Non-Contact Measurements for Industrial Quality Control

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The proposed research aims to develop improved methods for non-contact testing and quality control of industrial products and processes. Such techniques are attractive because they minimally impact production flow. They can give real-time information and allow prompt decision making for material quality and process control. To give a specific focus, I have framed my research program from the perspective of two applications of non-contact testing in the wood industry, but practical applications reach substantially beyond. The proposed work extends and builds on prior research on the development of non-contacting optical and X-ray sensors for material quality control in the wood industry. LUMBER GRAIN ANGLE MEASUREMENT To compete effectively in the international market, Canadian sawmills must produce the highest value products from the available raw material. For construction products, wood strength is a primary focus. However, the substantial variability of wood presents a serious challenge to strength assessments, so quality control becomes very conservative. While of good safety, this approach seriously wastes a lot of high value material. The strength of wood depends directly on grain direction. A deviation of about 15 deg. halves wood strength. Consequently, grain angle is a very effective wood strength indicator. Established measurement methods are limited because they can measure only the surface (in-plane) grain angle, but not the diving (out-of-plane) angle. The directional reflection method explored here is unique in that it can measure both angles. The method exploits the characteristic of a wood surface to reflect incident light preferentially in a plane perpendicular to the grain. In the proposed work, a measurement device of novel geometry is explored to enable grain angle profile scans to be made over a wide range of grain angles. INDUSTRIAL SAWBLADE TENSIONING MEASUREMENT In sawmills, the wood raw material consumes about 75% of total costs. Thus, it is very important that industrial saws should be as thin as possible to produce minimum sawdust waste, while also being thick enough to cut in a straight line. The allowable sawblade thickness can be further reduced by inducing stresses into the saw body by a process called "tensioning". To determine effective processing conditions, it is necessary to assess each saw individually. This assessment involves observing very small shape changes that are difficult to measure in a consistent way. Electronic Speckle Pattern Interferometry (ESPI) is proposed here as a means of measuring the small deformations in sawblades. The shearographic ESPI technique is particularly well suited because it measures surface slope and so can better detect local deformation details.