Nondestructive insitu-evaluation of powder compact in pressing by the ultrasonic array-sensing

Various quantitative nondestructive evaluation (QNDE) methods have been and still are subjected to highlight in research and development to promote the quality of PM materials. One of the most promising methodologies is an ultrasonic measurement method to be working even on process. Authors have been developing the ultrasonic array sensing system for on-process assessment of varying geometry and dimension of green compacts and change of their elastic properties and porosity structures. In our developed proto-type system, any pairs of ultrasonic transducers can be systematically chosen to make data correlation for data processing. Hence, geometric configuration change of PM parts in pressing can be traced on-time or on-line together with direct estimate of the change of elasticity in densification. Our developed ultrasonic array sensing system for QNDE in CIP is briefly introduced with some comments on the ultrasonic spectroscopy where visco-elasticity of materials should have macroscopic correlation with phase shift and frequency spectrum. Aluminum powder compaction by CIP is employed as a targeting forming for on-line assessment of change of geometric configuration and porosity structure in pressing.