X-ray system assesses wood strength
Certain uses of lumber--such as for roof trusses--require the strength of the wood to be accurately assessed. This so-called machine-stress-related (MSR) lumber has tight specifications on its strength and stiffness. While a given lumber type has relatively constant characteristics, knots or other deformities can reduce strength considerably.
Traditionally, MSR lumber is tested by applying a shear force to it. Weaker lumber sometimes breaks, jamming testing machines. Often, shear test equipment cannot apply stress to the full length of the wood. By replacing this method with an automated x-ray system, developers at Newnes Machine (Salmon Arm, BC, Canada) can measure the strength of a complete length of lumber. As the wood passes under the x-ray source, attenuation caused by the lumber is detected by an x-ray detector. Raw x-ray data are then processed to determine the board`s strength.
