The objective of this research is to study the influences of blowing gas pressure, liquid tin temperature and gas nozzle angle on the preparation of tin powders smaller than 75 microns by gas atomization. This procedure was preceded by using horizontal gas atomizer and Nitrogen gas blowing. The experiment was a fractional factorial design of 2³. The 3 treatments and 2 levels were the blowing gas pressure at 50 and 200 pounds per square inch, the liquid tin temperature at 300 and 500° C, and the gas nozzle angle at 30 and 60 degrees. The experimental results show that the blowing gas pressure at 200 pounds per square inch, liquid tin temperature at 300° C and gas nozzle angle at 30 degrees produced the maximum quantity of tin powders smaller than 75 microns, average 56.12%.  The tin powders were spherical shape. The experimental results were analyzed by Minitab program and found that the positive influence was the blowing gas pressure and the negative influences were the gas nozzle angle and liquid tin temperature. The influence sequences were a blowing gas pressure, a gas nozzle angle and a liquid tin temperature with 95% confidence level.

Key words: tin powder,   atomization, gas pressure, temperature, gas nozzle angle.