Experimental Investigation of Hard Turning Mechanisms by PCBN Tooling Embedded Micro Thin Film Thermocouples

2012 ◽  
Author(s):  
Linwen Li ◽  
Bin Li ◽  
Xiaochun Li ◽  
Kornel F. Ehmann
Keyword(s):  
Thin Film ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Chip Formation ◽  
Hard Turning ◽  
Cutting Temperature ◽  
Temperature Distributions ◽  
Field Distributions ◽  
Thin Film Thermocouples ◽  
Cutting Zone

Temperature-distribution measurements in cutting tools during the machining process are extremely difficult and remain an unresolved problem. In this paper, cutting temperature distributions are measured by thin film thermocouples (TFTCs) embedded into Polycrystalline Cubic Boron Nitride (PCBN) cutting inserts in the immediate vicinity of the tool-chip interface. Using these measurements, steady and dynamic phenomena during hard turning as well as the chip morphology and formation process were analyzed based on the cutting temperature distributions in the insert. The relationship between the cutting temperature-field distributions in the PCBN insert and the segmented chip formation is analyzed using temperature-distribution mapping. It is shown that the temperature-distribution in the cutting zone depends on the shearing band distribution in the chip and the thermal transfer rate from the heat generation zone to the cutting tool. Furthermore, it became evident that the material flow stress and the shearing bands greatly affect not only the chip formation morphology but also the cutting temperature field distributions in the cutting zone of the cutting insert.

Finite Difference Modeling of Cutting Temperature in Machining of A6061-T6 Aluminum Alloy at Ultra High Cutting Speeds

2007 ◽  
Vol 329 ◽  
pp. 681-686 ◽  
Author(s):  
Toshiyuki Obikawa ◽  
Ali Basti ◽  
Jun Shinozuka
Keyword(s):  
Thin Film ◽  
Temperature Distribution ◽  
Finite Difference ◽  
Orthogonal Cutting ◽  
Cutting Temperature ◽  
Rake Face ◽  
Thin Film Thermocouples ◽  
Cutting Zone ◽  
The Finite Difference Method ◽  
Cutting Speeds

The finite difference method was applied to simulate temperature distribution in the workpiece, cutting zone and tool in the orthogonal cutting process with multilayer coated sintered alumina tools. The analysis was conducted under different cutting speeds, while experiments were carried out to measure temperatures in different positions of the tool rake face using tools with built-in thin film thermocouples developed by the authors. The temperature distribution calculated along the rake face was consistent with experimental data. This proved that the finite difference modeling developed can be applied to the prediction of cutting temperatures of aluminum alloys for a range of ultra high cutting speeds.

Experimental Investigation of Hard Turning Mechanisms by PCBN Tooling Embedded Micro Thin Film Thermocouples

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Linwen Li ◽  
Bin Li ◽  
Xiaochun Li ◽  
Kornel F. Ehmann
Keyword(s):  
Thin Film ◽  
Hard Turning ◽  
Cubic Boron Nitride ◽  
Cutting Tools ◽  
Cutting Temperature ◽  
Chip Morphology ◽  
Machining Process ◽  
Cutting Insert ◽  
Thin Film Thermocouples ◽  
Cutting Zone

Temperature-distribution measurements in cutting tools during the machining process are extremely difficult and remain an unresolved problem. In this paper, cutting temperature distributions were measured by thin film thermocouples (TFTCs) embedded into polycrystalline cubic boron nitride (PCBN) cutting inserts in the immediate vicinity of the tool-chip interface. The embedded TFTC array provides temperature measurements with a degree of spatial resolution (100 μm) and dynamic response (150 ns) that is not possible with currently employed methods due to the micro-scale junction size of the TFTCs. Using these measurements during hard turning, steady-state, dynamic, as well as chip morphology and formation process analyses were performed based on the cutting temperature and cutting force variations in the cutting zone. It has been shown that the temperature changes in the cutting zone depend on the shearing band location in the chip and the thermal transfer rate from the heat generation zone to the cutting tool. Furthermore, it became evident that the material flow stress and the shearing bands greatly affect not only the chip formation morphology but also the cutting temperature field distributions in the cutting zone of the cutting insert.

Assessment and Improvement of the Thermal Performance of a Polycarbonate Micro Continuous Flow Polymerase Chain Reactor (CFPCR)

2007 ◽  
Author(s):  
Pin-Chuan Chen ◽  
Michael W. Mitchell ◽  
Dimitris E. Nikitopoulos ◽  
Steven A. Soper ◽  
Michael C. Murphy
Keyword(s):  
Thin Film ◽  
Liquid Crystal ◽  
Temperature Distribution ◽  
Thermal Management ◽  
Continuous Flow ◽  
Infrared Camera ◽  
Amplification Efficiency ◽  
Temperature Zone ◽  
Temperature Distributions ◽  
Polymerase Chain

BioMEMS are compact devices that use microfabrication to miniaturize benchtop instrumentation. Due to the requirement for uniform temperature distributions over restricted areas, thermal isolation, and faster heating and cooling rates in a limited space, thermal management is a key to ensuring successful performance of BioMEMS devices. The continuous flow polymerase chain reactor (CFPCR) is a compact BioMEMS device that is used to amplify target DNA fragments using repeated thermal cycling. The temperature distribution on the backside of a micro CFPCR was measured using thermochromic liquid crystals and an infrared camera. In the liquid crystal experiment, the performance of a 5 mm thick polycarbonate micro CFPCR with thin film heaters attached directly to the bottom polycarbonate surface over each temperature zone was studied. Natural convection was used as a cooling mechanism. The temperature distribution in the renaturation zone was dependent on the positions of the feedback thermocouples in each zone. Three different thermocouple configurations were assessed and the liquid crystal images showed that a best case 3.86°C temperature difference across the zone, leading to a 20% amplification efficiency compared to a commercial thermal cycler [5]. The device was modified to improve the temperature distribution: a thinner substrate, 2 mm, reduced the thermal capacitance; grooves were micro-milled in the backside to isolate each temperature zone; and three separate copper heating stages, combining the thin film heaters with copper plates, applied uniform temperatures to each zone [10]. Infrared camera images showed that the temperature distributions were distinct and uniform with a ±0.3 °C variations in each temperature zone, improving amplification efficiency to 72%. Good thermal management for PCR amplification can’t only increase its reliability and yield efficiency, but also accelerate the entire analytical process.

The Temperature Field Around a Spherical Ridge or Trough in a Plane

1992 ◽  
Vol 114 (2) ◽  
pp. 317-325 ◽  
Author(s):  
J. Fransaer ◽  
J. R. Roos
Keyword(s):  
Heat Flux ◽  
Contact Angle ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Flux Distribution ◽  
Spherical Particles ◽  
Heat Flux Distribution ◽  
Conducting Plane ◽  
Temperature Distributions ◽  
Random Array

An analytical solution, which describes the temperature field around a single spherical particle partly embedded in a plane or around a trough making an arbitrary contact angle with a plane, is presented here. The temperature distributions for three cases are studied: the temperature distribution around a conducting bowl or trough, the temperature distribution around a non-conducting bowl or trough present in a conducting plane, and the temperature profile around a conducting bowl or trough conducting heat toward a sink at infinity. The normalized heat flux distribution on the plane and particle is presented. The various incremental resistances caused by a single and a dilute planar random array of truncated spherical particles are also derived.

Evaluation of Chip Morphology in Hard Turning Using Constitutive Models and Material Property Data

2006 ◽  
Vol 129 (1) ◽  
pp. 41-47 ◽  
Author(s):  
Gérard Poulachon ◽  
Alphonse L. Moisan ◽  
I. S. Jawahir
Keyword(s):  
Flow Stress ◽  
Chip Formation ◽  
Hard Turning ◽  
Constitutive Relations ◽  
Cutting Temperature ◽  
Mechanical Tests ◽  
Bearing Steel ◽  
Material Behavior ◽  
Shear Instability ◽  
Instability Criterion

Modeling of machining operations requires the use of constitutive relations which could represent as close as possible the material behavior in the primary and secondary zones. The knowledge of these behavior laws involves the use of different types of sophisticated mechanical tests which should provide with sufficient accuracy the material behavior for the relevant conditions of machining. In this paper, first, the flow stress of 100Cr6 (AISI 52100) bearing steel in its HV730 hardness state has been identified in order to assess the machinability in case of hard turning. With this, the dependence of the flow stress on strain, strain rate and temperature, which poses significant difficulty, is presented. Second, the material machinability is evaluated with a shear instability criterion, enabling the prediction of chip formation with or without the shear localization. Quick-stop tests have been carried out on the bearing steel treated at different hardness values showing the chip formation variation. Micro-hardness tests performed on these quick-stop test samples show the effects of cutting temperature. A greater understanding of applied machinability is gained through this precise study of work material physical properties and behavior.

PCBN Tool Wear Mechanism in Hard Turning Hardened Bearing Steel

2006 ◽  
Vol 315-316 ◽  
pp. 334-338 ◽  
Author(s):  
S.J. Dai ◽  
Dong Hui Wen ◽  
Ju Long Yuan
Keyword(s):  
Wear Mechanism ◽  
Hard Turning ◽  
Cutting Temperature ◽  
Tool Material ◽  
Bearing Steel ◽  
Workpiece Material ◽  
Pcbn Tool ◽  
Wear Pattern ◽  
Tool Wear Mechanism ◽  
Cutting Zone

The wear pattern and mechanism during continuous hard turning GCr15 hardened bearing steel with BZN8200 PCBN cutting tool was studied. Experimental results showed that the main wear pattern is crater wear in rake face and mechanical wear in flank face, the main wear mechanism is made-up with adhesive, oxidization and diffusive wear. The adhesive wear is generated by melt workpiece material flows with binder material of PCBN tool during initial cutting, oxidative wear is derived by cutting temperature and pressure of cutting zone when the flank wear increase after initial cutting, diffusive wear phenomenon is the absolute mechanism with the diffusive effect between workpiece and tool material in final cutting time.

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