Heat comes from friction
A bit that rubs more than it cuts turns energy into heat. Causes may include low feed, excessive spindle speed, a dull bit or unsuitable depth of cut.
Quick checks
Inspect the cutting edge, runout, clamping, chip evacuation and workpiece stability. Very fine dust instead of chips can indicate inefficient cutting.
Correct progressively
Change one parameter at a time and test on scrap. Stop immediately if smoke, smell or temperature rises abnormally.
Important
The stated parameters are starting points. Test progressively on scrap and always respect manufacturer limits.