A tool-chip thermocouple is used to measure the cutting temperature in a turning operation. The two dissimilar metals in a tool-chip thermocouple are the tool material and the work piece metal. During the turning operation, the chip from the work metal forms a junction with the rake face of the tool to create the thermocouple at exactly the location where it is desired to measure temperature: at the interface between the tool and the chip. A separate calibration procedure must be performed for each combination of tool material and work metal. In the combination of interest here, the calibration curve (inverse transfer function) for a particular grade of cemented carbide tool when used to turn C1040 steel is the following: T = 88.1Etc - 127, where T = temperature in (F, and Etc = the emf output of the thermocouple in mV.
(a) Revise the temperature equation so that it is in the form of a transfer function similar to that given in Eq. (6.3). What is the sensitivity of this tool-chip thermocouple?
(b) During a straight turning operation, the emf output of the thermocouple was measured as 9.25 mV. What was the corresponding cutting temperature?