UNLOCKING THE SECRET OF FINGER-JOINT STRENGTH - THE SIGNIFICANT CORRELATION BETWEEN FINGER- JOINT STRENGTH AND GLUE SPREAD RATE

摘要

This study was conducted to quantify the relationship between finger-joint strength and glue spread rate. A total of 48 finger-joint lumber specimens were made using an isocyanate (ISO) adhesive, while 36 specimens were made with a phenol-resorcinol (PRF) adhesive. The profile, geometry, and machining parameters of the finger-joints were maintained constant while the glue spread rate was varied. The measurements included the amount of fresh glue applied to each joint and the joint tensile strength. A significant correlation was found between the tensile strength of the joints and the fresh glue spread rate. The relationships were best described by quadratic equations, with a correlation coefficient (r) of 0.91 for the ISO joints and 0.89 for the PRF joints. It is concluded that the glue spread rate is a very important parameter affecting finger-joint strength, and that attention should be paid to maintain the glue spread rate constant when finger-joint specimens are prepared to study the effects of other parameters on finger-joint strength.