the setting of the completely different parameters can obtain different weld for example the structure changes will not be the same width. it is possible to obtain a smaller heat-affected zone (haz) and a plastically affected zone (paz). the width of the weld is smaller. the results are for example not the same in welds made for the european space agency with a high turnover ω = 14000 rpm or another example in warsaw technical university 12000 rpm and very short friction time only 60 ms instead of using an standard parameters, in addition, in this case, ultra fine grain alloy was welded. unfortunately the diameter of the workpiece can be a limitation to the use of high speeds of rotation.