Asperity Junction-Growth Inhibition

There are circumstances under which no firm evidence, either direct or indirect, can be found for the formation or existence of an additive interaction film and yet the behavioral signs of additive action are unmistakable. Such situations generally involve short times of contact with drastic surface changes and severe wear. 

It has been demonstrated (72, 73) that access of cutting fluid to the chip-tool rubbing interface is via the clearance gap at the flank of the tool and then past the cutting edge. Only minute quantities of cutting fluid can get to the rubbing zone by this route. Furthermore, the contact time of the chip with the tool face is very short at a cutting speed of 0.508 m/s (100 ft/min) an element of chip surface traverses the contact zone in 30 microseconds. Moreover, the chip never returns to rub the face of the tool therefore any reaction of the free chip surface 

To explain the pronounced effect of additives on tool wear in metal cutting, Dorinson [74] developed a theory of the inhibition of junction growth at contacting asperities based on the concept of dynamic competition between asperity adhesion and the quenching of such adhesion by additive reaction. The adhesion mechanism involves the following sequence migration of metal on the chip side of the contact interface to the tool side, 

If it is assumed that fe2 t then the last two terms of Eqn 10-19 can be dropped altogether and the term mfe2 can be omitted from the denominator of the first term Eqn 10-19 can then be shortened to the approximation below  

If now we introduce the postulate that the wear rate is proportional to we can write 

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