Analysis of coaxial vision systems for real-time Z-height control for laser cladding process

Direct manufacturing and particularly Direct Metal Deposition (DMD) is one of very promising processes which interest many industries as it offers the possibility to directly generate the real part from file CAD without tooling (reduction of the deadlines, realization and costs) and makes it possible to produce parts with equivalent characteristics even higher than those obtained with the traditional processes as machining. In order to ensure a metallurgical and dimensional good quality of the parts without having to make long and expensive controls, it is essential to implement an inline process control. This step necessarily passes through an instrumentation of the output parameters of the process. In the first part, we present the DMD process and overview of the problem. Measurements of output parameters are made by a dedicated coaxial sensor based on CMOS cameras that we present in the next section. Different optical principles and setup as defocusing and stigmometer are reviewed and analysed. Then, w...