Atmospheric pressure plasmas: A review

Thermodynamic and transport properties of high temperature equilibrium air plasmas have been calculated in a wide pressure (\(0.01\div100\) atm) and temperature range (\(50\div60\,000\) K). The results have been obtained by using a self-consistent approach for the thermodynamic properties and higher order approximation of the Chapman-Enskog method for the transport coefficients. Debye-Hukel corrections have been considered in the thermodynamic properties while collision integrals of charge-charge interactions have been obtained by using a screened Coulomb potential. Calculated values have been fitted by closed forms ready to be inserted in fluid dynamic codes.

Thermodynamic and transport properties in equilibrium air plasmas in a wide pressure and temperature range

Plasma arc cutting (PAC) is a highly promising thermal cutting process because of its wide industrial applications involving cutting of different materials at high speeds. The competing abilities of PAC with laser cutting combined with its less polluting nature have shifted the research attention towards the process. The cutting parameters like arc current, torch stand-off, cutting speed and gas pressure play an important role in determining the quality of a cut surface. In the present work, the quality characteristics of the cut surface were assessed by measuring the surface roughness and kerf width while cutting the 304 L stainless steel. The experimental trials were designed by Taguchi’s L18 orthogonal array unlike the central composite design used with traditional response surface methodology (RSM), and an integrated approach of Grey Taguchi-based response surface methodology (GT-RSM) was disclosed for predicting the optimal combination of cutting parameters. The GT-RSM approach was found to improve the quality characteristics studied in the work significantly. The results will offer a good cutting database for the textile, chemical and pharmaceutical processing industries.

Application of Grey Taguchi-based response surface methodology (GT-RSM) for optimizing the plasma arc cutting parameters of 304L stainless steel

An optimization concept of the various machining parameters for the plasma arc cutting procedures on AISI 316 stainless steel conducting a hybrid optimization method has been carried out. A new composition of response surface methodology and grey relational analysis coupled with principal component analysis has been proposed to evaluate and estimate the effect of machining parameters on the responses. The major responses selected for these analyses are kerf, chamfer, dross, surface roughness and material removal rate, and the corresponding machining parameters concentrated for this study are feed rate, current, voltage and torch height. Thirty experiments were conducted on AISI 316 stainless steel workpiece materials based on a face-centered central composite design. The experimental results obtained are applied in grey relational analysis, and the weights of the responses were evaluated by the principal component analysis and further evaluated using response surface method. The results show that the grey relational grade was significantly affected by the machining parameters directly as well as with some interactions. This method is straightforward with easy operability, and the results have also been established by running confirmation tests. The premise attributes beneficial knowledge for managing the machining parameters to enhance the preciseness of machined parts by plasma arc cutting.

Y.S Lu

Papers

Study on ceramic cutting by plasma arc