Nickel-based superalloys have long been recognized as difficult-to-machine alloys. Chipping and breakage are understood as the dominant features of tool deterioration particularly in milling of these alloys. But how tool deterioration affects cutting force (Fc) has not been sufficiently established so that force model base deterioration detection methods can be practically developed. Thus, this study intends to better demonstrate the relationship between modes of tool deterioration and Fc. Milling experiments were conducted using 718Plus superalloy and uncoated cemented carbide tool and a commonly used set of milling parameters, with or without the use of coolant. During these experiments, Fc was recorded and in between milling passes the traditionally used flank wear value (VB) was precisely measured. We have observed that as milling progressed, along with the slow edge wear, edge chipping and fracturing intensified and Fc increased. However, before the final catastrophic failure, the rate of increase was relatively small in comparison to the scatters in Fc vs VBMax plot. Thus, a model based on Fc vs VBMax for detection of tool deterioration may not be suitable. We will explain the reasons for the scatters and relate the fracturing path to the effect of it to cutting edge contact area, thus to Fc.

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