Thermal Expansion of the Workpiece in Turning

1995 ◽  
Vol 117 (4) ◽  
pp. 542-550 ◽  
Author(s):  
D. A. Stephenson ◽  
M. R. Barone ◽  
G. F. Dargush
Keyword(s):  
Thermal Expansion ◽  
Heat Input ◽  
Hard Turning ◽  
Large Diameter ◽  
Heat Sources ◽  
Workpiece Material ◽  
Form Errors ◽  
Direct Measurements ◽  
Cutting Zone ◽  
Machining Operations

Thermal expansion of the part can be a significant source of dimensional and form errors in precision machining operations. This paper describes a method for calculating the thermal expansion of an axisymmetric workpiece. The analysis is based on a commercially available boundary element code modified to properly represent concentrated moving heat sources such as those produced in machining. The inputs required are the amount of heat entering the part from the cutting zone and the thermal properties of the workpiece material. Calculations are compared with direct measurements of expansion from tests on large diameter 2024 aluminum sleeves. The agreement between calculated and measured values is generally reasonable, although calculated expansions are consistently smaller than measured expansions. This error is probably due to errors in estimating the heat input to the part, and particularly the neglect of flank friction in heat input calculations. Sample calculations for hard turning of a wheel spindle show that expansions can approach tolerances on critical surfaces. Based on sample calculations, thermal expansion is likely to be significant when hard turning parts with tolerances on the order of 0.01 mm. For these applications, critical surfaces should be machined first, before cuts on other sections heat the part, and gaging should be carried out only after the part has cooled.

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.

Evaluation of Cooling Potential and Tool Life in Turning Using Metalworking Fluids Delivered in Supercritical Carbon Dioxide

2009 ◽  
Author(s):  
Andres F. Clarens ◽  
Ye-Eun Park ◽  
Jacob Temme ◽  
Kim Hayes ◽  
Fu Zhao ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Tool Wear ◽  
Tool Life ◽  
Heat Removal ◽  
Minimum Quantity Lubrication ◽  
Metalworking Fluids ◽  
Compacted Graphite ◽  
Lower Viscosity ◽  
Cutting Zone ◽  
Machining Operations

Carbon Dioxide is an industrial byproduct that has been proposed as an alternative metalworking fluid (MWF) carrier with lower environmental impacts and better cooling potential than existing MWFs. This paper investigates the heat removal and tool life effects of rapidly expanding supercritical CO2 (scCO2)-based MWFs relative to MWFs delivered as a flood of semi-synthetic emulsion or as minimum quantity lubrication (MQL) sprays. When cutting both compacted graphite iron (CGI) and titanium, tool wear was most effectively controlled using the scCO2-based MWF compared with the other MWFs. Analysis in this paper suggests that the performance benefit imparted by rapidly expanding scCO2 appears to be related to both the cooling potential and penetration of the sprays into the cutting zone. High-pressure gas sprays have lower viscosity and higher velocity than conventional MWFs. An experiment in which the spray direction was varied clearly demonstrated the importance of spray penetration in tool wear suppression. The type of gas spray is also a significant factor in tool wear suppression. For instance, a spray of N2 delivered under similar conditions to CO2 effectively reduced tool wear relative to water based fluids, but not as much as CO2. This result is particularly relevant for MQL sprays which are shown to not cool nearly as effectively as scCO2 MWFs. These results inform development of scCO2-based MWFs in other machining operations, and provide insight into the optimization of scCO2 MWF delivery.

scholarly journals Optimisation of EDM Parameters for Cryogenically Treated EN31 Steel with Copper Tool

2021 ◽  
pp. 204-229
Author(s):  
Dillen Henry C ◽  
Goyal Sai Y ◽  
Mr. D. Sakthivel
Keyword(s):  
Removal Rate ◽  
Cryogenic Treatment ◽  
Tool Geometry ◽  
Hard Material ◽  
Workpiece Material ◽  
Heat Treated ◽  
Machining Operations ◽  
Heat Resistant Steels ◽  
Pulse On Time ◽  
Pulse Off Time

EDM has been replacing drilling, milling, grinding, and other traditional machining operations and is now a well-established machining option in many manufacturing industries throughout the world and is capable of machining geometrically complex or hard material components, that are precise and difficult-to-machine such as heat-treated tool steels, composites, superalloys, ceramics, carbides, heat resistant steels, etc. During machining done over EDM machine, with the workpiece, even the tool wears out. This tool wear is not desired as it changes the tool geometry. To overcome this hurdle, cryogenic treatment is carried out for workpiece material before machining. This report presents the optimization of EDM process parameters such as pulse on-time (Ton), pulse off-time (Toff), and Current (I) to obtain the greatest material removal rate (MRR) and less surface roughness (Ra) of EN31 steel with copper as the working electrode for machining.

scholarly journals Performance Evaluation of MQL Parameters Using Al2O3 and MoS2 Nanofluids in Hard Turning 90CrSi Steel

Lubricants ◽  
2019 ◽  
Vol 7 (5) ◽  
pp. 40 ◽  
Author(s):  
Tran Minh Duc ◽  
Tran The Long ◽  
Tran Quyet Chien
Keyword(s):  
Hard Turning ◽  
Cutting Performance ◽  
Hard Machining ◽  
High Productivity ◽  
Good Surface ◽  
Complex Part ◽  
Cutting Zone ◽  
Grinding Operations ◽  
Coated Carbide ◽  
Carbide Inserts

Hard machining has gained much attention to be an alternative solution for many traditional finish grinding operations due to high productivity, ease to adapt to complex part contours, the elimination of cutting fluids, good surface quality, and the reduction of machine tool investment. However, the enormous amount of heat generated from the cutting zone always requires the high-grade inserts and limits the cutting conditions. The MQL technique with nanofluids assisted for hard machining helps to improve the cutting performance while ensuring environmentally friendly characteristics. This paper focuses on the development of MQL technique by adding Al2O3 and MoS2 nanoparticles to the base fluids (soybean oil and water-based emulsion) for the hard turning of 90CrSi steel (60÷62 HRC). The analysis of variance (ANOVA) is used to evaluate the performance of MQL parameters in terms of cutting forces and surface roughness. The study reveals that a better performance of coated carbide inserts is observed by using MQL with Al2O3 and MoS2 nanofluids. In addition, the fluid type, nanoparticles and nanoparticle concentration have a strong effect on cutting performance. The interaction influence among the investigated variables is also studied in order to provide the technical guides for further studies using Al2O3 and MoS2 nanofluids.

scholarly journals Computer Application for Simulation of Temperature Distribution Inside the Room

2018 ◽  
Vol 210 ◽  
pp. 04036
Author(s):  
Hana Charvátová ◽  
Martin Zálešák
Keyword(s):  
Spatial Distribution ◽  
User Interface ◽  
Temperature Distribution ◽  
Heat Input ◽  
Computer Application ◽  
Comsol Multiphysics ◽  
Heat Sources ◽  
Cyclic Heating ◽  
Heating And Cooling ◽  
Computer Testing

The paper deals with computer testing of the temperature distribution in buildings by using COMSOL Multiphysics software. It is devoted to a description of a computer application created in the Application Builder user interface for simulation of the temperature distribution in a room heated by two heat sources. The application allows you to change geometric dimensions of all elements of the studied model and their spatial distribution, as well as a choice of physical properties needed to access the distribution of temperature in the room depending on the ambient temperature and the heat input of the considered sources. Main functions of the application are presented by simulation of cyclic heating and cooling of the tested room.

scholarly journals Effect of Si in Workpiece Material on Tool Wear in Hard Turning

2018 ◽  
Vol 104 (4) ◽  
pp. 208-217
Author(s):  
Tatsuya Iwasaki ◽  
Toshiharu Aiso ◽  
Koji Watari
Keyword(s):  
Tool Wear ◽  
Hard Turning ◽  
Workpiece Material

Effect of the FCAW Welding Process and Post Weld Heat Treatment on the Properties and Microstructure of the Weld Joints of Heat Treated 4330V Steel

2015 ◽  
Vol 809-810 ◽  
pp. 437-442
Author(s):  
Jacek Górka ◽  
Michał Miłoszewski
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Weld Metal ◽  
Heat Input ◽  
Large Diameter ◽  
Welding Process ◽  
Post Weld Heat Treatment ◽  
High Toughness ◽  
Interpass Temperature ◽  
Weld Heat

4330V is a high strength, high toughness, heat treatable low alloy steel for application in the oil, gas and aerospace industries. It is typically used for large diameter drilling parts where high toughness and strength are required. The research describes the effect of preheat temperature, interpass temperature, heat input, and post weld heat treatment on strength, hardness, toughness, and changes to microstructure in the weld joint. Welding with the lower heat input and no post weld heat treatment resulted in optimal mechanical properties in the weld metal. Austempering at 400 °C resulted in optimal mechanical properties in the HAZ. Increasing preheat and interpass temperature from 340 °C to 420 °C did not improve Charpy V-notch values or ultimate tensile strength in the weld metal or heat affected zones. The higher temperature increased the width of the heat affected zone. Austempering at 400 °C reduced HAZ hardness to a level comparable to the base metal. Both tempering and austempering at 400 °C for 10 hours reduced toughness in the weld metal.

Thermal Aspects of the Split-Beam Laser Welding Concept

1991 ◽  
Vol 113 (2) ◽  
pp. 215-221 ◽  
Author(s):  
Elijah Kannatey-Asibu
Keyword(s):  
Heat Source ◽  
Laser Welding ◽  
Cooling Rate ◽  
Weld Pool ◽  
Heat Input ◽  
Total Heat ◽  
Source Process ◽  
Heat Sources ◽  
Single Source ◽  
Beam Laser

The high cooling rates normally encountered in the application of high intensity welding processes such as laser beam welding is often detrimental to the weldment, especially for high hardenability steels. To minimize this effect, the split-beam laser welding concept is proposed and analyzed. The analysis shows that even when the intensity of the single heat source is the same as the intensity of each of the dual heat sources, the resulting cooling rate at any specific temperature is lower for the dual source process than the single source process. For example, for mild steel, the cooling rate at a point 25 mm behind the heat source (where the temperature is 1364°C) was determined to be 382°C/s for the single source system, while that for a point 40 mm behind the major source (where the temperature is 1377°C) was determined to be 206°C/s for the dual heat source system. When the heat inputs for the dual system are reduced such that the total heat input is equal to that of the single source system, the resulting temperature rise is lower at all points of the weldment for the dual system. That also means a smaller weld pool size and heat affected zone. To maintain the same weld pool size and penetration as for the single heat source system then requires an increased total heat input for the dual heat source system, with the additional input depending on the spacing between the two heat sources.

Cutter-Workpiece Engagement Calculations by Parallel Slicing for Five-Axis Flank Milling of Jet Engine Impellers

2007 ◽  
Author(s):  
W. Ferry ◽  
D. Yip-Hoi
Keyword(s):  
Application Programming Interface ◽  
Solid Modeling ◽  
Flank Milling ◽  
Workpiece Material ◽  
Jet Engine ◽  
End Mills ◽  
Slicing Method ◽  
Machining Operations ◽  
Intersection Curves ◽  
Five Axis

Cutter-workpiece engagement maps, or cutting flute entry/exit locations as a function of height, are a requirement for prediction of cutting-forces on the tool and workpiece in machining operations such as milling. This paper presents a new method of calculating tool-part intersection maps for five-axis flank milling of jet engine impellers with tapered ball-end mills. It is called the parallel slicing method (PSM) and is a semi-discrete solid modeling technique written in C++ using the ACIS B-rep solid modeling environment. Although it is tailored towards five-axis flank milling, it can also be applied to both planar and multi-axis milling processes. The tool swept envelope is generated and intersected with the workpiece to obtain the removal volume. The removal volume is then sliced into a number of parallel planes along a given axis and the intersection curves with the tool and each plane are determined analytically. The swept area between the intersection curves of successive tool moves is calculated by solving for the area enclosed by the tangent lines. This area is removed from the workpiece material, which deletes the material cut between tool moves. Finally, the intersection curves are compared with the planar slices of the updated part, which results in a series of arcs. The end points of these arcs are joined with linear segments to form the engagement polygon which is used to calculate the engagement maps. Using this method, cutter-workpiece engagement maps are generated for a five-axis flank milling toolpath on a prototype integrally bladed rotor (IBR) with a tapered ball-end mill. These maps are compared with those obtained from a benchmark cutter-workpiece engagement calculation method – the Manufacturing Automation Laboratory’s Virtual Machining Interface (MAL-VMI). The MAL-VMI uses an application programming interface (API) in a commercial NC verification software package to obtain cutter-part intersections through a fast, z-buffer technique. Overall, the parallel slicing method appears to obtain more accurate engagement zones than those given by the MAL-VMI, although the calculation time is longer.

Comparison on welding mode characteristics of arc heat source for heat input control in hybrid welding of aluminum alloy

2015 ◽  
Vol 29 (06n07) ◽  
pp. 1540016
Author(s):  
Moo-Keun Song ◽  
Jong-Do Kim ◽  
Jae-Hwan Oh
Keyword(s):  
Experimental Study ◽  
Aluminum Alloy ◽  
Heat Source ◽  
Laser Welding ◽  
Heat Input ◽  
Heat Sources ◽  
Hybrid Welding ◽  
Input Control ◽  
Mode Characteristics ◽  
Pulsed Arc

Presently in shipbuilding, transportation and aerospace industries, the potential to apply welding using laser and laser-arc hybrid heat sources is widely under research. This study has the purpose of comparing the weldability depending on the arc mode by varying the welding modes of arc heat sources in applying laser-arc hybrid welding to aluminum alloy and of implementing efficient hybrid welding while controlling heat input. In the experimental study, we found that hybrid welding using CMT mode produced deeper penetration and sounder bead surface than those characteristics produced during only laser welding, with less heat input compared to that required in pulsed arc mode.

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