Development of a Teaching Tool which Measures the Surface Roughness of Metals: A Simple Surface Roughness Meter Using a Semiconductor Laser
Toshikazu YAMAMOTO, Ryoya MAKINO, Masahiro UEDA
In the junior high school metal working area of the Industrial Arts and Home Making program the final process of material production is, in many cases, a surface treatment such as painting. This is a very important process because making the metal surface smooth will protect the surface from corrosion, and further, give it beauty. The process of surface treatment starts with rough sandpaper and gradually progresses to finer sand paper until the surface looks glossy. It is of fundamental importance for students to develop the ability to evaluate the finished condition of the surface by looking at it or touching it. It is difficult, however, for beginning students to precisely evaluate the condition of the surface using sight and touch only. Therefore, a teaching tool that assists the students in determining the degree of polishing at the completion of each step is desirable. We developed a simple surface roughness meter to quantitatively measure the degree of surface roughness, and conducted an experimental lesson using it. The concept behind this teaching tool involves measuring the surface roughness in a simple way by pointing the irradiated laser light (from a semiconductor laser) on the surface and measuring the intensity of the reflected light. This teaching tool has made it possible for students to make a numerical estimation and therefore a pertinent evaluation of the surface roughness. Using this device, student products have made remarkable improvement and efficient exercises have become possible. The method of producing this tool is also described for the benefit of those who would like to make one.
Key words :metal working, surface roughness, semiconductor laser, evaluation of product