Papers by Alok Singh chauhan
Materials Today: Proceedings, 2020
Turbine blade/vane castings for aero-engine applications are produced through the investment cast... more Turbine blade/vane castings for aero-engine applications are produced through the investment casting process. In order to increase the turbine entry temperature and also to reduce the weight of individual blades, ceramic cores are used in the investment casting process to generate complex internal cooling passages. The wall thickness of hollow blades produced are critical, as a minimum wall thickness of 0.5 mm must be maintained ensuring desired strength of the high speed rotating turbine blades. The dimensional deviations in the ceramic cores due to shrinkage & warpage must be quantified before designing the tooling for the Ceramic Injection moulding. In present study, an attempt is made to quantify the shrinkage and warpage during injection molding. The quality of ceramic cores depends on the injection parameters. Predicting the shrinkage and warpage associated with the ceramic injection process helps in avoiding costly and time consuming iterations involved in die design and development. The flow process during filling, packing and cooling stages and the effect of injection molding parameters such as holding time, injection pressure (packing pressure) and flow rate on shrinkage, warpage and Von-Mises stresses on green core is studied using Moldex3D injection molding flow software. In the present study, a Taguchi based partial factorial experiment for optimization of ceramic injection parameters for injection molding of ceramic core is presented. The effect of individual parameters and their interaction is also presented.
Materials Today: Proceedings, 2018
Abstract The dimensional and geometrical accuracy of wax patterns used in the investment casting ... more Abstract The dimensional and geometrical accuracy of wax patterns used in the investment casting process has a direct effect on the quality of the final casting. Wax patterns are produced by injecting wax in the die cavity. The quality of wax patterns depends on the injection parameters. The objective of the paper is to analyze the influence of various injection parameters on the dimensional deviations of the component. Predicting the shrinkage and warpage associated with the wax injection process helps in avoiding costly and time consuming iterations involved in die design and development. Simulation of wax injection in the die cavity provides insight in the flow process in terms of weld lines, air trap, drop in temperature and pressure during filling, packing and cooling stages of the process. The stresses developed in the component is estimated which determines the warpage in the component.
Materials Today: Proceedings, 2018
Abstract Gas Turbines in Aerospace applications operate at extreme conditions of temperatures and... more Abstract Gas Turbines in Aerospace applications operate at extreme conditions of temperatures and stresses. The Blade/Vane components of these turbines have sculpted, twisted and hollow aerofoil geometry made using Nickel based super alloys through the investment casting process. Hollow wax patterns produced with use of ceramic cores are the first input to the investment casting process. The quantification and prediction of dimensional deviations due to shrinkage & warpage, which are dependent on injection parameters, shape of part and gating system adopted, is mandatory to arrive at acceptable tooling and castings. The insight of flow pattern in the die cavity imparts knowledge of possible weld lines, air-trap, jetting etc. The gating system may be designed, based on simulation results, to minimise such defect. The effects of injection molding parameters such as holding time, packing pressure and melt temperature on shrinkage and warpage of green part using moldex3D software are studied in this paper
Materials Today: Proceedings, 2015
Selection and peer-review under responsibility of the conference committee members of the 4th Int... more Selection and peer-review under responsibility of the conference committee members of the 4th International conference on Materials Processing and Characterization.
The talk presented at 29th Annual General Meeting Of Materials Research Society Of India And Nati... more The talk presented at 29th Annual General Meeting Of Materials Research Society Of India And National Symposium On Advances In Functional And Exotic Materials.
LASER based inspection systems are widely used in precision manufacturing system in the recent ye... more LASER based inspection systems are widely used in precision manufacturing system in the recent years. LASER CMM in which a LASER probe attached to Co-ordinate measuring machine is capable rapid measurement of complex 3D sculptured geometry. These machines are capable of capturing large number of data points in the order of thousand of points per second with good accuracy. This inspection is non contact, suitable for fragile and soft components and it is faster and complete surface profile data available in least time. This paper describe various applications of LASER inspection for precision component like turbine blade wax pattern and ceramic core and also describes the development of land based power generation turbine blade through reverse engineering methodology. ©2017 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of Conference Committee Members of 5th International Conference of Materials Processing and Characterization (ICMPC 2016).
Journal of Materials Processing Technology
Gas Turbines in Aerospace applications operate at extreme conditions of temperatures and stresses... more Gas Turbines in Aerospace applications operate at extreme conditions of temperatures and stresses. The Blade/Vane components of these turbines have sculpted, twisted and hollow aerofoil geometry made using Nickel based super alloys through the investment casting process. Hollow wax patterns produced with use of ceramic cores are the first input to the investment casting process. The quantification and prediction of dimensional deviations due to shrinkage & warpage, which are dependent on injection parameters, shape of part and gating system adopted, is mandatory to arrive at acceptable tooling and castings. The insight of flow pattern in the die cavity imparts knowledge of possible weld lines, air-trap, jetting etc. The gating system may be designed, based on simulation results, to minimise such defect. The effects of injection molding parameters such as holding time, packing pressure and melt temperature on shrinkage and warpage of green part using moldex3D software are studied in ...
The dimensional and geometrical accuracy of wax patterns used in the investment casting process h... more The dimensional and geometrical accuracy of wax patterns used in the investment casting process has a direct effect on the quality of the final casting. Wax patterns are produced by injecting wax in the die cavity. The quality of wax patterns depends on the injection parameters. The objective of the paper is to analyze the influence of various injection parameters on the dimensional deviations of the component. Predicting the shrinkage and warpage associated with the wax injection process helps in avoiding costly and time consuming iterations involved in die design and development. Simulation of wax injection in the die cavity provides insight in the flow process in terms of weld lines, air trap, drop in temperature and pressure during filling, packing and cooling stages of the process. The stresses developed in the component is estimated which determines the warpage in the component.
Modern turbine engines for aerospace applications need precision investment cast components such ... more Modern turbine engines for aerospace applications need precision investment cast components such as integrally cast rotors and stators, for their hot end turbine stages. Traditionally, these turbines are used as starter engines. In recent times, such engines are also used for strategic missile applications. The rotor/stator castings consist of a central hub (shrouded in some designs) over which a number of aerofoil shaped blades are located. Since these components cannot be machined, investment casting is the only available route for manufacture and hence stringent dimensional aerospace quality has to be in-built in the casting process itself. In the process of investment casting, pattern generation by injection of wax into dedicated dies/moulds is the first critical
step. Traditional approach deals in producing individual blades with hub/shroud features through wax injection and assembly of a set of such injected patterns onto a dedicated and precisely manufactured fixture to wax-weld and generate an integral wax
pattern, a process known as the ‘segmental approach’. It is possible to design a single-injection die with retractable metallic
inserts in the case of untwisted blades of stator patterns without the shroud. Such an approach is also possible for twisted blades of rotors with highly complex design of inter-blade inserts and retraction mechanisms. DMRL has for long established methods and procedures for the above to successfully supply precision castings for various defence related projects. In recent times, urea based soluble insert approach has also been successfully applied to overcome the need to design and manufacture a precision assembly fixture, leading to substantial reduction in component development times. Present paper deals in length various approaches tried and established at DMRL to generate precision wax patterns for aerospace quality turbine rotors and stators. In addition to this, the importance of simulation in solving issues related to wax injection is also touched upon.
Ceramic cores are used as sacrificial inserts to generate intricate and complex hollow shapes in ... more Ceramic cores are used as sacrificial inserts to generate intricate and complex hollow shapes in components made of advanced
materials for aero-engine and aerospace applications. Development of tooling to precisely and accurately shape the ceramic core using
Ceramic Injection Moulding (CIM) method is of primary concern. To meet stringent dimensional requirements, the tool geometry has to be
precisely compensated for shrinkage and distortion phenomenon observed in the entire process of the component development. In advanced
aero-engine applications, the hot end components of the turbine stage consisting of blade/vane castings have extremely complex internal
geometry generated using the ceramic cores. This application of investment casting technology has been well established in DMRL. In a
recent effort, tooling for ceramic cores have been successfully developed to produce complex shaped rotors for space application using
powder metallurgy techniques. Present paper attempts to highlight issues related to tooling for ceramic cores for development of a near-net
shaped, Ni-based Superalloy Dual Property HIP Rotors.
In the process of investment casting of precision
blade/vane components for aero-engine applicati... more In the process of investment casting of precision
blade/vane components for aero-engine applications,
generation of a precison wax pattern is the first critical step. A
significant part of the dimensional deviations observed in the
casting can be attributed to the wax pattern. During the
process of generation of wax pattern through injection
moulding, two types of dimensional deviations occur, namely
shrinkage and warpage. Shrinkage deviations are predictable
to a an extent as they are predominantly an outcome of the
injection temperature, which is controllable. Warpage on the
other hand is difficult to predict as it depends on many other
factors of injection molding process. However, control of
distortion is critical in order to conform to the strict
dimensional tolerances of aerospace standards imposed on the
turbine blade/cane castings. Simulation based studies are
emerging as the preferred route for prediction of extent and
location of warpage in precision wax patterns. In the present
study, Moldex3D based simulation package has been utilized
to anlyze the effect of injection temperature, packing pressure,
cooling time and flow rate on the distortion behavior of a
stepped pattern. Two types of waxes with different rheological
properties have also been included to gauge the effect of
change in wax on the warpage. A full factorial design of
experiments has been configured and results of the analysis of
variance is presented.
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Papers by Alok Singh chauhan
step. Traditional approach deals in producing individual blades with hub/shroud features through wax injection and assembly of a set of such injected patterns onto a dedicated and precisely manufactured fixture to wax-weld and generate an integral wax
pattern, a process known as the ‘segmental approach’. It is possible to design a single-injection die with retractable metallic
inserts in the case of untwisted blades of stator patterns without the shroud. Such an approach is also possible for twisted blades of rotors with highly complex design of inter-blade inserts and retraction mechanisms. DMRL has for long established methods and procedures for the above to successfully supply precision castings for various defence related projects. In recent times, urea based soluble insert approach has also been successfully applied to overcome the need to design and manufacture a precision assembly fixture, leading to substantial reduction in component development times. Present paper deals in length various approaches tried and established at DMRL to generate precision wax patterns for aerospace quality turbine rotors and stators. In addition to this, the importance of simulation in solving issues related to wax injection is also touched upon.
materials for aero-engine and aerospace applications. Development of tooling to precisely and accurately shape the ceramic core using
Ceramic Injection Moulding (CIM) method is of primary concern. To meet stringent dimensional requirements, the tool geometry has to be
precisely compensated for shrinkage and distortion phenomenon observed in the entire process of the component development. In advanced
aero-engine applications, the hot end components of the turbine stage consisting of blade/vane castings have extremely complex internal
geometry generated using the ceramic cores. This application of investment casting technology has been well established in DMRL. In a
recent effort, tooling for ceramic cores have been successfully developed to produce complex shaped rotors for space application using
powder metallurgy techniques. Present paper attempts to highlight issues related to tooling for ceramic cores for development of a near-net
shaped, Ni-based Superalloy Dual Property HIP Rotors.
blade/vane components for aero-engine applications,
generation of a precison wax pattern is the first critical step. A
significant part of the dimensional deviations observed in the
casting can be attributed to the wax pattern. During the
process of generation of wax pattern through injection
moulding, two types of dimensional deviations occur, namely
shrinkage and warpage. Shrinkage deviations are predictable
to a an extent as they are predominantly an outcome of the
injection temperature, which is controllable. Warpage on the
other hand is difficult to predict as it depends on many other
factors of injection molding process. However, control of
distortion is critical in order to conform to the strict
dimensional tolerances of aerospace standards imposed on the
turbine blade/cane castings. Simulation based studies are
emerging as the preferred route for prediction of extent and
location of warpage in precision wax patterns. In the present
study, Moldex3D based simulation package has been utilized
to anlyze the effect of injection temperature, packing pressure,
cooling time and flow rate on the distortion behavior of a
stepped pattern. Two types of waxes with different rheological
properties have also been included to gauge the effect of
change in wax on the warpage. A full factorial design of
experiments has been configured and results of the analysis of
variance is presented.
step. Traditional approach deals in producing individual blades with hub/shroud features through wax injection and assembly of a set of such injected patterns onto a dedicated and precisely manufactured fixture to wax-weld and generate an integral wax
pattern, a process known as the ‘segmental approach’. It is possible to design a single-injection die with retractable metallic
inserts in the case of untwisted blades of stator patterns without the shroud. Such an approach is also possible for twisted blades of rotors with highly complex design of inter-blade inserts and retraction mechanisms. DMRL has for long established methods and procedures for the above to successfully supply precision castings for various defence related projects. In recent times, urea based soluble insert approach has also been successfully applied to overcome the need to design and manufacture a precision assembly fixture, leading to substantial reduction in component development times. Present paper deals in length various approaches tried and established at DMRL to generate precision wax patterns for aerospace quality turbine rotors and stators. In addition to this, the importance of simulation in solving issues related to wax injection is also touched upon.
materials for aero-engine and aerospace applications. Development of tooling to precisely and accurately shape the ceramic core using
Ceramic Injection Moulding (CIM) method is of primary concern. To meet stringent dimensional requirements, the tool geometry has to be
precisely compensated for shrinkage and distortion phenomenon observed in the entire process of the component development. In advanced
aero-engine applications, the hot end components of the turbine stage consisting of blade/vane castings have extremely complex internal
geometry generated using the ceramic cores. This application of investment casting technology has been well established in DMRL. In a
recent effort, tooling for ceramic cores have been successfully developed to produce complex shaped rotors for space application using
powder metallurgy techniques. Present paper attempts to highlight issues related to tooling for ceramic cores for development of a near-net
shaped, Ni-based Superalloy Dual Property HIP Rotors.
blade/vane components for aero-engine applications,
generation of a precison wax pattern is the first critical step. A
significant part of the dimensional deviations observed in the
casting can be attributed to the wax pattern. During the
process of generation of wax pattern through injection
moulding, two types of dimensional deviations occur, namely
shrinkage and warpage. Shrinkage deviations are predictable
to a an extent as they are predominantly an outcome of the
injection temperature, which is controllable. Warpage on the
other hand is difficult to predict as it depends on many other
factors of injection molding process. However, control of
distortion is critical in order to conform to the strict
dimensional tolerances of aerospace standards imposed on the
turbine blade/cane castings. Simulation based studies are
emerging as the preferred route for prediction of extent and
location of warpage in precision wax patterns. In the present
study, Moldex3D based simulation package has been utilized
to anlyze the effect of injection temperature, packing pressure,
cooling time and flow rate on the distortion behavior of a
stepped pattern. Two types of waxes with different rheological
properties have also been included to gauge the effect of
change in wax on the warpage. A full factorial design of
experiments has been configured and results of the analysis of
variance is presented.