Need device that converts mechanical energy to thermal energy?

Answer 1

Almost every mechanical device converts some of its mechanical energy

to thermal energy.

Some examples I can think of at the moment are:

-- drill bit

-- saw blade

-- file

Answer 2

One common device that converts mechanical energy to thermal energy is a friction heater. Friction heaters such as brake pads or clutches use the mechanical energy generated from friction between two surfaces to produce heat. Another example is a hand-cranked generator that produces electricity, which can then be converted into thermal energy using resistive heating elements.