Realistic characterisations of the frictional behaviour at the chip-tool contact region and material flow properties are most critical for successfully simulating metal machining. This paper deals with the former aspect and it describes some recent experimental and theoretical research on the modelling of friction for use in metal cutting simulations. It presents four such models, one obtained from continuous development of the other. The models have been tested against experiment and each other by implementing them in an existing finite element simulation of machining. It has been shown that different friction models used to represent the same friction data yield different simulation results, in particular, the temperature distributions and contact lengths. It has also been shown that friction modelling can be effective up to a certain stage where the information about material flow characteristics at levels observed in machining becomes important. Further exploration of this should be one of the prime areas of machining research.