What you need is a Cable Stripper for stripping MICC/MIMS/PYRO (or whatever you want to call it)
Available from all good electrical wholesalers or companies like RS.
I made my own by welding some 8mm bar into a "T" shape then slotting the end with a hacksaw for about 15mm.
It takes a bit of practice but with a pipe cutter to score the sheath and some side cutter snips it works OK, and can strip any diameter without adjustment. "I love deadlines. I love the whooshing noise they make as they go past." Douglas Adams