Thickness Measurements of Plastic Sheets during the Manufacturing Process: Comparison of Errors with Soft X-ray Thickness and the New Laser Measuring Systems

With the development of advanced technology, there has been an increased demand for polymer sheets for use in various applications, along with the requirement to measure the thickness of such sheets. The measurement of thickness of various sheets, such as foamed, multilayered, composited, and perforated sheets has increased in many different applications. The present authors have developed a system in which a magnetic sensor and an optical sensor system, employed during the manufacturing process, are used to measure the thickness of various sheets, termed the new laser thickness measuring sensing system. In general, the thickness of uniform sheets has been measured using beta ray or soft X-ray measuring systems, in which transmitted or absorbed rays were needed to maintain safe working conditions. The application of these methods, however, to sheets having composited and multilayered structures of different densities, or those with foamed structures, results in large measuring errors due to basis weight measurements. The present study compares the results of measurements of thickness with the new laser and previously used soft X-ray thickness measuring systems, and discusses the errors found in sheet thickness measurements