The nugget size is also an important critical parameter
in determination of spot weld quality [1]. Therefore, the
diameter or width of the fused zone must meet the requirements
of the appropriate specifications or the design criteria.
The spot weld that is reliably reproduced under normal
production conditions should have a minimum nugget
diameter of the 3.5–4 times the thickness of the thinnest
outside part of the joint [1]. The relationship between nugget
size and peak weld current was determined in this
study. The result is shown graphically in Fig. 5. The measured
weld nugget size was found acceptable that is approximately
three times of the thickness of the outside part of
the joint (Fig. 4).