Quartz glass is a special glass material known as “King of Glass”. The silicon purity of the quartz glass is very high, therefore it is excellent in heat resistance, chemical resistance and optical transparency as compared to other glasses, such as borosilicate glass.
At present, it is used in the production field of leading-edge. Now researches are carried out to develop it as key components of special manufacturing equipment, scientific instruments and analysis equipment that require high-precision, high purity, the high light transmittance. However, due to its high heat resistance, it is difficult to be processed into various shapes. As a result, manufactured quarts glass products, generally, might be different even in one batch. To respond to such products for precision instruments, it is preferable to select the heat molding process by flame called “fire-process” in many cases. “fire-process” is the process of forming a softening point of heated quartz glass material by a mixed combustion flame of hydrogen and oxygen. Therefore, a technique for forming a glass material softened by heating is required, and now it is done by human hand processing of engineers. While skilled human technique of long time experience is required in order to produce high precision and an efficient products. Therefore digitizing and analysis of the work of expert engineers with high level of hand skill is needed to increase the processing technology of the engineers less skilled and take advantage in the manufacture of high-precision products. In this study, the differences in the working process between engineers with different years of experience during the “fire-process” of quartz glass material were analyzed. Fire-process is of heating joint glass cylinders during rotating using a dedicated glass lathe machine. The working behaviors of three operators were recorded by videos during “fire-process”. And the thickness of jointed part of final products was measured by ultrasonic equipment to evaluate the quality of the jointed situation. It is found that these differences in the process of heating joint of glass cylinder have effects on the accuracy of finial production and the manufacturing efficiency.