Improving the performance of domestic pin punches using failure analysis investigation techniques

The study investigates the failure of locally manufactured pin punches, aiming to identify the factors contributing to these failures and to improve performance and production processes in line with international standards. The target performance benchmarks were 1 million punches for M50 steel (the original material) and 250 thousand punches for D2 steel (an equivalent material), both measured after heat treatment and coating with a TiN layer. Key factors examined in the investigation included excessive pressure, design flaws, material selection, heat treatment, and the machining process. Various analytical techniques, such as chemical analysis, mechanical testing, and imaging methods (including optical and scanning electron microscopy), were employed to analyze the samples. Upon examining the primary samples, mechanical fatigue was identified as the primary failure mechanism. The research involved experimenting with different tool steels and evaluating their performance. The study explored the use of SLIPPNER and D2 steels as alternatives to M50 steel. Initially, controlled heat treatment processes for SLIPPNER were conducted in salt furnaces, followed by machining of the pin punches. This process led to a significant increase in production rates, reaching 140 thousand punches compared to the previous 10 thousand. Subsequently, with D2 steel, a complete change in the heat treatment process, applied in two different methods and followed by controlled finishing, led to remarkable results. The performance improved dramatically, surpassing 1.5 million punches "after heat treatment and without a TiN layer," with the punches still operational to date.