Study of the Size Effect on Friction Conditions in Microextrusion—Part I: Microextrusion Experiments and Analysis

2006 ◽  
Vol 129 (4) ◽  
pp. 669-676 ◽  
Author(s):  
Neil Krishnan ◽  
Jian Cao ◽  
Kuniaki Dohda
Keyword(s):  
Size Effects ◽  
Circular Cross Section ◽  
High Strength ◽  
Analytical Models ◽  
Homogeneous Material ◽  
Experimental Setup ◽  
Extrusion Force ◽  
Frictional Behavior ◽  
Extrusion Dies ◽  
Metallic Parts

Microforming is a relatively new realm of manufacturing technology that addresses the issues involved in the fabrication of metallic microparts, i.e., metallic parts that have at least two characteristic dimensions in the sub-millimeter range. The recent trend towards miniaturization of products and technology has produced a strong demand for such metallic microparts with extremely small geometric features and high tolerances. Conventional forming technologies, such as extrusion, have encountered new challenges at the microscale due to the influence of “size effects” that tend to be predominant at this length scale. One of the factors that of interest is friction. The two companion papers investigate the frictional behavior and size effects observed during microextrusion in Part I and in a stored-energy Kolsky bar test in Part II. In this first paper, a novel experimental setup consisting of forming assembly and a loading stage has been developed to obtain the force-displacement response for the extrusion of pins made of brass (Cu∕Zn: 70∕30). This experimental setup is used to extrude pins with a circular cross section that have a final extruded diameter ranging from 1.33mm down to 570μm. The experimental results are then compared to finite-element simulations and analytical models to quantify the frictional behavior. It was found that the friction condition was nonuniform and showed a dependence on the dimensions (or size) of the micropin under the assumption of a homogeneous material deformation. Such assumption will be eliminated in Part II where the friction coefficient is more directly measured. Part I also investigates the validity of using high-strength/low-friction die coatings to improve the tribological characteristics observed in micro-extrusion. Three different extrusion dies coated with diamondlike carbon with silicon (DLC-Si), chromium nitride (CrN), and titanium nitride (TiN) were used in the microextrusion experiments. All the coatings worked satisfactorily in reducing the friction and, correspondingly, the extrusion force with the DLC-Si coating producing the best results.

Microforming: Study of Friction Conditions and the Impact of Low Friction/High-Strength Die Coatings on the Extrusion of Micropins

2005 ◽  
Author(s):  
Neil Krishnan ◽  
Jian Cao ◽  
Kuniaki Dohda
Keyword(s):  
Circular Cross Section ◽  
High Strength ◽  
Analytical Models ◽  
Experimental Setup ◽  
Extrusion Force ◽  
Low Friction ◽  
Frictional Behavior ◽  
Extrusion Dies ◽  
Metallic Parts ◽  
The Impact

Microforming is a relatively new realm of manufacturing technology that addresses the issues involved in the fabrication of metallic microparts, i.e., metallic parts that have at least two characteristic dimensions in the sub-millimeter range. The recent trend towards miniaturization of products and technology has produced a strong demand for such metallic microparts with extremely small geometric features and high tolerances. Conventional forming technologies, such as extrusion, have encountered new challenges at the micro-scale due to the influence of ‘size effects’ that tend to be predominant at this length scale. One of the factors that shows a strong influence is friction. This paper focuses on the frictional behavior observed at various sample sizes during micro-extrusion. A novel experimental setup consisting of forming assembly and a loading stage has been developed to obtain the force-displacement response for the extrusion of pins made of brass (Cu/Zn: 70/30). This experimental setup is used to extrude pins with a circular cross-section that have a final extruded diameter ranging from 1.33 mm down to 570 microns. The experimental results are then compared to finite-element simulations and analytical models to quantify the frictional behavior. It was found that the friction condition was non-uniform and showed a dependence on the dimensions (or size) of the micropin. The paper also investigates the validity of using high-strength/ low friction die coatings to improve the tribological characteristics observed in micro-extrusion. Three different extrusion dies coated with diamond-like carbon with silicon (DLC-Si), chromium nitride (CrN) and titanium nitride (TiN) were used in the micro-extrusion experiments. All the coatings worked satisfactorily in reducing the friction and correspondingly, the extrusion force with the DLC-Si coating producing the best results.

PYROTOOL A

Alloy Digest ◽  
1971 ◽  
Vol 20 (4) ◽  
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Surface Treatment ◽  
Tensile Properties ◽  
High Strength ◽  
Heat Treating ◽  
Good Ductility ◽  
Extrusion Dies ◽  
Temperature Performance

Abstract PYROTOOL A has been designed to display high strength and good ductility at temperatures up to 1200 F. It is used for high-temperature tooling, extrusion dies, liners, dummy blocks, forging dies, mandrels, holders, etc. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Fe-47. Producer or source: Carpenter.

PYROTOOL EX

Alloy Digest ◽  
1972 ◽  
Vol 21 (3) ◽  
Keyword(s):  
High Temperature ◽  
Base Alloy ◽  
High Strength ◽  
Heat Treating ◽  
Nickel Base Alloy ◽  
Extrusion Dies ◽  
Temperature Performance ◽  
Technology Corporation ◽  
Carpenter Technology Corporation ◽  
Nickel Base

Abstract PYROTOOL EX is an austenitic precipitation-hardenable nickel-base alloy with high strength in the range 1000 to 1500 F. When aged it produces a hardness of Rockwell C 40-44. Applications include high-temperature tooling, extrusion dies and dummy blocks. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Ni-170. Producer or source: Carpenter Technology Corporation.

PYROTOOL W

Alloy Digest ◽  
1971 ◽  
Vol 20 (2) ◽  
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Surface Treatment ◽  
High Strength ◽  
Heat Treating ◽  
Extrusion Dies ◽  
Temperature Performance ◽  
Technology Corporation ◽  
Carpenter Technology Corporation

Abstract PYROTOOL W has been designed to possess high strength and hardness at temperatures up to 1500 F (816 C). Applications include high-temperature tooling, extrusion dies, dummy blocks, rings, holders, forging dies and mandrels. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ni-161. Producer or source: Carpenter Technology Corporation.

Increased Productivity in Hot Aluminum Extrusion by Using Extrusion Dies with Inner Cooling Channels Manufactured by Rapid Tooling

2014 ◽  
Vol 611-612 ◽  
pp. 981-988 ◽  
Author(s):  
Ramona Hölker ◽  
Matthias Haase ◽  
Nooman Ben Khalifa ◽  
A. Erman Tekkaya
Keyword(s):  
Surface Defects ◽  
Experimental Investigations ◽  
Extrusion Force ◽  
Aluminum Extrusion ◽  
Thermally Induced ◽  
Manufacturing Method ◽  
Cooling Channels ◽  
Extrusion Dies ◽  
Exit Temperature ◽  
Tooling Technology

The influence of local inner die cooling on the heat balance in hot aluminum extrusion was investigated. For the manufacturing of the die with cooling channels close to the forming zone, the layer-laminated manufacturing method was applied. The new tooling technology was applied in order to decrease the profiles exit temperature and to avoid thermally induced surface defects with the aim to raise the productivity in hot aluminum extrusion processes. Numerical and experimental investigations revealed that, while maintaining the exit temperature of the extrudate, a distinct increase of the production speed up to 300% can be realized, while the extrusion force increases only slightly. An effect on the profiles microstructure was also detected. By applying die cooling, grain coarsening can be significantly limited or even be avoided.

scholarly journals Effect of Rise and Fall Time on Dwell Fatigue Behavior of a High Strength Titanium Alloy

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 914 ◽  
Author(s):  
Qingyuan Song ◽  
Yanqing Li ◽  
Lei Wang ◽  
Ruxu Huang ◽  
Chengqi Sun
Keyword(s):  
Titanium Alloy ◽  
Fatigue Life ◽  
Crack Initiation ◽  
Cross Section ◽  
Fatigue Behavior ◽  
Circular Cross Section ◽  
High Strength ◽  
Initiation Mechanism ◽  
Fall Time ◽  
Dwell Fatigue

Frequency is an important factor influencing the fatigue behavior. Regarding to the dwell fatigue, it corresponds to the effect of rise and fall time, which is also an important issue especially for the safety evaluation of structure parts under dwell fatigue loading, such as the engines of aircrafts and the pressure hulls of deep-sea submersibles. In this paper, the effect of rise and fall time (2 s, 20 s, 110 s, and 200 s) on the dwell fatigue behavior is investigated for a high strength titanium alloy Ti-6Al-2Sn-2Zr-3Mo-X with basket-weave microstructure. It is shown that the dwell fatigue life decreases with increasing the rise and fall time, which could be correlated by a linear relation in log–log scale for both the specimen with circular cross section and the specimen with square cross section. The rise and fall time has no influence on the crack initiation mechanism by the scanning electron microscope observation. The cracks initiate from the specimen surface and all the fracture surfaces present multiple crack initiation sites. Moreover, the facet characteristic is observed at some crack initiation sites for both the conventional fatigue and dwell fatigue tests. The paper also indicates that the dwell period of the peak stress reduces the fatigue life and the dwell fatigue life seems to be longer for the specimen with circular cross section than that of the specimen with square cross section.

scholarly journals Instrumentation for mechanical vibrations analysis in the time domain and frequency domain using the Arduino platform

2016 ◽  
Vol 38 (1) ◽  
Author(s):  
Marcus Varanis ◽  
Anderson Langone Silva ◽  
Pedro Henrique Ayres Brunetto ◽  
Rafael Ferreira Gregolin
Keyword(s):  
Signal Processing ◽  
Finite Elements ◽  
Time Domain ◽  
Good Accuracy ◽  
Low Cost ◽  
Analytical Models ◽  
Experimental Setup ◽  
Mechanical Vibrations ◽  
Python Language ◽  
The Time Domain

In this paper, we use the Arduino platform together with sensors as accelerometer, gyroscope and ultrasound, to measure vibrations in mechanical systems. The main objective is to assemble a signals acquisition system easy to handle, of low cost and good accuracy for teaching purposes. It is also used the Python language and its numerical libraries for signal processing. This paper proposes the study of vibrations of a beam, which is measured by position, velocity and acceleration. An experimental setup was implemented. The results obtained are compared with analytical models and computer simulations using finite elements. The results are in agreement with the literature.

Investigation of Size Effects on Process Models for Plane Strain Microbending

2006 ◽  
Author(s):  
Richard M. Onyancha ◽  
Brad L. Kinsey
Keyword(s):  
Size Effects ◽  
Strain Distribution ◽  
Past Research ◽  
Peak Force ◽  
Process Models ◽  
Analytical Models ◽  
Linear Strain ◽  
Bending Force ◽  
Bending Process ◽  
Individual Grains

Accurate process models provide vital information in the design of manufacturing processes. To characterize bending operations, analytical models have been developed and shown to predict the peak bending forces fairly accurately for sheets in the macro or mesoscale (i.e. sheets with a large number of grains through the thickness). However, whether these models also accurately predict bending forces for sheets in the microscale (i.e. sheets with approximately ten grains or less through the thickness) has not been evaluated. The present study is aimed at investigating the use of two such models from previous work with microscale bending data. In addition, using these previous models as a foundation, additional bending force models were developed to predict the bending force specifically for microscale bending operations. Data analysis showed that the process models from past research, which provide accurate results for macroscale bending, over predict the peak force required for bending microscale sheets. These process models assume a non-linear strain distribution through the thickness and a curved formed wall. The two models developed in this research provide accurate results for the microscale bending tests, however, they under predict the peak force for the macroscale bending operation. These developed process models assume a linear strain distribution through the thickness and a straight formed wall. The linear strain distribution is more appropriate for the microscale bending process as there are few grains through the thickness and the strain in individual grains varies linearly across the grain. The straight formed wall is more appropriate for the microscale bending process as there is not sufficient distance to warrant a curved formed wall assumption. These differences represent size effects for assumptions in the process models. The material used for these investigations was Brass (CuZn15). The sheets had between 2 and 50 grains through the thickness with grain sizes of between 10 μm and 71 μm.

Strain Enhanced High Strength Cu–Ag–Zr Conductors

2009 ◽  
Vol 633-634 ◽  
pp. 707-715 ◽  
Author(s):  
Julia Lyubimova ◽  
Jens Freudenberger ◽  
Alexandere Gaganov ◽  
Hansjörg Klauss ◽  
Ludwig Schultz
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
Phase Separation ◽  
Grain Growth ◽  
High Strength ◽  
Homogeneous Material ◽  
Growth Processes ◽  
Heat Treated ◽  
Different Temperatures ◽  
Zr Alloys

Recovery, recrystallisation and grain growth processes as well as the formation of a solid solution and the phase separation of a homogeneous material into a heterogeneous one are observed for Cu-Ag-Zr alloys heat-treated at different temperatures by means of mechanical, electrical and microstructural analyses. Heat treatments are shown to be an effective tool to enhance the strain to failure. If applied between several deformation steps the heat treatment causes an increase of both strain and strength limits.

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