It is possible to obtain several products by glueing wood. Internationally approved standards require wood adhesion to be tested according to standardized procedures, including in the results, shear stress and wood failure percentages. In order to estimate wood failure percentage, the ASTM D5266-99 standard suggests the use of a grid template printed on a transparent sheet. However, this evaluation is not only time-consuming but also subjective. This work developed and tested an algorithm to quantify the flawed wood areas by using a machine vision system, a faster and less subjective procedure. Two types of automatic threshold algorithms were tested. The glued wood samples were scanned after the shear tests under compression. It was concluded that automatic measurement can replace the manual grid method. The proposed algorithms presented an average absolute error of 3%, as compared to the manual grid method.
Image processing; wood; adhesion; automation
