Measurement of Transient Tool-Internal Temperature Fields During Hard Turning by Insert-Embedded Thin Film Sensors

Abstract

This paper presents a novel approach for obtaining thermal data from the close vicinity (70–700 μm) of the tool-workpiece interface while machining hardened steel. Arrays of microthin film C-type thermocouples with a junction size of 5 μm × 5 μm were fabricated by standard microfabrication methods and have been successfully embedded into polycrystalline cubic boron nitride (PCBN) using a diffusion bonding technique. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were performed to examine material interactions at the bonding interface in order to determine optimal bonding parameters. Static and dynamic sensor performances have been characterized. The sensors exhibit excellent linearity up to 1300 °C, fast rise time of 150 ns, and sensitivity of ∼19 μV/ °C. The PCBN inserts instrumented with embedded thin film C-type thermocouples were successfully applied to measure internal tool temperatures as close as 70 μm to the cutting edge while machining hardened steel workpieces at industrially relevant cutting conditions. Correlations between temperature and cutting parameters have been established. The embedded microthin film sensor array provided unprecedented temporal and spatial resolution as well as high accuracy for microscale transient tool-internal temperature field measurements. Tool-internal temperature maps were generated from acquired data. In the frequency domain, obtained thermal data indicated the onset of regenerative machining chatter earlier and more effective than conventional force measurement by dynamometer.

Machining of Carbon Fiber Reinforced Plastics/Polymers: A Literature Review

“…Advanced experimental techniques are necessary to provide empirical information for the formulation and verification of the temperature-related cutting theories [80]. Recently, Werschmoeller [81] and Werschmoeller et al [82] developed a series of micro thin film embedded sensors (/i-TFESs) which can be located under the rake face and flank face of the tools in various materials (like PCBN or PCD) to measure in-situ temperature fields at the workpiece-tool interfaces. This technique can provide a plausible way to monitor thermal responses and evaluate temperature prediction theories in CFRP cutting as well.…”

Experimental investigation of cutting tool temperature during slot milling of AerMet 100 steel

“…An acquisition frequency of 20 Hz is set at the cutting speed of 1750 m/min. It is reported by Werschmoeller 19 that highly transient heat input with frequency of 100 Hz will become virtually indistinguishable from constant heat input with a distance of 1 mm or more, which is due to limited heat dissipation speed and heat pulse damping caused by the tool insert material.…”

An Investigation of Workpiece Temperature in Orthogonal Turn-Milling Compound Machining

“…4, shear velocity Vs is parallel to shear force, and chip flow velocity is collinear with friction on the rake face. The magnitude of Vs can be obtained from the velocity geometry relationship as v ( 14) cos <p; cos(0s -a " ) 4.3 Heat Intensity and Heat Partition Into Workpiece. The part of heat caused by orthogonal turn-mill machining transferring into the surroundings is so little that it is neglected in this model, namely, the workpiece surface is adiabatic boundary.…”

“…Agarwal and Venkateswara [13] raised an analytical model on unde formed chip thickness, predicating cutting force and energy in ceramic grinding. Werschmoeller et al [14] presented a novel approach for obtaining thermal data from hard turning by insertembedded thin film sensors. Shu et al [15] put forward a novel approach to measure and control cutting temperature in process through experimental and numerical modeling method.…”