Laser deposition of stainless and tool steel on a copper-beryllium alloy for plastic injection mould improvement

Abstract

In the plastic industry the cycle time for the injection of each piece is fundamental for the profitability of the process. One method to reduce the injection time is to manufacture the moulds with a copper-beryllium (Cu-Be) alloy, providing a unique combination of thermal conductivity (i.e. shorter cycle time), strength, dimensional control and excellent corrosion resistance. However, for certain plastic processing applications, the medium hardness of the Cu-Be alloy leads to early wearing in critical areas, mainly close to the injectors and in sharp corners. In this study, two laser techniques were used for improving and repairing those areas of Cu-Be moulds. On one side, laser cladding with a martensitic type 431 stainless steel powder with higher hardness (>50 HRc) than the copper-beryllium alloy (∼35 HRc) was performed. On the other side, manual laser welding with tool steel filler wire addition was also used. With both laser techniques, no pre- or post-heat treatment was applied. The results for the parametric and metallurgical studies, comparing both techniques, are presented in this study. The modified moulds were tested under normal working conditions, and resulted in significant costs reduction.In the plastic industry the cycle time for the injection of each piece is fundamental for the profitability of the process. One method to reduce the injection time is to manufacture the moulds with a copper-beryllium (Cu-Be) alloy, providing a unique combination of thermal conductivity (i.e. shorter cycle time), strength, dimensional control and excellent corrosion resistance. However, for certain plastic processing applications, the medium hardness of the Cu-Be alloy leads to early wearing in critical areas, mainly close to the injectors and in sharp corners. In this study, two laser techniques were used for improving and repairing those areas of Cu-Be moulds. On one side, laser cladding with a martensitic type 431 stainless steel powder with higher hardness (>50 HRc) than the copper-beryllium alloy (∼35 HRc) was performed. On the other side, manual laser welding with tool steel filler wire addition was also used. With both laser techniques, no pre- or post-heat treatment was applied. The results for the...