carbon/ali tooling

To save me having to work the old grey matter too much has anyone got any figures for the break off point where it becomes more cost effective to have cnc machined Ali moulds as opposed to tooling block patterns/prepreg moulds ?
If this comes off it has the potential to ne a long run but would really know at what point the Ali moulds start paying for themselves ?
Mostly single part moulds with a few 2 part moulds all small/medium sized
Anyone ?

Thats a very difficult question to answer. There are many factors that would go in to choosing your tooling medium. Besides cost, you have to consider performance of the tooling vs your process. In the case that either aluminum or carbon tooling can do just fine for you, it really comes down to costing out each option based on that specific project.

What I would suggest is that you make an excel worksheet that calculates all your cost for different tooling types, so that it is faster to input project details and get an output to compare. Takes a little bit of time to make this excel tool the first time but fully worth it in the end