### Contents of Journal of Mechanical Engineering 55, 1 (2004)



DEEPAK, K. P., NIBEDITA, D., RAJAT, K. B.: Predicting material
removal in electro-discharge machining                                      1

HAMMAD, M. M. S.: A study on possibility of using reversed heat
treated steel with little carbon for manufacturing functional
parts of agricultural machines                                             23

ADAMCZAK, S., MAKIELA, W.: Influence of work centre displacements
on the estimation of roundness profiles measured with reference
methods                                                                    33

BAHLAOUI, A., RAJI, A., HASNAOUI, M.: Coupling between mixed
convection and radiation in an inclined channel locally heated             45



# Abstracts

### Predicting material removal in electro-discharge machining

KUMAR PANDA DEEPAK, DASH NIBEDITA, KUMAR BHOI RAJAT

Various researchers have predicted the crater under single spark by considering the thermal erosion theory. Theoretical models have been developed by solving the transient heat conduction equation considering suitable assumptions with appropriate initial and boundary conditions. For the sake of close-form solution, too many assumptions and simplified initial conditions resulted in solution, which is far from reality. In actual machining, the growth of plasma channel, energy sharing between electrodes, vaporization of workpiece, formation of recast layer, temperature sensitivity of thermal properties of material are few physical phenomena encountered which have not yet been considered mathematically. Therefore, direct correlation of theoretical prediction of material removal with the experimental results has not yet been done. In such circumstances an attempt has been made to apply the factorial design in conjunction with multiple regression to develop response equation to predict the material removal rate.

### A study on possibility of using reversed heat treated steel with little carbon for manufacturing functional parts of agricultural machines

Through using reversed heat treatment, possibility to improve the mechanical characteristics of steel with little carbon and using thereof in field of manufacturing functional parts of agricultural machines, which have direct contact with soil, was studied.

Experiments proved that reversed heat treatment helps to increase hardness of a little carbon steel as well as its wear resistance against abrasive wear in the soil through depending on hardening temperature and how its internal structure is distributed.

Upon reversed heat treatment of a little carbon steel, the best results of hardening were obtained from 780oC, where increase of hardness presented 35 % and increase of resistance against abrasive wear in the soil represented more than five doubles compared with ferrite - pearlite steel, which is used for manufacturing of agricultural machines parts. This fact affirms possibility of improvement of mechanical characteristics of a little carbon steel and possibility of using thereof in agricultural mechanism field.