PURPOSE: To heat raw rubber for tires, etc. uniformly within a short period with the energy and space therefore saved, by irradiating the raw rubber with high-frequency waves before it is masticated so that the raw rubber is heated to a specific temperature.

CONSTITUTION: In case that the raw rubber should be masticated after it is heated, the raw rubber before it is masticated is irradiated continuously or intermittently with high-frequency waves of 0.2W40kW.min/kg so that the rubber is heated to about 50W60°C.

EFFECT: The raw rubber can be uniformly heated to a suitable temperature within a short period, that is, about 30W60min. The thermal efficiency is good, the energy therefore can be saved, and the space for the facilities can be minimized.