Influence of Machining Parameters on the Tensile Strength of Finger-Jointed High-Density Black Spruce Lumber


  • Roger E. Hernández
  • Razvan Coman
  • Robert Beauregard


Finger-jointing, wood machining, black spruce, cutting speed, chip load


Finger-jointed softwood lumber is widely used in manufacturing of structural or nonstructural applications such as glued laminated lumber and prefabricated wood I-joists. Black spruce is the most frequently used species for finger-jointed engineered wood products in eastern Canada. However, some key machining parameters must be adjusted according to the properties of the wood to obtain a surface quality suitable for the finger-jointing process. The main objective of this study was to evaluate the effect of cutting speed and chip load on the ultimate tensile strength (UTS) of finger-jointed high-density black spruce. The variables were four cutting speeds and three chip loads. A feather profile was selected with an isocyanate adhesive and an end-pressure of 3.45 MPa. A factorial analysis showed a statistically significant interaction between cutting speed and chip load on UTS and cutting speed was the most significant variable. The influence of chip load on UTS was lower, apparent only at 3260 m/min cutting speed. Suitable finger-jointing could be achieved at 1860-3960 m/min cutting speed with a chip-load of 0.51-1.27 mm. However, the best result was obtained at 3260 m/min cutting speed and 0.89 mm chip load. These results need to be validated in industrial mills to verify tool wear behavior.


AceCo (2002) Wood tooling catalog and technical manual. AceCo Precision Manufacturing, Boise, ID. 66 pp.nASTM (1995) Standard test methods for specific gravity of wood and wood-base materials. D2395-93. ASTM, West Conshohocken, PA.nASTM (2000) D1990. Standard practice for establishing allowable properties for visually-graded dimension lumber from in-grade tests of full-size specimens. American Society for Testing and Materials, West Conshohocken, PA.nASTM (2004) D5457. Standard specification for computing the reference resistance of wood-based materials and structural connections for load and resistance factor design. American Society for Testing and Materials, West Conshohocken, PA.nASTM (2005) D198. Static tests of timbers in structural sizes. American Society for Testing and Materials, West Conshohocken, PA.nAyarkwa J, Hirashima Y, Sasaki Y (2000a) Effect of finger geometry and end pressure on the flexural properties of finger-jointed tropical African hardwoods. Forest Prod J 50(11/12):53-63.nAyarkwa J, Hirashima Y, Sasaki Y, Ando K (2000b) Effect of glue type on flexural and tensile properties of finger-jointed tropical African hardwoods. Forest Prod J 50(10):59-68.nBustos C (2003) Optimisation du procédé d'aboutage par entures multiples du bois d'épinette noire. PhD Thesis, Université Laval, Quebec, Canada. 133 pp.nBustos C, Beauregard R, Mohammad M, Hernández RE (2003a) Structural performance of finger-jointed black spruce lumber with different joint configurations. Forest Prod J 53(9):72-76.nBustos C, Mohammad M, Hernández RE, Beauregard R (2003b) Effects of curing time and end-pressure on the tensile strength of finger-jointed black spruce lumber. Forest Prod J 53(11/12):85-89.nBustos C, Hernández RE, Beauregard R, Mohammad M (2004) Influence of machining parameters on the structural performance of finger-joined black spruce lumber. Wood Fiber Sci 36(3):359-367.nCaster D, Kutscha N, Leick G (1985) Gluability of sanded lumber. Forest Prod J 35(4):45-52.nChen G (2001) Two-part polyurethane adhesive for structural finger joints. Industrial applications of isocyanates and polyurethanes. Pages 15-16 in The wood adhesives 2000 symposium. Section 2A: Industrial applications of isocyanates and polyurethanes. Forest Products Society, South Lake Tahoe, CA, 22-23 June 2000.nCollins M, Walford B (1998) Recent research into structural fingerjointing. New Zealand Engineering. Construction and Construction Materials 53(6):24-26.nCSA (2006) CAN/CSA-O122-06. Structural glued-laminated timber. Canadian Standards Association, Mississauga, Ontario, Canada.nHernández RE (1994) Effect of two wood surfacing methods on the gluing properties of sugar maple and white spruce. Forest Prod J 44(7/8):63-66.nHernández RE, de Moura LF (2002) Effects of knife jointing and wear on the planed surface quality of northern red oak wood. Wood Fiber Sci 34(4):540-552.nHernández RE, Naderi N (2001) Effect of knife jointing on the gluing properties of wood. Wood Fiber Sci 33 (2):292-301.nHernández RE, Rojas G (2002) Effects of knife jointing and wear on the planed surface quality of sugar maple wood. Wood Fiber Sci 34(2):293-305.nJessome AP (2000) Résistance et propriétés connexes des bois indigènes au Canada. Forintek Canada Corp. Séries: Publication spéciale SP514F. Ste-Foy, Quebec, Canada. 37 pp.nJokerst RW, Stewart HA (1976) Knife-versus abrasiveplaned wood: Quality of adhesive bonds. Wood Fiber Sci 8(2):107-113.nKennedy DE (1951) Glued, laminated construction (Chapter 11). Pages 281-292 in TA McElhanney and JH Jenkins, eds. Canadian woods: Their properties and uses. Canada Department of Resources and Development. Forestry Branch, Forest Products Laboratories Division, King's Printer, Ottawa, Ontario, Canada.nKnowles CD (2003) Wood properties of finger-jointed southern pine. Master Thesis, Stephen F. Austin State University, Nacogdoches, TX. 157 pp.nKnowles CD (2006) Characterization of selected wood properties in commercially produced southern pine finger-jointed dimension lumber. Forest Prod J 56 (9):43-46.nKoubaa A, Isabel N, Zhang SY, Beaulieu J, Bousquet J (2005) Transition from juvenile to mature wood in black spruce (Picea mariana [Mill.] B. S. P.). Wood Fiber Sci 37(3):445-455.nKutscha NP, Caster RW (1987) Factors affecting the bond quality of hem-fir finger-joints. Forest Prod J 37 (4):43-48.nMarra AA (1992) Technology of wood bonding: principles in practice. Van Nostrand Reinhold Co, New York, NY. 454 pp.nNLGA (2003a) NLGA SPS 2. Special products standard for machine graded lumber. National Lumber Grades Authority, Vancouver, BC, Canada. 34 pp.nNLGA (2003b) SPS 1. Special products standard for fingerjointed structural lumber. National Lumber Grades Authority, Vancouver, BC, Canada. 31 pp.nNLGA (2003c) SPS 4. Special products standard for fingerjointed flange stock lumber. National Lumber Grades Authority, Vancouver, BC, Canada. 41 pp.nRaknes E (1982) The influence of production conditions on the strength of fingerjoints. Pages 154-168 in Proc., Production, Marketing and use of fingerjointed sawnwood. United Nations Economic Commission for Europe. CFL Prins, ed. Martinus Nijhof/Dr. W. Junk Publishers, The Hague, The Netherlands.nReeb JE, Karchesy JJ, Foster JR, Krahmer RL (1998) Finger-joint quality after 4, 6 and 32 hours of knife wear: Preliminary results. Forest Prod J 48(7/8):33-36.nSAS (2004) SAS/STAT users' guide, version 9.1. SAS Institute Inc, Cary, NC.nSelbo ML (1963) Effect of joint geometry on tensile strength of finger joints. Forest Prod J 13(9):390-400.nSelbo ML (1975) End and corner joint construction. Pages 49-55 in Adhesive bonding of wood. Technical Bulletin No. 1512. USDA. Forest Serv., Washington, DC.nSingh AP, Anderson CR, Warnes JM, Matsumura J (2002) The effect of planing on the microscopic structure of Pinus radiata wood cells in relation to penetration of PVA glue. Holz Roh Werkst 60(5):333-341.nSt-Pierre B, Beauregard R, Mohammad M, Bustos C (2005) Effect of moisture content and temperature on tension strength of fingerjointed black spruce lumber. Forest Prod J 55(12):9-16.nVrazel M, Sellers T Jr. (2004) The effects of species, adhesive type, and cure temperature on the strength and durability of a structural finger-joint. Forest Prod J 54 (3):66-75.nWisconsin Knife Works, Inc (2000) Premium Cutting Tools, 07/00 Catalog. Beloit, WI. 112 pp.n






Research Contributions