Tom,
The estimated machining times in Creo are terrible. Given that it is such a powerful program I don't understand why they haven't tried to make it more accurate. All other systems that I've used have given options for spindle ramp up and ramp down time and rapid accel and decel.
In order to get my time in the "ballpark" I had to adjust my tool change time to over double what it is at the machine, and I have my rapids set at 300 ipm for a machine with 1100 ipm rapids. This still only gives me a very rough estimate since it really depends on the lengths of my rapid moves.
Heres to hoping Creo 3 has some of these features....
