I recently changed jobs to a manufacturing role within the automotive industry and went to change my IOSH group to one that would either cover Manufacturing or Engineering and to my surprise there is no group covering this industry sector

Why not and how do i go about requesting one, none of the other groups fit what i do now

It is interesting that in the country cited as starting the Industrial Revolution a.k.a. Manufacturing a professional organisation seems to overlook the continued, albeit diminished, presence of a particular sector with most groups being either specialised high risk (aviation) or service industry (consultancy).

But then why would you chose to be pigeon holed? That is typically the remit of inusrance underwriters.