Selection of an Optimal Supplier

The paper describes the selection of an optimal supplier from China based on three obtained bids to produce 120,000 forged pieces, which is the primary process for shaft production. The choice was made using the AHP method based on the Expert Choice software program and Multiple-Criteria Decision-Making (MCDM). The key information when choosing the optimal supplier of large number of forgings is to define the objective of the task, decision tree with weighted criteria and sub-criteria, consistency checking and possible reconsideration using brain storming when defining the strength of criteria/sub-criteria. To some extent, this may reduce initial subjectivity in the decision-making process in the Decision Support System

Nonterrestrial utilization of materials: Automated space manufacturing facility

Four areas related to the nonterrestrial use of materials are included: (1) material resources needed for feedstock in an orbital manufacturing facility, (2) required initial components of a nonterrestrial manufacturing facility, (3) growth and productive capability of such a facility, and (4) automation and robotics requirements of the facility

Development of an Intelligent Knowledge Based System (IKBS) for forging die design

The work in this thesis is concerned with further development of an Intelligent Knowledge-Based System (IKBS) for forging die design. It follows on from initial work carried out at the School of Manufacturing and Mechanical Engineering. The main parts of the original design for the system are a sequence design program (SDP) for two and three dimensional parts, an interface program which can be connected to a finite-element program for metal forming simulation and a Control Module which supervises these two parts and co-ordinates their activities. Of these three modules, only the SDP and the Control Module existed when the current work was started. The purpose of the work reported here is to develop, improve and validate the original system. Among the five different families of components within the original IKBS, Stub Axles have been selected for the current research work. An interface program has been written which can generate a datafile for the available finite-element program (EPFEP3). This interface program inputs one preform stage as the geometry for mesh generation and the corresponding product stage in order to determine the boundary conditions. It also inputs the data within the SDP database for completing the other parts of the datafile. This program is efficient, rapid and user friendly and can easily be extended for the other families of components in the SDP. In the IKBS, when a new component is input to the system, each forming stage of the component should be compared with the same stage of the same family of all the components stored in the database. To do so, the significant processing and geometrical parameters and also their weighting effects should be input to the system. A new experimentally-based approach has been developed to obtain the weighting effects of the significant parameters. The weighting factors obtained are saved in the knowledge-base and have been shown to lead to the correct predictions when data for real forgings was used. The method for obtaining the weighting effects of the significant parameters can be extended to the other families of components within the IKBS. Programs have been written to perform computer-aided reasoning in the IKBS. In particular, recognising and extracting the values of the significant parameters of the operational sequence of a component, creating the IKBS database based on real data and performing the comparison procedure for a new component stage with those stored in the IKBS database

Annual Report 1982-1983

It contains the statement of R&D works undertaken, achivement made and the expenditure by the laboratory during the financial year 1982-1983

Optimization of industrial processes for forging of carbon and stainless steels

The possibility to produce stainless steel components at limited cost and characterized by elevated mechanical properties, has gained more importance in the last years. Nowadays, the cold and warm forging processes of carbon steels are widely used to form industrial parts due to their economic advantages, but there is still lack of extensive research on industrial process design and evaluation of the microstructural properties of cold-warm forged stainless steel parts. In the last few decades, the environment concerning the recent forging industry has been rapidly changed. Now, near-net-shape or net-shape manufacturing processes are becoming a useful practice in metal forming, resulting in saving material and energy. Many parts produced with machining can be manufactured at lower cost by cold and warm forging. Traditionally, forging design is carried out using mainly empirical guidelines, experience, and trial-and-error, which results in a long process development time and high production costs. In order to avoid this, in recent years, computer-aided simulation approaches have proved to be powerful tools to predict and analyze material deformation during a metal forming operation. There are now many commercial finite-element (FE) packages to simulate forging and bulk metalworking processes. To date, most have focussed on predicting the shape of the final product after simple or complex single- or multi-stage forming operations. On the other hand, other aspects are being included in these numerical models, such as an improved understanding of the constitutive material behaviour, friction and lubrication conditions, and the properties of the final product, in order to predict more complicated phenomena such as tool life prediction, ductile fracture and microstructure evaluation. The focus of this PhD thesis is the development of an innovative approach based on the design of integrated experimental procedures and modelling tools, in order to accurately re-design a range of industrial single-stage cold-warm forming processes to form stainless steel components and investigate the microstructural evolution of forged parts obtained at different forging temperatures. In addition, the design of a multi-stage cold forging process of a low-carbon steel and the prediction of surface defects that occur in each stage of the forming-sequence have been carried out. To this aim, a series of tensile tests were conducted to evaluate the influence of temperature and strain rate on the materials elasto-plastic properties. Futhermore, an innovative experimental setup was used to reproduce the realistic friction conditions at the tool-workpiece interface, in order to accurately predict metal flow during forging cycles. Experimental data were subsequently validated and implemented in a commercial 3D-FE software and accurately calibrated to perform fully coupled numerical simulations for the reference processes. Finally, the forged parts obtained were characterized by macro- and microstructural inspections in order to evaluate the presence of underfilling problems and surface defects, which were consistent with the numerical FE results coming from both simulated processes (i.e. single- and multi-stage forging), and to analyze the microstructural evolution of α- and γ-phase during single-stage tests both at room temperature and from 400 to 700 °C. The materials investigated in this work are low-carbon AISI 1005 ferritic-pearlitic steel (Wr. N. 1.0303), AISI 304L austenitic (Wr. N. 1.4307) and commercially named Duplex 2205 ferritic-austenitic stainless steel (Wr. N. 1.4462). The developed experimental tests are suitable to proper evaluation of steels behaviour in terms of mechanical properties, and to precisely calibrate coupled numerical models when they are applied to conventional and re-design forging processes. The techniques used in this work include: tensile tests, T-shape compression tests, visual inspections (i.e. supported by vernier calliper and micrometer measurements), hardness and micro-hardness tests, LOM (Light Optical Microscopy), FEG-ESEM (Field-Emission Gun Environmental Scanning Electron Microscope), EDS (Energy Dispersive X-ray Spectroscopy), EBSD (Electron Back Scattering Diffraction) and numerical models carried out with FORGE2011®-3D

Development of a manufacturing feature-based design system

Traditional CAD systems are based on the serial approach of the product development cycle: the design process is not integrated with other activities and thus it can not provide information for subsequent phases of product development. In order to eliminate this problem, many modern CAD systems allow the composition of designs from building blocks of higher level of abstraction called features. Although features used in current systems tend to be named after manufacturing processes, they do not, in reality, provide valuable manufacturing data. Apart from the obvious disadvantage that process engineers need to re-evaluate the design and capture the intent of the designer, this approach also prohibits early detection of possible manufacturing problems. This research attempts to bring the design and manufacturing phases together by implementing manufacturing features. A design is composed entirely in a bottom-up manner using manufacturable entities in the same way as they would be produced during the manufacturing phase. Each feature consists of parameterised geometry, manufacturing information (including machine tool, cutting tools, cutting conditions, fixtures, and relative cost information), design limitations, functionality rules, and design-for-manufacture rules. The designer selects features from a hierarchical feature library. Upon insertion of a feature, the system ensures that no functionality or manufacturing rules are violated. If a feature is modified, the system validates the feature by making sure that it remains consistent with its original functionality and design-for-manufacture rules are re-applied. The system also allows analysis of designs, from a manufacturing point of view, that were not composed using features. In order to reduce the complexity of the system, design functionality and design-for manufacture rules are organised into a hierarchical system and are pointed to the appropriate entries of the feature hierarchy. The system makes it possible to avoid costly designs by eliminating possible manufacturing problems early in the product development cycle. It also makes computer-aided process planning feasible. The system is developed as an extension of a commercially available CAD/CAM system (Pro/Engineer), and at its current stage only deals with machining features. However, using the same principles, it can be expanded to cover other kinds of manufacturing processes

The development of a metallurgical CAPP system for large steel forgings.

The development of CAPP (Computer Aided Process Planning) systems promises improvement to the design efficiency and quality of process plans, whilst maintaining knowledge for future developments. Although considerable progress has been made in Computer Aided Process Planning, most of the systems developed or under development so far are limited to one manufacturing operation and to planning for an individual part design. The systems lack an overall structure for real manufacturing practice. This thesis examines the problems involved in the planning of an extensive manufacturing task involving many different processes including chemical and thermal treatments. On the basis of the evaluation of the manufacturing system in the collaborating company, an intelligent database system has been designed to solve metallurgical process planning problems involved in the manufacture of large steel forgings. In this CAPP database system, two hierarchy control levels involving a number of local planning areas have been adopted to allow the development of process sub-plans as well as supporting engineering data. All the process sub-plans have been integrated into a single system rather than isolated as separate entities within the overall metallurgical process planning system together with quality assurance control and other functions. These sub-plans, however, are planned and modified in the separate planning areas, the development being conducted on facsimile data records. Only when each sub-plan has reached a satisfactory state of development is it issued - made available to the overall system - by transferring the facsimile records into the system data files, the facsimile records then being discarded.Metallurgical process knowledge and rules have been incorporated into the database. These allow the system to assist users to make decisions and achieve final desired process plans. A versional approach has been developed to organise and control the stage by stage evolution of issued process plans within this complex steel forging environment. The use of separate planning areas and local facsimile records allows the modification of sub-plans already issued to be undertaken on a step by step but secure basis. A fully operating authorisation system controlling access to the data and the deletion or modification of records has been achieved. This is essential in a CAPP system of this type in which historical decisions, or approved rules based on historical experience, are presented to the users as the basis to make new decisions.The work has been extended to explore external enhancement of the central database system with an expert system and with specially written C ++ programmes. The system architecture needed to support this link is described, and issues raised by the enhancement that relate to the overall control are then addressed. The final part of the thesis examines the limitations of the method that has been developed and discusses difficulties involved in implementing a CAPP system in a large concern involved in the 'bespoke' manufacture of complex engineering artifacts on a one-off design basis

Hybrid Bulk Metal Components

In recent years, the requirements for technical components have steadily been increasing. This development is intensified by the desire for products with a lower weight, smaller size, and extended functionality, but also with a higher resistance against specific stresses. Mono-material components, which are produced by established processes, feature limited properties according to their respective material characteristics. Thus, a significant increase in production quality and efficiency can only be reached by combining different materials in a hybrid metal component. In this way, components with tailored properties can be manufactured that meet the locally varying requirements. Through the local use of different materials within a component, for example, the weight or the use of expensive alloying elements can be reduced. The aim of this Special Issue is to cover the recent progress and new developments regarding all aspects of hybrid bulk metal components. This includes fundamental questions regarding the joining, forming, finishing, simulation, and testing of hybrid metal parts