Research on the path and velocity of spatter in manual metal arc welding

Summary

In this paper we studied the loci (paths) and the velocities of scattering spatter in shielded metal arc (MMA) welding with high titanium oxide type electrodes. We examined only spatter that flew off at a right angle to the weld line and passed through a slit of 4 mm by 75 mm. The loci of the spatter were photographed when they scattered in the air and their velocities were calculated from the camera shutter speed. We also simulated the loci and velocities of the spatter and the experimental data and the calculated values were compared.

In the experiment we examined 110 spatter particles whose diameters ranged from 0.1 to 1 mm. The spatter particles flew around on the surface of the base metal within a 500 mm radius circle. They flew in the air for less than about 0.5 seconds. And the highest velocity was 6 m/see. The Reynolds numbers of the spatter were less than 7. They were given by Re = d × V/1 (d is the diameter of spatter. V is the velocity of the spatter v is the coefficient of kinematic velocity). And the coefficient of kinematic viscosity of the air was calculated using the temperature. The temperature was determined by the arithmetic mean of the temperature of spatter particles (given they were 1637 K) and the temperature of the air (293 K). To simulate the loci and the velocities of the spatter, the equation of motion is set up under a certain condition. The condition is that the temperatures of the scattering spatter are constant and their drag coefficients (Cd) are given by the Stokes equation for a sphere (Cd = 24/Re). The calculated value by this equation matches well the experimental results, though the former were a little larger than the latter in almost all cases.