The Experts below are selected from a list of 57111 Experts worldwide ranked by ideXlab platform
Sayyad Zahid Qamar - One of the best experts on this subject based on the ideXlab platform.
-
effect of Shape Complexity on ram pressure and metal flow in aluminum extrusion
JOM, 2019Co-Authors: Sayyad Zahid Qamar, Josiah Cherian Chekotu, Sayyad Basim QamarAbstract:Product output and quality are directly affected by metal flow through the extrusion die. The current paper investigates the effect of profile Complexity on extrusion pressure, metal flow, and product defects. Cold extrusion experiments were performed on three solid profiles of different complexities. Simulations were carried out for these three Shapes using the commercial finite element package DEFORM-3D. After verifying against experimental results, numerical work was extended to six more profiles of varying Complexity. It was found that profiles of higher Complexity usually result in more inhomogeneous metal flow, require larger extrusion forces, and are more susceptible to product defects. Current Complexity definitions need to be improved for consistent ranking of die profiles. Factors such as extrusion ratio and die profile symmetry may also play a significant role in the distortion of metal flow through an extrusion die. These findings can be of direct utility in extrusion die design improvement and reduction of extrusion defects related to metal flow.
-
Shape Complexity in Metal Extrusion: Definitions, Classification, and Applications
Arabian Journal for Science and Engineering, 2019Co-Authors: Sayyad Zahid Qamar, Josiah Cherian Chekotu, Majid Al-maharbi, Khurshid AlamAbstract:One of the most important factors that affect quality and productivity in metal extrusion is Shape Complexity. It is an estimation of how complex an extruded profile (or die cavity) is. It has direct bearing on equipment selection, metal flow, die and tooling design, and critical process parameters. In turn, profile Complexity has major impact on die life, energy consumption, cost of manufacturing, material properties, etc. Without proper quantification of Shape Complexity, it is difficult to predict maximum extrusion pressure needed or to optimize die/tooling or process parameters for improved process efficiency and product quality. The first part of the current paper presents a general classification scheme for extrusion profiles and covers the different definitions and their origins. The later part discusses some applications of Shape Complexity, such as pressure prediction; evaluation of stress, strain etc.; die design and optimization; product defects; prediction of container and exit temperature; friction and wear in complex dies; failure and life estimation of dies and tools; estimation of manufacturability and cost; and novel extrusion methods for complex profiles. The review concludes by pointing out areas where possible future research can be done. As no comprehensive review of this very important issue is available in the published literature, this paper can be very useful for researchers, academicians, and practitioners in the area of metal extrusion.
-
Shape Complexity metal flow and dead metal zone in cold extrusion
Materials and Manufacturing Processes, 2010Co-Authors: Sayyad Zahid QamarAbstract:Nonhomogeneous metal flow through an extrusion die can directly affect product quality, productivity, and die life. The Complexity of a die profile is an indicator of how difficult it is to extrude the profile. Some investigations about the effect of die Complexity on extrusion pressure, product quality, and die life can be found in the published literature. However, the effect of profile Complexity on metal flow through the extrusion die has not been explored much. Such a study can directly contribute toward die design improvement and reduction of extrusion defects related to metal flow. This article investigates the effect of Shape Complexity on the dead metal zone (DMZ) and metal flow through cold extrusion experiments and finite element simulations on some solid profiles. Experiments were performed using flat-face dies of different complexities and different billet materials. 2D and 3D finite element simulations were carried out. One significant conclusion is that currently existing definitions of ext...
-
A new definition of Shape Complexity for metal extrusion
Journal of Materials Processing Technology, 2004Co-Authors: Sayyad Zahid Qamar, A F M Arif, A K SheikhAbstract:Abstract According to a basic definition, Complexity index for a given die profile is the ratio of the pressure required to extrude the profile relative to the extrusion pressure for a round cross-section of the same area. However, both intuitively and by definition, Complexity index is a function of geometry only. Various researchers and experimenters have coined different definitions for Shape Complexity of extrusion dies, based solely on geometrical parameters. The simplest definition depicts Complexity index as the ratio of profile perimeter to profile cross-sectional area. Other definitions are in terms of ratios of perimeter to weight, circumscribing circle diameter to minimum wall thickness, profile perimeter and equivalent circular perimeter, etc. Unfortunately, these definitions do not yield a consistent ranking of die profiles in terms of Shape Complexity. Moreover, the extrusion pressure predicted by these definitions often gives widely fluctuating values. The current paper aims at a new and more consistent definition of Complexity for extrusion profiles. All extrusion runs for the study have been carried out in collaboration with a local commercial extrusion facility (hot extrusion of structural aluminum). A total of 27 different dies are used, profile Complexity ranging from simple solids and hollows to quite complex ones. Die material (heat treated and surface hardened H-13 steel) and billet material (Al-6063) is the same for all experiments. Various runs at a ram speed of 3.8±0.1 mm/s have been carried out for 15 different die profiles, while another set of 12 profiles are extruded at 3.2±0.1 mm/s speed. After running a variety of regression runs, using various exponential, logarithmic and power law formats, the best-suited model for die Complexity has been determined to be of the form C=α+β P s P 0 γ , where Ps and P0 are the perimeters of the actual profile section and an equivalent circular section of equal area, respectively. The constants α, β and γ are determined statistically by regression of experimental hot extrusion data obtained for a variety of die complexities and somewhat different operating conditions. In comparison with the existing definitions, the curve that follows the reference Complexity curve (ratio of actual to circular-area pressure) most closely is that for the new definition.
A K Sheikh - One of the best experts on this subject based on the ideXlab platform.
-
defining Shape Complexity of extrusion dies a reliabilistic view
Materials and Manufacturing Processes, 2007Co-Authors: Z Qamar, A K Sheikh, A F M Arif, Tasneem PervezAbstract:Complexity of the profile being extruded plays a critical role in die design, die reliability, process aberrations, and product defects. Engineering common sense dictates that a more complex die should require a larger amount of extrusion force or pressure. This has been experimentally substantiated by the authors in a recent study. According to a basic definition, therefore, extrusion Shape Complexity is the ratio of the pressure required to extrude a complex profile to the pressure required for a solid circular profile of the same area. Most of the Complexity definitions reported in published literature are based on this interrelationship between extrusion pressure and profile Complexity. From a die reliability viewpoint, a complex profile is more difficult to extrude than a simple one, and it generates more stresses in the die. It should therefore lead to an earlier die failure. Another study by the authors confirms that the working life of hot extrusion dies is definitely affected by profile complexit...
-
defining Shape Complexity of extrusion dies a reliabilistic view
Materials and Manufacturing Processes, 2007Co-Authors: Z Qamar, A K Sheikh, A F M Arif, Tasneem PervezAbstract:Complexity of the profile being extruded plays a critical role in die design, die reliability, process aberrations, and product defects. Engineering common sense dictates that a more complex die should require a larger amount of extrusion force or pressure. This has been experimentally substantiated by the authors in a recent study. According to a basic definition, therefore, extrusion Shape Complexity is the ratio of the pressure required to extrude a complex profile to the pressure required for a solid circular profile of the same area. Most of the Complexity definitions reported in published literature are based on this interrelationship between extrusion pressure and profile Complexity. From a die reliability viewpoint, a complex profile is more difficult to extrude than a simple one, and it generates more stresses in the die. It should therefore lead to an earlier die failure. Another study by the authors confirms that the working life of hot extrusion dies is definitely affected by profile complexit...
-
A new definition of Shape Complexity for metal extrusion
Journal of Materials Processing Technology, 2004Co-Authors: Sayyad Zahid Qamar, A F M Arif, A K SheikhAbstract:Abstract According to a basic definition, Complexity index for a given die profile is the ratio of the pressure required to extrude the profile relative to the extrusion pressure for a round cross-section of the same area. However, both intuitively and by definition, Complexity index is a function of geometry only. Various researchers and experimenters have coined different definitions for Shape Complexity of extrusion dies, based solely on geometrical parameters. The simplest definition depicts Complexity index as the ratio of profile perimeter to profile cross-sectional area. Other definitions are in terms of ratios of perimeter to weight, circumscribing circle diameter to minimum wall thickness, profile perimeter and equivalent circular perimeter, etc. Unfortunately, these definitions do not yield a consistent ranking of die profiles in terms of Shape Complexity. Moreover, the extrusion pressure predicted by these definitions often gives widely fluctuating values. The current paper aims at a new and more consistent definition of Complexity for extrusion profiles. All extrusion runs for the study have been carried out in collaboration with a local commercial extrusion facility (hot extrusion of structural aluminum). A total of 27 different dies are used, profile Complexity ranging from simple solids and hollows to quite complex ones. Die material (heat treated and surface hardened H-13 steel) and billet material (Al-6063) is the same for all experiments. Various runs at a ram speed of 3.8±0.1 mm/s have been carried out for 15 different die profiles, while another set of 12 profiles are extruded at 3.2±0.1 mm/s speed. After running a variety of regression runs, using various exponential, logarithmic and power law formats, the best-suited model for die Complexity has been determined to be of the form C=α+β P s P 0 γ , where Ps and P0 are the perimeters of the actual profile section and an equivalent circular section of equal area, respectively. The constants α, β and γ are determined statistically by regression of experimental hot extrusion data obtained for a variety of die complexities and somewhat different operating conditions. In comparison with the existing definitions, the curve that follows the reference Complexity curve (ratio of actual to circular-area pressure) most closely is that for the new definition.
B Tomov - One of the best experts on this subject based on the ideXlab platform.
-
a new Shape Complexity factor
Journal of Materials Processing Technology, 1999Co-Authors: B TomovAbstract:Abstract In conventional closed-die forging process design the engineer must determine the required number of stages, which for forging parts of revolution could be from one to three or even more for the most complicated Shapes. Bearing in mind that the direct transforming of the billet to a final forging Shape is possible only in some very rare cases when mass M is very small (M ϕH, where K1 describes the amount of the transformed volume during two arbitrary stages of forging and ϕH is the logarithmic height strain. The criterion is checked for some examples using FEM analysis for calculating the work done. It is found that the new Shape Complexity factor reduce the number of forging steps.
Ramana V Grandhi - One of the best experts on this subject based on the ideXlab platform.
-
forging preform design with Shape Complexity control in simulating backward deformation
International Journal of Machine Tools & Manufacture, 1995Co-Authors: Guoqun Zhao, Ed Wright, Ramana V GrandhiAbstract:Abstract This paper presents a preform design method which employs an alternative boundary node release criterion in the finite element simulation of backward deformation of forging processes. The method makes use of the Shape Complexity factor which provides an effective measure of forging difficulty. The objective is to release die contacting nodes in a sequence which will minimize the geometric Complexity throughout the backward deformation simulation. This is done by calculating the effect of releasing each of a select group of boundary element nodes at each finite element solution step. The particular detached node which results in the minimum Shape Complexity factor will be released for the current step. This process continues for each backward step until the last few nodes remain in contact. This design method is demonstrated through the simulated forging of an integrated blade and rotor turbine disk blank. A preform Shape developed by this method is compared with an empirically designed preform. Performance parameters for comparison include die fill, flash volume, effective strain variance, frictional power and die load. Comparing the results of the forward simulations indicates improved performance of the preform design using FEM based backward deformation method over that of the empirical design.
A F M Arif - One of the best experts on this subject based on the ideXlab platform.
-
defining Shape Complexity of extrusion dies a reliabilistic view
Materials and Manufacturing Processes, 2007Co-Authors: Z Qamar, A K Sheikh, A F M Arif, Tasneem PervezAbstract:Complexity of the profile being extruded plays a critical role in die design, die reliability, process aberrations, and product defects. Engineering common sense dictates that a more complex die should require a larger amount of extrusion force or pressure. This has been experimentally substantiated by the authors in a recent study. According to a basic definition, therefore, extrusion Shape Complexity is the ratio of the pressure required to extrude a complex profile to the pressure required for a solid circular profile of the same area. Most of the Complexity definitions reported in published literature are based on this interrelationship between extrusion pressure and profile Complexity. From a die reliability viewpoint, a complex profile is more difficult to extrude than a simple one, and it generates more stresses in the die. It should therefore lead to an earlier die failure. Another study by the authors confirms that the working life of hot extrusion dies is definitely affected by profile complexit...
-
defining Shape Complexity of extrusion dies a reliabilistic view
Materials and Manufacturing Processes, 2007Co-Authors: Z Qamar, A K Sheikh, A F M Arif, Tasneem PervezAbstract:Complexity of the profile being extruded plays a critical role in die design, die reliability, process aberrations, and product defects. Engineering common sense dictates that a more complex die should require a larger amount of extrusion force or pressure. This has been experimentally substantiated by the authors in a recent study. According to a basic definition, therefore, extrusion Shape Complexity is the ratio of the pressure required to extrude a complex profile to the pressure required for a solid circular profile of the same area. Most of the Complexity definitions reported in published literature are based on this interrelationship between extrusion pressure and profile Complexity. From a die reliability viewpoint, a complex profile is more difficult to extrude than a simple one, and it generates more stresses in the die. It should therefore lead to an earlier die failure. Another study by the authors confirms that the working life of hot extrusion dies is definitely affected by profile complexit...
-
A new definition of Shape Complexity for metal extrusion
Journal of Materials Processing Technology, 2004Co-Authors: Sayyad Zahid Qamar, A F M Arif, A K SheikhAbstract:Abstract According to a basic definition, Complexity index for a given die profile is the ratio of the pressure required to extrude the profile relative to the extrusion pressure for a round cross-section of the same area. However, both intuitively and by definition, Complexity index is a function of geometry only. Various researchers and experimenters have coined different definitions for Shape Complexity of extrusion dies, based solely on geometrical parameters. The simplest definition depicts Complexity index as the ratio of profile perimeter to profile cross-sectional area. Other definitions are in terms of ratios of perimeter to weight, circumscribing circle diameter to minimum wall thickness, profile perimeter and equivalent circular perimeter, etc. Unfortunately, these definitions do not yield a consistent ranking of die profiles in terms of Shape Complexity. Moreover, the extrusion pressure predicted by these definitions often gives widely fluctuating values. The current paper aims at a new and more consistent definition of Complexity for extrusion profiles. All extrusion runs for the study have been carried out in collaboration with a local commercial extrusion facility (hot extrusion of structural aluminum). A total of 27 different dies are used, profile Complexity ranging from simple solids and hollows to quite complex ones. Die material (heat treated and surface hardened H-13 steel) and billet material (Al-6063) is the same for all experiments. Various runs at a ram speed of 3.8±0.1 mm/s have been carried out for 15 different die profiles, while another set of 12 profiles are extruded at 3.2±0.1 mm/s speed. After running a variety of regression runs, using various exponential, logarithmic and power law formats, the best-suited model for die Complexity has been determined to be of the form C=α+β P s P 0 γ , where Ps and P0 are the perimeters of the actual profile section and an equivalent circular section of equal area, respectively. The constants α, β and γ are determined statistically by regression of experimental hot extrusion data obtained for a variety of die complexities and somewhat different operating conditions. In comparison with the existing definitions, the curve that follows the reference Complexity curve (ratio of actual to circular-area pressure) most closely is that for the new definition.