Abstract
The sizes of bead and weld bead appearance of weldments are expected to depend on the skills of welder operating such as semi-automatic welding machine. The visual examination is probably the one most widely used to evaluate the skills of welding operatives. The visual examination can appropriately judge the weld bead appearance, but this examination has the problems such as objectivity and unevenness of evaluate by differences among individuals. It is therefore desirable to understand the statistical properties of bead sizes such as bead width, bead height and bead appearance. This paper describes the statistical properties of sizes of bead width and bead height in butt welding joints with backing plates which are welded by welding operators having the specified welding skills using the semi-automatic MAG welding machine. The results obtained may be summarized as follows:
(1) The distribution properties of mean bead width, maximum bead width and maximum difference in bead width are clarified, and they conform to a normal distribution.
(2) The distributions of mean bead height, maximum bead height and maximum difference in bead height are made clear and also they adjust to a normal distribution.
(3) 95% confidential intervals of mean value of populations such as mean bead width, and mean bead height in butt welding joints with backing plate welded by welding operatives having the license SN-2F (JIS Z3841) using MAG welding machine.
