Real-time on-machine observations close to interelectrode gap in a tool-based hybrid laser-electrochemical micromachining process

Abstract

A tool-based hybrid laser-electrochemical micromachining process involves concurrent application of two process energies i.e. electrochemical and laser in the same machining zone by means of a hybrid tool which serves as an ECM tool as well as a multimode waveguide. It is a relatively novel process finding applications in defect-free machining of difficult-to-cut materials without affecting their microstructure. In order to understand the physical phenomena occurring during this process, in-situ observations are required. Therefore, in this work, a real time observation was carried out of a novel tool-based hybrid laser electrochemical micromachining process. A combination of high-speed imaging and Large Scale Particle Image Velocimetry (LSPIV) was used to visualize the tool-based hybrid laser-ECM process in real time. It also allowed to carry out experimental investigations on the by-products and bubble generation which have a direct effect on process performance in terms of accuracy and efficiency. The real-time on-machine observations are unique of its kind and they will facilitate the understanding of underlying mechanisms governing this hybrid laser-electrochemical micromachining process. This will ultimately help in improving the quality of parts manufactured. This research is also a step forward towards making these physics-based hybrid processes deterministic by employing high-speed imaging in a closed loop control.

Electrochemical jet manufacturing technology: From fundamentals to application

“…Jiang et al [136] subsequently applied the system to create Ni-Co-SiC deposits with enhanced mechanical and corrosion properties and substrate adhesion (0.8 A/cm 2 , 0.5 T). The authors observed a (111) crystallographic texture, which was enhanced when depositing from higher SiC concentration electrolytes. This was associated with the greater deposition of Co 2+ , which is reported to interact more strongly with SiC than Ni 2+ .…”

“…Generated gases and debris will delocalise and attenuate the laser in an unpredictable manner, which challenges appropriate focussing [111]; this also complicates translational milling. Therefore, alignment is generally undertaken manually prior to EJM, and the laser will drift or become unfocussed upon material removal.…”

“…Saxena et al [109,112] developed new hybrid machine-tool and dedicated tooling designed for laser jet ECM methods consisting of a quartz capillary within a stainless-steel tube, enabling the application of LA-EJP towards larger component geometries without the need to refocus between operations. Real-time on-machine high-speed camera observations near the IEG in combination with particle image velocimetry analysis [111] revealed that LA-EJP also accelerates generation of by-products (including hydrogen bubbles) that require removal to achieve synergistic benefits of both processes. When high flow rates are applied to facilitate flushing, there is a trade-off as enhanced convective cooling of the workpiece surface reduces laser heating.…”

“…30d-e). The authors reported a Ni-Co solid solution (fcc), indicating compositions below 60 wt.% Co, and a textural preference towards (111).…”

Gas Bubble Evolution during ECM Process can be suppressed by Pulse Parameters: High Speed Videographic Observations during Early Stages of Bubble Evolution

“…They measured the time at which the electrolyte starts boiling under different parameter settings. Saxena et al [16] employed large scale particle image velocimetry (PIV) to understand the transportation and flow velocities during ECM process which was subsequently followed in the work of Tchoupe et al [17] where PIV was applied in conjunction with dynamic similarity (scaling of IEG) to understand the transport of gas bubbles in ECM. Rommes et al [18] applied PIV in conjunction with laser sheet to understand gas transport over a larger processing area.…”