With the correct grade and type of media and the right operating pressures components are dimensionally unaffected and threads, bearing housings etc. are not damaged...Obviously an unsuitable, coarse media applied at high pressures could detrimentally affect surface finish and dimensions..We've all heard the stories of castings that end up looking like they've been shot peened...However, a suitable media for blasting rusted iron barrels for example wouldn't be selected for aluminium components...
For some items a two stage method would be used...It's a common misconception that in all cases blasting is an aggressive method of surface finishing when in fact glass, plastics and many other materials can be treated in this way without damage to the surfaces...Ian
