Lumber Defects Research Articles

REDUCTION OF EFFECT OF GROWTH STRESS PRESENCE USING ENDLESS SCREW DURING KILN DRYING AND STEAMING AND HEATING TREATMENT IN LOG BEFORE SAWING

The relaxation of growth stress in trees growing in fast-growth conditions, as plantation in tropical areas, affects lumber quality during of sawing or drying process. It was evaluated two pretreatments (heating and steaming application) before sawing process and endless screw use to maintain the boards pressed during drying ofDipteryx panamensisand Hieronyma alchorneoideswood with objective to reduce the effects of relaxation of growth stress. Theresults showed endless screw is used to maintain the boards pressed, the moisture content (MC) or drying rate did not vary. The use of endless screws with daily adjustment during drying produced a reduction of cup, check and split defects in lumber and this treatment is accompanied with a pre-treatment before sawing (heating or steaming treatment) decreased theincidence of drying defects. Then the use of both treatments is an opportunity to reduce theeffects of relaxation of growth stress on the quality of the wood of D. panamensisand H.alchorneoidesfrom fast-growth plantation conditions.

Ways to increase the production efficiency of hardwood blanks

The article presents the main results of experimental studies on the identification of the main grade defects of oak lumber by the thermal non-destructive testing method. Regressional dependences of wood defects temperature display from the main factors for the studied grade defects are proposed. Indicators of infrared radiation (temperature range) of the main visible oak grade defects obtained as a result of experimental studies are presented. A conceptual scheme for the line control methods of identification of the main grade defects in lumber are proposed.

Failure Analysis of Glulam Lumber Beam Made from Meranti Lumber Pieces (Shorea SP)

The development of glue-laminated (glulam) lumber beam gives many good results. Meranti (Shorea SP) is one of the construction lumber that can be used as glulam to optimize its use. The limitation of the glulam lumber beam is the limited length of the lumber, so it must be joined to get a certain length. The lumber available in the market on average has a limited size and cross-sectional length. The larger the cross-sectional size and length of the lumber make the higher the price. Used lumber and residual lumber also have many weaknesses, such as the length of suitable lumber is too short, lumber defects, and lumber damages. Further research needs to be done to optimize the use of new, used, and residual meranti lumber through the use of lumber pieces as a glulam lumber beam maker. Standard specimen and test based on ASTM D-198. Glulam lumber beam is made from pieces of meranti lumber planks of certain length which are arranged into lamina beam with the size of 5.5x9.5x150 cm3. Variations in the length of the pieces of meranti lumber planks for making glulam lumber beam, among others, 40 cm, 50 cm, 60 cm, 50 cm with full length lowest layer and 150 cm (full length). The adhesive used is polyurethane glue. The span between supports is 130 cm. The beam is tested for center point loading. The analysis results show that the joints on the outermost layer that receive tensile stress of the glulam lumber beam can cause weakening in the beam because the tensile strength of the adhesive is weaker than the tensile strength of lumber. Failure at the tensile joint of the outer layer of the beam can trigger a shear failure mode. Design of joints should not be placed on layers that are subject to tensile stresses so as not to trigger shear failure modes so that the strength of the glulam lumber beam can be optimal.

Surface growth stress and wood properties of 8-year-old planted Big-leaf mahogany (Swietenia macrophylla King) from different landrace provenances and trial sites in the Philippines

The scarcity of timber to supply the wood-based industries is one of the prevailing problems worldwide. Tree plantations are the remaining solutions to subdue the shortage of raw materials, at the same time sequester atmospheric CO2 in its biomass to reduce global warming. Planting Big-leaf mahogany (Swietenia macrophylla King) contributes valuable economic inputs to small tree farmers in the Philippines. However, the occurrence of lumber defects during processing due to growth stresses reduces the potential value of timber. This study aimed to examine the differences of surface growth stresses and wood properties of an 8-year-old BL mahogany from six landrace provenances in two progeny trial sites, Butuan and Cagayan de Oro in the Philippines. The longitudinal released strains of the surface growth stress (SRS) were not significantly different among six landrace provenances and between two trial sites. The SRS were not significantly related to diameter at breast height (DBH) in both trial sites. The high level of negative SRS was observed in some tested trees with small diameter in both trial sites, which was attributed to the tension wood formation in an irregular-shaped stem. The xylem density (XD), average microfibril angle in the secondary cell wall (MFA), vessel element length (VL) and vessel element width (VW) had no significant differences among six landrace provenances. In terms of trial sites, Butuan trial site gave high lateral growth DBH, high XD, longer fiber length (FL) with a narrow fiber width (FW) and smaller MFA as compared to the Cagayan de Oro trial site. It was observed that an 8-year-old BL mahogany plantation with small-diameter trees exhibited high SRS, low XD, small FL, wide FW and large MFA, which are passively considered as properties of juvenile wood.

Defects and grading after kiln drying hardwood lumber sawn from small-diameter logs

Close inspection of black cherry (Prunus serotina), sugar maple (Acer saccharum), and northern red oak (Quercus rubra) lumber, before and after kiln drying, revealed the factors that can affect the quality of kiln-dried lumber from small-diameter logs. Species-specific kiln drying schedules, with temperature and humidity modifications formulated by a kiln drying expert, were employed in this study to determine whether alternate drying protocols could improve the drying outcomes. Comparing lumber grades of individual boards before and after drying indicated that overall grade loss in the kiln was common but was affected by both species and the applied drying schedule. Most lumber defects were attributed to stresses that occurred during the drying process and were more prevalent in the post-drying inspection, with bow defects being the exception. The modified kiln schedules improved the drying defect outcomes for the black cherry and red oak compared with the conventional schedules for these species. For the sugar maple, the schedule-based improvement was less consistent. For the black cherry and red oak, the percentage of boards whose grade decreased using conventional kiln protocols was approximately 10% lower than that of the lumber that was dried using the modified kiln protocols. Sugar maple had a smaller change of 7%.

Deep learning for use in lumber classification tasks

Digital image processing has been widely used in the wood industry, and it is expected that the algorithms are accurate and have low computational complexities, especially for the real-time lumber grading and lumber classification processes. This paper investigates variations of deep learning strategies based on ResNet18 for classification of lumber images. The four datasets used in this work were manually marked as lumber defects, wood textures and lumbers by experts. A key ideal is to employ the transfer learning in the context of convolutional neural networks with a classifier layer only training with a small amount of training data for different tasks at the same lumber machinery. Through the expansion of unbalanced samples, the accuracy rate has been effectively improved. The human involvement when needed is kept to a minimum only for the training phase. The proposed approach was independently tested with four datasets, of which 80% of the data is used for training and 20% of the data is used for testing. The classification accuracy of the approach for each of the datasets is 98.16%, 93.32%, 96.64% and 99.50%. The average time for sorting the lumber image was kept at 0.003 s when the system runs on Nvidia GTX860 GPU.

Defect detection performance of automated hardwood lumber grading system

This paper describes the abilities of the Microtec Goldeneye 300 Multi-Sensor Quality Scanner™ to recognize and identify defects for purpose of grading kiln dried, rough, hardwood lumber using the GradeView™ grading algorithm. The overall accuracy of the automated grading system was found to be 92.22% on grade and 99.50% on value as defined by the National Hardwood Lumber Association sales code, well within industry standards. We also discuss the small number of boards that were graded incorrectly by the system and specifically how the multi sensor scanner detects various lumber defects. This scanner has six different types of sensors-color cameras, black and white cameras, profile cameras, line lasers, dot lasers and an X-ray that work together to provide accurate detail for lumber grading.

О нормировании пороков на пиломатериалах

О нормировании пороков на пиломатериалах

Using pedicled rectus abdominis musculocutaneous flaps in thigh and lumber defects

A series of previously described but rarely used variations of the pedicled, extended or vertical rectus abdominis musculocutaneous flap (Extended RAM, VRAM) were reviewed. Skin paddle dimensions, ranged 8 to 28 cm in width and 10 to 35 cm in length, were used in five consecutive patients. Four flaps were placed deep to the inguinal ligament to repair the thigh as proximal to the knee region; the remaining one flap was passed transabdominally to cover the defect of the lumbar region. No flaps necrosis were seen and in one case wound healing problems required minimal operative intervention. Successful transfer of the VRAM and extended RAM with low rate of complication for the thigh and lumbar region defects were demonstrated to be safe and reasonable options of flap reconstruction. The flaps had the advantages of being robust and well-vascularized, easy and fast to harvest, and not requiring microsurgery experience.

Thermographic, ultrasonic and optical methods: A new dimension in veneered wood diagnostics

Modern production techniques in the wood-based industry reached a high quality standard at high output rates. While the speed of the production machines increases, it is necessary to introduce modern and faster working online inspection methods to supervise constantly the material for defects. For example, thermographic cameras are able to detect not only invisible defects within wood-based materials like laminated particle and fiberboards, but can be used also to detect defects in lumber and veneered wood [1–4]. In the latter case, there is the need to inspect more accurately the final pieces, given the exponential growth in worldwide sales. Therefore, in order to minimize adhesion problems [5], detecting surface and sub-surface cracks, define the geometry of the sub-surface detachment, in the veneered wood products, an integrated non-destructive test method is needed both during the production process that after to it [6]. Our system can provide a continuous control of the process and the product. In fact, this study compares the performance of transient thermography, three optical methods and ultrasonic testing applied together on a veneered wood sample with real and fabricated defects. The use of phase-shifting holography correlated to Double-Exposure HI and the wavelet transform applied as fusion of images between Thermographic Signal Reconstruction and Double-Exposure HI, are explored in this work.

Research on the Intelligent Manufacturing System for Lumber Cutting

To enhance the rate of lumber cutting output and save the production cost, a new intelligent manufacture system is developed. Considering the requirements of wood surface defects detection and optimal layout, the overall structure is established. The system has six function modules, there are cutting task module, laser scanning images processing module, defects identify module, optimal layout module, machining plan module and data manage module. According to laser scanning, images processing and defects identify programs help manufacturer to get profile data, acquire profile image, extract features, and identify lumber defects. Optimal layout module gives an intelligent program to decide the maximum number of cutting board pieces and shows operator the visualized layout. Two examples are shown which apply algorithms to obtain the optimal layouts for lumber cutting. The intelligent manufacturing system helps people detect lumber defects, make the optimal machining plan and cutting material online quickly.

Establishing Kiln Drying Schedule for Beech (Fagus orientalis) at 5-cm Thickness from the Neka Region

To establish a kiln drying schedule for beech (Fagus orientalis) lumber, 5-cm-thick boards were kiln dried down to a final moisture content of 8%. Three replications were made utilizing three kiln schedules of T5-C3, T5-C4, and T6-C4. With due attention to the effect of thickness on wood drying intensity, the t-test showed no significant difference between the thicknesses of the three drying schedules at a significance level of 99%. Therefore, the results of this study can be applied for 5-cm-thick boards. The primary dry bulb temperature in each of the three schedules was adjusted to 41°C and the final dry bulb temperatures were adjusted to 71, 71, and 82°C, respectively. The schedule offering the shortest drying time for the desired quality was chosen. Specific gravity and dry specific gravity were measured as 0.52 and 0.61, respectively. Longitudinal, radial, tangential, and volumetric shrinkage were 0.46, 5.8, 10.2, 16.48%, respectively. The extent of defects including crook, bow, twist, and three longest surface checks of the lumber was determined for each drying schedule. Quality control graphs were used to analyze the lumber defects in order to determine the best drying schedule. Analysis of the results indicates that with either of three kiln schedules the extent of defects before and after drying was not statistically different. However, the distribution of defects in the third schedule (T6-C4) was more uniform with respect to the average line compared to other two schedules. At the end of this schedule, a 17-h equalization and 24-h conditioning treatment is recommended.

Quantitative Identification of Defects in Lumber Based on Modal Frequencies and Artificial Neural Network

This study preliminarily discussed a new method to identify the location and size of internal wood defects using experimental modal analysis (EMA) and artificial neural network. The different defect sizes and locations were simulated by removing mass from intact wood specimens. At room temperature in the laboratory, free vibration testing was conducted to generate the frequency response functions (FRF) of intact and defective Korean Pine (Pinus koraiensis) wood specimens using fast Fourier transform (FFT) analysis system. The first three orders intrinsic frequencies were captured by picking up the location of each order peak of FRF curves. Then, two identification indexes developed by previous research were constructed based on these intrinsic frequencies, and they were used as input parameters to build the networks for localization and size determination of wood defects respectively. These two artificial neural networks were trained and tested for wood defects recognition. The research results showed that: (1) the intrinsic frequencies of defective wood were lower than those of intact wood; and (2) the constructed two identification indexes were capable to effectively detect the location and size of wood defects, which were more sensitive to large size defects than small size defects.

An investigation of the use of active infrared thermography to detect localized surface anomalies in lumber

Efforts are being pursued to improve and automate processes for grading, trimming, and cutting up softwood and hardwood lumber by automated, non-contact, non-labor-intensive methods. Existing technology for detecting defects in lumber has focused heavily on the use of charged coupled device scanners or cameras, but these devices are limited by inherent color differences of the material. Thermography has been proven to detect knots in lumber, but the use of active thermography has not been investigated in terms of detecting dents, holes, and gouges. This research focused on four heating techniques, i.e. defect side heating, back side heating, forced air heating, and pulsed thermography, to detect dents, holes, gouges, and knots. All four heating methods proved successful for at least two defect types. Implementation of these techniques in an industrial setting will depend on the requirements of the manufacturer and the physical limitations of the industrial line.

Impact of the white pine weevil (Pissodes strobi [Peck]) on Norway spruce (Picea abies [L.] Karst.) plantations. Part 2: Lumber properties

We studied the lumber characteristics of 148 trees acquired for that purpose during commercial thinning operations in three Norway spruce (Picea abies [L.] Karst.) plantations, aged from 32 to 34 years, which had been attacked repeatedly by the white pine weevil (Pissodes strobi [Peck]). The trees, with diameters ranging from 14 to 23 cm, were grouped into three quality classes according to the number of major deformations caused by the weevil. The effects of the deformations on bending strength and stiffness, wood density and lumber defects were examined. Results show that in general deformations caused by the weevil do not affect the lumber properties of Norway spruce on sites of medium to high quality. For the three Norway spruce plantations, the mean values of the modulus of elasticity (MOE) of the lumber varied between 8510 and 9357 MPa, and for the modulus of rupture (MOR) they ranged from 36.0 to 42.5 MPa, whereas wood density varied from 324 and 343 kg·m-3. For comparison purposes, the same measurements were taken on lumber from 38 trees in a white spruce (P. glauca [Moench] Voss) plantation that was unaffected by the weevil, but comparable to the Norway spruce plantation on one of the sites studied. The lumber properties from Norway spruce taken from deformed or undeformed stems were 34% superior to white spruce for MOE, 20% for MOR and 8% for wood density. The smaller knots in Norway spruce could explain this difference. On the other hand, a visual grading of this type of wood reveals few differences in lumber strength and stiffness. Key words: Norway spruce, Picea abies, wood characteristics, MOE, MOR, wood density, lumber, white pine weevil, Pissodes strobi, white spruce, Picea glauca

Impact du charançon du pin blanc (Pissodes strobiPeck) dans les plantations d’épinette de Norvège (Picea abies(L.) Karst.). Partie 2 : Propriétés du bois des sciages

We studied the lumber characteristics of 148 trees taken for that purpose during commercial thinning operations in three Norway spruce (Picea abies [L.] Karst.) plantations, aged from 32 to 34 years, which had been attacked by the white pine weevil (Pissodes strobi [Peck]). The trees, with diameters ranging from 14 to 23 cm, were grouped into three quality classes according to the number of major deformations caused by the weevil. The effects of the deformations on rigidity, bending strength, wood density and lumber defects were examined. Results show that in general the deformations caused by the weevil do not affect the lumber properties of Norway spruce on sites of medium- to high-quality. For the three Norway spruce plantations, the mean values of the modulus of elasticity (MOE) of the lumber vary from 8510 to 9357 MPa, and for the modulus of rupture (MOR) range from 36.0 to 42.5 MPa, whereas wood density varies from 324 to 343 kg·m-3. For comparison purposes, the same measurements were taken on lumber from 38 trees in a white spruce (P. glauca [Moench] Voss) plantation that was unaffected by the weevil, but otherwise comparable to the Norway spruce plantation on one of the sites studied. The lumber properties from the Norway spruce taken from deformed or undeformed stems are 34% superior to the white spruce for the MOE, 20% for the MOR and 8% for wood density. The smaller knots in the Norway spruce could explain this difference. On the other hand, a visual classification of this type of wood reveals few differences in the lumber's bending strength or rigidity. Key words: Norway spruce, Picea abies, wood characteristics, MOE, MOR, wood density, lumber, white pine weevil, Pissodes strobi, white spruce, Picea glauca

Softwood Lumber Grading through On-line Multivariate Image Analysis Techniques

The concepts behind the use of multivariate image analysis (MIA) techniques for on-line monitoring of subtle features in time varying images were presented in an earlier paper (Bharati, M. H.; Macgregor, J. F. Ind. Eng. Chem. Res. 1998, 37, 4715). This paper illustrates the successful application of these ideas to an industrial process from the forest products industry. MIA is used to rapidly detect the presence and quantity of common lumber defects such as knots, splits, wane, pitch, and bark pockets in individual sawn lumber boards as they pass on a moving conveyor belt under a line-scan RGB camera. Multiway principal component analysis is used to decompose the acquired three-channel lumber images into a two-dimensional principal component (PC) space. Masking score point clusters in the score space and highlighting corresponding pixels in the image space of the two dominant PCs enables isolation of lumber defect pixels based on contrast and color information. Control charts with appropriate tolerance limits are set up to monitor counts of defective pixels lying under any defect mask in the MIA score plots for each new lumber sample as it passes through the imaging system. Those lumber samples violating the tolerance limits are automatically downgraded. This application of on-line MIA for assessing specific quality problems is not limited to lumber grading, but could be directly applied to many industrial processes involving the production of solid or heterogeneous liquid or liquid/solid products.

Potential of two processing methods to reduce sweetgum and sassafras lumber defects

Sassafras and sweetgum logs were grade sawn and the lumber milled to 4/4 thickness and processed according to two methods. One half of the boards of both species were ripped prior to drying and the other half were dried prior to being ripped to the desired dimension. A statistical analysis revealed that the non-conventional method gave a significantly greater twist, crook, and crook per foot than the conventionally processed boards for both species. Sassafras boards produced with the non-conventional method had significantly higher bow and bow per foot than conventionally processed boards. It is emphasised that our non-conventional method did not follow the Saw-Dry-Rip (SDR) methodology.

Preliminary investigation of the feasibility of using acousto- ultrasonics to measure defects in lumber : Lemaster, R.L.; Dornfield, D.A. Journal of Acoustic Emission, Vol. 6, No. 3, pp. 157–165 (Jul./Sep. 1987)

Preliminary investigation of the feasibility of using acousto- ultrasonics to measure defects in lumber : Lemaster, R.L.; Dornfield, D.A. Journal of Acoustic Emission, Vol. 6, No. 3, pp. 157–165 (Jul./Sep. 1987)