Manufacturing Technology Today

S. Vijay ¹, J. L. Lalitha ¹, M. V. Rao ¹, A. Gopala Krishna ²

Affiliations
1 Mechanical Engg. Dept., Bapatla Engg. College, Bapatla, IN
2 Dept. of Mechanical Engg., JNTU, Kakinada, IN

Abstract

The emerging technology in manufacturing is Rapid Prototyping, by which one can fabricate the functional testing parts within less time. Rapid Prototyping (RP) includes different techniques viz., Stereolithography (SLA), Selective Laser Sintering (SLS), Fused Deposition Modeling (FDM), 3D Printing etc., In some RP processes, the extended portion of the part needs the support material. The support materials differ from part material, which is useful only for supporting purpose. After fabricating the parts the support material has to be discarded from the part. As per the cost criteria, the cost of the support materials ranges between 30-40% of the total cost depending on the geometries. While fabricating the part, the support material has to sustain the weight of the extended parts and its forces. The thermal stresses induced in the support material due to difference in temperatures of part and support material while solidifying process should also be taken into consideration. The paper concentrates on the volume reduction of the support material for basic geometries without losing the functional requirements of the support material. Finite Element Method has been applied for stresses and thermal analysis. The values thus found conclude that there is a possibility to reduce the volume of the support material for about 10-15% depending on geometry of the part and thereby reduces the cost of fabrication.

Keywords

Support Material, Rapid Prototyping, Volume Reduction, Basic Geometries.

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A. Gopala Krishna ¹

Affiliations
1 Dept. of Mechanical Engg., J. N. T. University, College of Engineering, Kakinada-533003, Andhra Pradesh, IN

Abstract

The selection of machining parameters in any machining process significantly affects production rate:quality and cost of a component. The present work involves the application of a newly developed global optimization technique called Differential evolution to optimize the machining parameters of multi-pass turning process. The optimal values of machining parameters such as number of passes, depth of cut in each pass, speed and feed are determined that correspond to the minimum total production cost subject to the technological constraints of allowable speed and feed, surface finish, maximum cutting force and maximum cutting power of the machine tool. An example is taken from the literature to illustrate the proposed procedure.

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A. Gopala Krishna ¹

Affiliations
1 Dept. of Mechanical Engg., J. N. T. University, College of Engg., Kakinada, IN

Abstract

Generation of optimal index positions of cutting tools is an important task to reduce the non-machining time of CNC machines and for achievement of optimal process plans. The optimization model for selecting the optimal sequence forms an NP-hard problem, which is too difficult to solve by the conventional algorithms. The present work proposes the application of a newly developed global search technique, called ants-colony algorithm, for the quick identification of optimal index positions of cutting tools to be used on the tool magazines of CNC machines for executing a fixed set of manufacturing operations. Minimization of total indexing time is taken as the objective function.

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A. Gopala Krishna ¹

Affiliations
1 Dept. of Mechanical Engg., J. N. T. University, College of Engineering, Kakinada-533003, IN

Abstract

Computer aided process planning (CAPP) is an important interface between computer aided design (CAD) and computer aided manufacturing (CAM). CAPP in the past is typically a knowledge-based approach, which is only capable of generating a feasible plan for a given part. The present work involves the application of Differential evolution as a global search technique for a quick identification of optimal or near optimal operation sequences. Minimization of total number of set-up changeovers and tool changeovers is taken as the objective function. Initially, the given part is represented as an assembly of form features, with details of geometric specifications, tolerance and surface finish requirements. To produce each of the form features, the required machining operations are selected. Next, feasibility constraints are considered among various machining operations. The proposed method then finds the optimal sequences within the minimum possible time.

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A. Gopala Krishna ¹

Affiliations
1 Deptt. of Mechanical Engg. J. N. T. University, College of Engineering, Kakinada, IN

Abstract

The allocation of dimensional tolerances directly influences the manufacturing cost and functionality, of a product. The present work reports on a procedure to allocate both design and manufacturing tolerances based on the minimum total manufacturing cost of an assembly The optimization model for tolerance design is a non-linear multivariable problem with multiple constraints. Since such problem may have a noisy surface, there is a need to apply an efficient global optimization technique. In the present work, Scatter search, one of the recently emerged optimization techniques in the area of metaheuristics, is applied successfully to determine the optimal tolerances. An example is taken from the literature to explain the proposed methodology.

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A. Gopala Krishna ¹

Affiliations
1 Department of Mechanical Engineering, J.N.T. University, College of Engineering, Kakinada - 533 003, Andhra Pradesh, IN

Abstract

Drilling accounts for a large proportion of machining operations for many industrial products such as dies and moulds. In this process, when the hole size to be drilled is large, one or more pilot holes have to be drilled before enlarging the hole with a final size drill. The paper presents a procedure to optimize the machining parameters based on a recently developed global optimization technique called scatter search. The total production cost is minimized subjected to the machine tool constraints and technological requirements. Scatter search provides unifying principles for joining solutions based on generalized path constructions in both euctidean and neighborhood spaces and utilizes strategic designs where other approaches like genetic algorithms resort to randomization. In the literature, It is proved that scatter search can produce better results than genetic algorithms. A software program is developed in VC⁺⁺ to get the optimal machining parameters.

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P. Kishore Kumar ¹, N. Vijaya Sai ², A. Gopala Krishna ³, N. G. Renganathan ⁴

Affiliations
1 Dept. of Mech Engineering, Veltech Rangarajan Dr. Sagunthala R&D Institute of Science and Technology, Chennai, Tamilnadu, IN
2 Dept. of Mech Engineering, V R Siddhartha Engineering College, Viayawada, Andhra Pradesh, IN
3 Dept. of Mech Engineering, Jawaharlal Nehru Technological University, Kakinada, Andhra Pradesh, IN
4 Dept. of Chemistry, Veltech Rangarajan Dr. Sagunthala R&D Institute of Science and Technology, Chennai, Tamilnadu, IN

Abstract

Austenitic stainless steels play vital role in high temperature applications. The components used in fission reactors should have better tensile properties at high temperature. To overcome the issues raised by conventional steels, a new group of steels known as oxide dispersion strengthened (ODS) steels are created. Nowadays, two groups of ODS steels such as the ferritic and austenitic ODS steels are being used. The present work mainly focusses on the processing of ODS austenitic steels. The consolidation processes adopted for ODS austenitic steels are discussed in detail. The microstructural features and precipitation of nano-oxides during compaction are also reported. In addition to this, the mechanical properties such as tensile strength and elongation values obtained by various manufacturing processes are also discussed.

Keywords

Oxide Dispersion Strengthened, Austenitic Steel, Consolidation, Nano-Oxides, Tensile Strength and Elongation.

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