I have an oscillating steel blade cutting soft plastic at 8000 oscillation/minute and 9 in/minute feed and I wish to calculate the blade temperature. Even simplified calculations would help... How should I go about it?
In my experience, calculating the heat generated by the process is considerably easier than determining where the heat goes.
In your example you're going to have the heat going at least four places; the saw blade, the soft plastic, the chips and the environment.
If you can do it, direct observation is the way to go. Can you use an IR gun on the saw blade while it's running? If you can focus on the outside of the blade immediately as it exits the cut you might get an idea.
Another option is to measure the temperature of the stop saw blade after cutting and then calculate the rate of heat loss.
One of the considerations is figuring out which part of the saw blade to measure. Typically the tips are going to get much hotter than the body if there is proper side clearance. Typically the heat moves from the outside in.