ULTRASONIC MEASUREMENT AND CONTROL OF SURFACE ROUGHNESS

THE AMPLITUDE OF ULTRASOUND REFLECTED OR SCATTERED FROM A SOLID SURFACE IN A FLUID DEPENDS ON THE RELATIVE ACOUSTIC IMPEDANCES OF THE MEDIA AND ALSO ON THE SURFACE ROUGHNESS OFTHE SOLID. A VERY SMOOTH SURFACE WILL TEND TO REFLECT A HIGHER ULTRASONIC AMPLITUDE THAN A ROUGH ONE. A ROUGH SURFACE WILL LEAD TO SIGNIFICANT SCATTER INTENSITY, MEASUREMENTS OF ULTRASONIC REFLECTIVITY AND SCATTER, THEREFORE, MAY BE USED TO DETERMINE SURFACE ROUGHNESS AND TO MONITOR ROUGHNESS WHILE A MATERIAL IS BEING MACHINED. THUS, ULTRASONIC MEASUREMENTS OFFER PROMISE FOR DYNAMIC (IN-PROCESS, REAL-TIME) MONITORING OF MACHINING PROCESSES TODETECT VARIATIONS IN SURFACE ROUGHNESS AND TO RELATE THE MEASUREMENTS TO WEAR OR BREAKAGE OF THE CUTTING TOOL. IN THIS PROGRAM WE PROPOSE TO MEASURE ULTRASONIC REFLECTION ANDSCATTER FROM METAL SURFACES WITH THREE DIFFERENT ROUGHNESS VALUES. THE MEASUREMENTS WILL BE DONE OVER A RANGE OF ULTRASONIC FREQUENCIES AND SCATTER ANGLES. THESE RESULTS WILL LEAD TO IMPROVED UNDERSTANDING AND A MODEL THAT WILL PROVIDE INSIGHT FOR THE DEVELOPMENT OF AN ULTRASONIC INSTRUMENT FOR DYNAMIC SURFACE ROUGHNESS MEASUREMENT AND FOR THE CONTROL OF MACHINING PROCESSES.