The detection of knots in wood materials using the tracheid effect

2007 ◽  
Author(s):  
Ilkka P. Jolma ◽  
Anssi J. Mäkynen
Keyword(s):  
Tracheid Effect

scholarly journals Increased yield of finger jointed structural timber by accounting for grain orientation utilizing the tracheid effect

2019 ◽  
Vol 77 (6) ◽  
pp. 1063-1077
Author(s):  
Anders Olsson ◽  
Andreas Briggert ◽  
Jan Oscarsson
Keyword(s):  
Grain Orientation ◽  
Minimum Distance ◽  
Fibre Orientation ◽  
Structural Timber ◽  
Finger Joint ◽  
European Standard ◽  
Clear Wood ◽  
Finger Joints ◽  
Tracheid Effect

Abstract Finger joints in structural timber and glulam lamellae are often used to enable production of long members or to allow for re-connection of parts of a member after removal of weak sections. According to the European Standard EN 15497, certain margins are required between knots and a finger joint in structural timber, which means that a considerable amount of clear wood becomes waste when finger joints are applied. The purpose of this paper was to investigate the possibility of reducing the quantity of waste using different criteria for placement of finger joints. The investigation was based on (1) application of methods of colour scanning and tracheid effect scanning to detect knots and grain disturbance on board surfaces, and (2) interpretation of the requirements of EN 15497 regarding where finger joints may be placed. The standard’s requirement when producing finger joints is that the minimum distance between a knot and a finger joint is three times the knot diameter. The standard allows for the minimum distance between a knot and a finger joint to be shortened to 1.5 times the diameter when the local fibre orientation is measured. Utilizing this in simulated production resulted in reduction of waste from 7.4 to 4.0%, when using finger joints simply to produce timber of long lengths. If finger joints are also used to re-connect parts of members after removal of weak sections, even larger savings can be made. Furthermore, it is concluded that knowledge of fibre orientation obtained from scanning could be used not only to decrease the waste in production but also to increase the quality of finger joints.

TRACHEID EFFECT SCANNING AND EVALUATION OF IN-PLANE AND OUT-OF-PLANE FIBER DIRECTION IN NORWAY SPRUCE TIMBER

2018 ◽  
Vol 50 (4) ◽  
pp. 411-429 ◽  
Author(s):  
Andreas Briggert ◽  
Min Hu ◽  
Anders Olsson ◽  
Jan Oscarsson
Keyword(s):  
Norway Spruce ◽  
Fiber Direction ◽  
Out Of Plane ◽  
Tracheid Effect
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