Guys thank you for the replies
I was really hoping that this was a simple box i havent ticked or a setting that i havent added. But unfortunatley unbending and cutting the mitre out and then bending back looses all the time that i saved using the flange command in the first place.
Because this material ranges from 1-3mm the curves that creo create are only a hinderance to the fabricator who punches and laser cuts these parts so a requirement for the 0 bend allowance and straight edges is a must in manufacture time.
They K factor that is currently in use is 0.3 but the fabricator calculates the developed length and width by adding the inside bend dimensions.
the flange in the project is 50mm the inside lenght is 300mm and width 100mm
the bend dimensions on the flat pattern thus should measure the the same however they measure 100.71 and 50.36 respectivley, this leads me to belive that the incorrect flat pattern is used to achieve what the fabricator requires so i am going to change the k factor try and achive the correct bend dimensions i shall return to the forum later and let you guys know if this makes any differnce to flat result.
Again many thanks for your answers to this frustrating problem.