Engineering and Technology Journal

Vibration implementation that assists metal forming has many advantages, such as enhancement of surface equality, reducing the forming force and decreasing the stresses. The technology of single-point incremental forming with all the above-mentioned advantages has been performed with the vibration. This paper focuses on the average surface roughness (Ra) improvement of the final product by using the vibration. The average roughness was found to be affected by vibration of the sheet metal. The combination of vibration produced a better surface quality of the forming shape by using an active damper to control the vibration.  For determining the damping ratio, which gives the necessary roughness, an artificial neural network (ANN) was created based on experimental results. A feed forward neural network with Liebenberg–Marquardt back propagation algorithm was utilized for building the artificial neural network model (3-n-1). Confirmation runs were conducted for verifying the agreement between the predicted results of ANN with those of the experimental outcomes. As a result, the product surface quality is increased where the surface roughness was reduced by (18%) from the surface roughness without vibration. The best reduction rate was in the axial forming force at (100 Hz) frequency, where the reduction rate was about (11.64%) from the force without vibration.

Thermal barrier coatings (TBCs) are used in advanced engines working at higher temperatures. Higher efficiency and performance of gas turbine engines will require careful selection of TBCs. In this study, Ni22Cr10Al1.0Y (Amdry 9625) bond coat and two types of top coat including ceria stabilized zirconia (CSZ) ZrO2-24CeO2-2.5Y2O3) and yttria stabilized zirconia (YSZ) ZrO2-8Y2O3 were deposited on IN 625 by air
plasma spraying (APS). The thickness of the duplex ceramic coat based on zirconia was in the range between 350 to 400 μm. The effect of high power Yb:YAG solid state laser at different laser parameters on feature, microstructure and roughness of plasma sprayed and laser sealed coating of multilayer ceria stabilized zirconia/ yttria stabilized zirconia was investigated. Surface roughness has been reduced significantly after laser sealing. The effect of laser process parameters carried out using Taguchi’s L16 orthogonal array design. Minimum roughness can be obtained at moderate power density and longer interaction time with sufficient specific energy to produce complete melting of coating. Characterization and analysis of results was achieved by employing scanning electron microscopy (SEM) , (EDS) and image J analysis. It was found from the results, there were significant improvements in the performance of plasma sprayed coatings after laser sealing due to the reduction of surface coating defects.

Chemical machining is a well-known nontraditional machining process and is the controlled chemical dissolution of the machined work piece material by contact with a strong acidic or alkaline chemical reagent. It is also called as chemical etching. The present work is aimed at studying the effect of machining time, machining temperature, etching solution concentration on the surface finish of stainless steel 304 using mixed of acids (HCL+HNO3+HF+ H2SO4+H2O). Alloy samples are of (33×33×6) mm dimensions. Three machining temperatures (45, 50 and 55 ºC) for each of which three machining times (3, 6, and 9 min) were used as machining conditions. Surface roughness increases with the machining temperature and machining time. An assessment of CHM was achieved by empirical models for selecting the appropriate machining conditions of the required surface finish. The models were designed based on multiple regression method via Mtb 16 software.