Excess welding area localisation and profile modelling on distorted surface in turbine component repairing process

Although numerical machining is normally employed in the mass-production of precision parts, there still exists a significant industry in Singapore that depends on human skill and mediated NC operations to perform component repairs and overhaul, especially for the aerospace industry sector, called turbine overhaul services. The reason is that turbine components are often severely distorted and have to be replaced and repaired after a number of service cycles in high-temperature, high-pressure environment. The repairing process starts with cleaning and covering the defective areas with the braze material. The excessive material is to be removed from distorted or unknown surface within the required tolerance. The process is done manually world wide currently. The key problem here is how to remove excessive material without under cut and over cut on a distorted or unknown surface. To empower the machining system with adaptivity and intelligence, an innovative solution has been developed. The measurement data from an in-situ non-contact measurement sensor is processed, and used to localise the welding/one with excess materials and generate 3D surface. Such a measurement-based, CAD-free approach allows the machining system to be adaptable to distorted or unknown surfaces. The profile measurement strategy, software/hardware architecture, data processing and surface modelling algorithms and results are described and discussed in this paper.