood surface before planing for improved surface quality (ed.). Paper presented at International Wood Machining Seminar : 14/06/2015 - 19/06/2015. Wood Material Science & Engineering, 11(3), 156-163
Open this publication in new window or tab >>Moistening of the wood surface before planing for improved surface quality
2016 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 11, no 3, p. 156-163Article in journal (Refereed) Published
Abstract [en]

The roughness of a machined wooden surface is affected by a number of factors such as cutting tool geometry, machine settings and wood structure. The influence of wood structure on wood surface quality is difficult to control since the surface roughness is dependent on the local combination of density, grain direction and moisture content (MC). The greater the variation in wood features, the more difficult it is to find a combination of tools and machine settings that will give a high surface quality. The purpose was to study the impact of a surface wetting treatment before planing in order to reduce torn grain in the wood surface near knots in sawn timber of low MC. The study was based on a total of 120 specimens of Scots pine (Pinus sylvestris L.). To maximize the variation in grain orientation and density, the specimens contained both clear wood and knots. The results showed that when the surface was moistened before planing, chipped and torn grain in areas of deviating grain close to knots decreased. The response to wetting was rapid, wetting less than 30 s before planing gave as good an improvement as treatment time of 30 min or more.

National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-30365 (URN)10.1080/17480272.2016.1166395 (DOI)000375935000006 ()2-s2.0-84962565503 (Scopus ID)4258f00d-47c8-4cf3-8d27-50ff1bb41cd5 (Local ID)4258f00d-47c8-4cf3-8d27-50ff1bb41cd5 (Archive number)4258f00d-47c8-4cf3-8d27-50ff1bb41cd5 (OAI)
Conference
International Wood Machining Seminar : 14/06/2015 - 19/06/2015
Note

Validerad;2016;Nivå 1;20160414 (andbra);Konferensartikel i tidskrift;Bibliografisk uppgift: Special Issue: International Wood Machining Seminar 2015

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-07-10Bibliographically approved
Grubii, V., Öhman, M. & Ekevad, M. (2015). Influence of Wetting on Surface Quality during Scots Pine Planing (ed.). In: (Ed.), : . Paper presented at International Wood Machining Seminar : 14/06/2015 - 19/06/2015.
Open this publication in new window or tab >>Influence of Wetting on Surface Quality during Scots Pine Planing
2015 (English)Conference paper, Oral presentation only (Refereed)
Keywords
Materials science - Surface engineering, wood planing moisture, Teknisk materialvetenskap - Ytbehandlingsteknik
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-39823 (URN)eb65c58b-9cef-4cb4-9e1d-8bcc3e73829f (Local ID)eb65c58b-9cef-4cb4-9e1d-8bcc3e73829f (Archive number)eb65c58b-9cef-4cb4-9e1d-8bcc3e73829f (OAI)
Conference
International Wood Machining Seminar : 14/06/2015 - 19/06/2015
Note

Godkänd; 2015; 20150625 (matse)

Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
Öhman, M., Ekevad, M. & Grubii, V. (2015). Remoistering of the wood before planing: a method for improved quality (ed.). In: (Ed.), Roger Hernández; Claudia B. Cáceres (Ed.), Proceedings of the 22nd International Wood Machining Seminar: . Paper presented at International Wood Machining Seminar : 14/06/2015 - 17/06/2015 (pp. 245-251). Quebec city, Kanada: Universite Laval, Article ID 5.
Open this publication in new window or tab >>Remoistering of the wood before planing: a method for improved quality
2015 (English)In: Proceedings of the 22nd International Wood Machining Seminar / [ed] Roger Hernández; Claudia B. Cáceres, Quebec city, Kanada: Universite Laval , 2015, p. 245-251, article id 5Conference paper, Published paper (Refereed)
Abstract [en]

It is beneficial if the machining of wooden products is done at a moisture content equal to the climate the product is meant to be used in. For indoor products in central heated houses such moisture content is about 5-10%. For planing this is often a too low moisture content showing an increased risk of poor surface quality due to severe torn grain. Contrary to this too high moisture content will result in a fuzzy grain surface and problems with swelling and shrinkage of the product. The roughness of a machined wooden surface is affected by a number of different parameters like cutting tool geometry, machine settings and wood structure. The latter is the hardest to control since the surface quality is a result of the local combination of density, grain direction and moisture content. The larger the variation in wood features the more difficult it is to find a combination of tools and machine settings that will give a high surface quality.This study showed that by wetting the surface before machining, in this case planing, the average surface quality could be increased. No time dependences could be shown, wetting short before planing did show as good improvements as wetting treatment for 30 minutes or more.The study was based on a total of 120 test surfaces of Scots pine (Pinus silvestris L.). In order to maximize the variation in grain angle and density variations the test surfaces contained both clear wood as well as green knots.

Place, publisher, year, edition, pages
Quebec city, Kanada: Universite Laval, 2015
Keywords
Industrial engineering and economy - Other industrial engineering and economics, planing, wood, surface roughness, torn grain, fuzzy grain, Industriell teknik och ekonomi - Övrig industriell teknik och ekonomi
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-35381 (URN)9e610f1a-aaa0-4735-9311-ba5f8c931e06 (Local ID)978-0-9947964-0-0 (ISBN)9e610f1a-aaa0-4735-9311-ba5f8c931e06 (Archive number)9e610f1a-aaa0-4735-9311-ba5f8c931e06 (OAI)
Conference
International Wood Machining Seminar : 14/06/2015 - 17/06/2015
Note

Godkänd; 2015; 20150625 (micohm)

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Ekevad, M., Cristovao, L., Grönlund, A. & Öhman, M. (2014). Geometry of kerf when curve sawing with a circular rip-saw (ed.). Paper presented at . European Journal of Wood and Wood Products, 72(6), 809-814
Open this publication in new window or tab >>Geometry of kerf when curve sawing with a circular rip-saw
2014 (English)In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 72, no 6, p. 809-814Article in journal (Refereed) Published
Abstract [en]

Rip-sawing following the curvature of a crooked log means advantages for yield. However, the possibility to saw in a narrow curve with a circular saw blade is limited because of the inherently flat geometry of circular saw blades. For a double arbour circular saw the situation is even more problematic because the two blades have a certain overlap and thus, the two arbours are not positioned in the same horizontal position. In this study, a theoretical geometrical study of the creation of a kerf with a single circular saw blade and with a double arbour circular saw with two saw blades was examined. Results for stiff saw blades show that the kerfs become in general curved and inclined (tilted) in the vertical direction and also that the width of the kerfs for double arbour saws becomes wider at the top and bottom of the cant than in the middle. Additionally, the sawn boards obtain varying thickness along their width because of the varying kerf width. A comparison with experimental thickness data from four test sawings at a sawmill indicates that the theoretical results are valid and that curve sawn boards become thinner than straight sawn boards.

National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-2796 (URN)10.1007/s00107-014-0832-6 (DOI)000343877800011 ()2-s2.0-84920710494 (Scopus ID)07eca113-84d7-496c-b1a7-08a88b00e9e3 (Local ID)07eca113-84d7-496c-b1a7-08a88b00e9e3 (Archive number)07eca113-84d7-496c-b1a7-08a88b00e9e3 (OAI)
Note
Validerad; 2014; 20140806 (matse)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Sandberg, D., Vaziri, M., Trischler, J. & Öhman, M. (2014). The role of the wood mechanical industry in the Swedish forest industry cluster (ed.). Paper presented at . Scandinavian Journal of Forest Research, 29(4), 352-359
Open this publication in new window or tab >>The role of the wood mechanical industry in the Swedish forest industry cluster
2014 (English)In: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 29, no 4, p. 352-359Article in journal (Refereed) Published
Abstract [en]

The forest and forest products form one of the most important basis for the transfer to a biobased economy in Sweden. About 75% of the area covered by forest in Sweden is used industrially to produce raw material for the wood-refining industries. Every year, this cluster uses 75 million m3 of roundwood and has an export value of € 12 billion. This review paper is devoted to the wood mechanical industry, i.e. the industry which turns the forest into sawn timber, packaging, construction wood, furniture and interior fittings. The sawmills consume about half of the volume of softwood which is felled, and about two thirds of the sawn timber goes to export without any further refining within the country. Nevertheless, in spite of the relatively low degree of refinement in the sawmill and the fact that the sawmills in general over time have a very low profitability, they are responsible for 70–80% of the forest owners' profits on the sale of timber. An increased upgrading of the sawn timber within the country is desirable from a national economic viewpoint – increased employment opportunities, increased export income etc. It should then in the first place be for products with a higher added value, such as furniture and fittings. Today, the refinement value is 15–20 times higher for products from joinery and furniture industries compared that of the sawn timber and the added value of the wood within the building industry is only about 1.5 times.

National Category
Other Mechanical Engineering
Research subject
Wood Technology
Identifiers
urn:nbn:se:ltu:diva-4701 (URN)10.1080/02827581.2014.932005 (DOI)000339920100007 ()2-s2.0-84904765271 (Scopus ID)2af2d770-5d8d-43c8-8ebd-d2d04c5615a0 (Local ID)2af2d770-5d8d-43c8-8ebd-d2d04c5615a0 (Archive number)2af2d770-5d8d-43c8-8ebd-d2d04c5615a0 (OAI)
Note
Validerad; 2014; 20140619 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2247-674x

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