Digital-imaging-based cost-efficient ball-pressure indentation measurement

Ball-pressure test has been widely implemented as a method for testing heat endurance of non-metallic materials of electrotechnical equipments. The test result is determined by the valid diameter of indentation at the tangent points, not the complete indentation. At present most tests are based on experience, and are subjected to various problems due to personal difference. In this paper, a cost-efficient and precise digital-imaging testing system is proposed. The algorithm is based on the difference of reflection effect due to material distortion, and with automatic digital-imaging recognition, the valid diameter is calculated. The result has been proved to be in accordance with the result of 3D scanning. Based on the problems emerging in this process, some areas for further study are suggested.