There is no single answer to that question. The speed you can run a 1/32" bit will depend on a lot of factors: material, depth of cut, z-axis feedrate, acceleration capability of your machine, amount of relief in the model. In general if you try to push a 1/32 bit too fast in hard material you run a good chance of breaking it, especially if the roughing pass has left a lot of material. If there is lot of relief to the model, then any cut with a vertical component will only go as fast as the slowest feedrate - so even if you set XY to 200 ipm, if your Z is set to 40, then 40 is what you'd get on surfaces where the bit is moving in Z. If there is a lot of movement required for the model then a machine with slower acceleration will never get up to the requested feedrates anyway. I've had a lot of models where I requested 200ipm or more with a 1/8" ballnose and never even approached that speed in reality because of the amount of movement/start/stops required to do the carving.
40 is not a bad place to start. You can try pushing it to 60 or 80. A 1/32 ballnose will always take a long time any any carving of any size, however. Unless something is really tiny, I usually don't see any advantage in going below 1/16", and most of my carvings are with a 1/8" ballnose.
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