New method of sheet thickness inspection: improvement in the accuracy of the thickness measuring system during the manufacturing process

The measurement of thickness of various sheets, such as foamed, multi-layered, 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 sensing system are used to measure the thickness of various sheets. However, it is important to precisely measure the thickness of sheets during the manufacturing process. In the present study, a new system for inspecting the sheet thickness is realized which results in accurate measurements. With the use of a calibration gauge, it was found that the thickness measuring system drastically improved the inspection of sheet thickness without use of a standard sheet, resulting in a precision of /spl plusmn/0.5% or less for a composited sheet thickness of 730 /spl mu/m during the manufacturing process.