Showing papers on "Material flow published in 2009"

Strategic Information Management Under Leakage in a Supply Chain

Abstract: The importance of material flow management for a profit-maximizing firm has been well articulated in the supply chain literature. We demonstrate in our analytical model that a firm must also actively manage information flows within the supply chain, which translates to controlling what it knows, as well as what its competitors and suppliers know. In our model of horizontal competition between an informed and an uninformed firm with a common upstream supplier, material and information flows intersect through leakage of demand (order) information to unintended recipients. As a result, the informed firm's drive to control information flows within the supply chain can trigger operational losses through material flow distortion. These losses can be so severe that the firm may prefer not to acquire information even when it is costless to do so. Our results underscore the importance of strategic information management---actively managing the supply chain's information flows, and making trade-offs with material flows where appropriate, to maximize profits.

A 3D numerical simulation of different phases of friction stir welding

Abstract: An adaptive arbitrary Lagrangian–Eulerian formulation is developed to compute the material flow and the temperature evolution during the three phases of the friction stir welding (FSW) process. It follows a splitting approach: after the calculations of the velocity/pressure and temperature fields, the mesh velocity is derived from the domain boundary evolution and from an adaptive refinement criterion provided by error estimation, and finally state variables are remapped. In this way, the unilateral contact conditions between the plate and the tool are accurately taken into account, so allowing one to model various instabilities that may occur during the process, such as the role played by the plunge depth of the tool on the formations of flashes, the possible appearance of non-steady voids or tunnel holes and the influence of the threads on the material flow, the temperature field and the welding efforts. This formulation is implemented in the 3D Forge3 FE software with automatic remeshing. The non-steady phases of FSW can so be simulated, as well as the steady welding phase. The study of different process conditions shows that the main phenomena taking place during FSW can be simulated with the right sensitivities.

Material flow stress and failure in multiscale machining titanium alloy Ti-6Al-4V

Abstract: Titanium Ti-6Al-4V alloy is a typical difficult-to-machine material due to its unique physical and mechanical properties. The material properties of Ti-6Al-4V play an important role in process design and optimization. However, the dynamic mechanical behavior is poorly understood and accurate predictive models have yet to be developed. This work focuses on the dynamic mechanical behavior of machining Ti-6Al-4V beyond the range of strains, strain rates, and temperatures in conventional materials testing. The flow stress characteristics of strain hardening and thermal softening can be predicted by the Johnson–Cook model coupled with the adiabatic condition. The predicted flow stresses at small strains agree very well with those from the split Hopkinson pressure bar (SHPB) tests, while the predicted flow stresses at large strains also agree with the calculated flow stresses based on the cutting tests with a suitable depth of cut. Heat fraction and temperature parameter control the range of thermal softening and the decrease rate of flow stress. The material may exhibit super plasticity at a small depth of cut with a large radius of the cutting edge in micromachining. Strain rate is one important factor for material fracture close to the cutting edge. The failure strain increases linearly with the increase of homologous temperature, while it only increases slightly with the strain rate.

Zero carbon manufacturing facility — towards integrating material, energy, and waste process flows

Abstract: The increasing pressure on material availability, energy prices as well as emerging environmental legislation is leading manufacturers to adopt solutions to reduce their material and energy consumption as well as their carbon footprint, thereby becoming more sustainable. Ultimately manufacturers could potentially become zero carbon by having zero net energy demand and zero waste across the supply chain. Literature on zero carbon manufacturing, and the technologies that underpin it, is growing but there is little available on how a manufacturer undertakes the transition. Additionally, the work in this area is fragmented and clustered around technologies rather than around processes that link the technologies together. There is a need to better understand material, energy and waste process flows in a manufacturing facility from a holistic viewpoint. With knowledge of the potential flows, design methodologies can be developed to enable zero carbon manufacturing facility creation. This paper explores the challenges faced when attempting to design a zero carbon manufacturing facility. A broad scope is adopted from legislation to technology and from low waste to consuming waste. A generic material, energy and waste flow model is developed and presented to show the material, energy and waste inputs and outputs for the manufacturing system and the supporting facility and, importantly, how they can potentially interact. Finally the application of the flow model in industrial applications is demonstrated to select appropriate technologies and configure them in an integrated way.

Quantifying supply chain disruption risk using Monte Carlo and discrete-event simulation

Abstract: We present a model constructed for a large consumer products company to assess their vulnerability to disruption risk and quantify its impact on customer service. Risk profiles for the locations and connections in the supply chain are developed using Monte Carlo simulation, and the flow of material and network interactions are modeled using discrete-event simulation. Capturing both the risk profiles and material flow with simulation allows for a clear view of the impact of disruptions on the system. We also model various strategies for coping with the risk in the system in order to maintain product availability to the customer. We discuss the dynamic nature of risk in the network and the importance of proactive planning to mitigate and recover from disruptions.

A First-Order Hybrid Petri Net Model for Supply Chain Management

Abstract: A supply chain (SC) is a network of independent manufacturing and logistics companies that perform the critical functions in the order fulfillment process. This paper proposes an effective and modular model to describe material, financial and information flow of SCs at the operational level based on first-order hybrid Petri nets (PNs), i.e., PNs that make use of first-order fluid approximation. The proposed formalism enables the SC designer to choose suitable production rates of facilities in order to optimize the chosen objective function. The optimal mode of operation is performed based on the state knowledge of the obtained linear discrete-time, time-varying state variable model in order to react to unpredictable events such as the blocking of a supply or an accident in a transportation facility. A case study is modeled in the proposed framework and is simulated under three different closed-loop control strategies.

A Material History of Australia: Evolution of Material Intensity and Drivers of Change

Abstract: Summary This article presents an analysis of the material history of Australia in the period 1975–2005 The values of economy-wide indicators of material flow roughly trebled since 1975, and we identify the drivers of this change through structural decomposition analysis The purpose of this work is to delve beneath the top-level trends in material flow growth to investigate the structural changes in the economy that have been driving this growth The major positive drivers of this change were the level of exports, export mix, industrial structure, affluence, and population Only improvements in material intensity offered retardation of growth in material flow Other structural components had only small effects at the aggregate level At a more detailed level, however, the importance of the mineral sectors became apparent Improvements in mining techniques have reduced material requirements, but increased consumption within the economy and increased exports have offset these reductions The full roll out of material flow accounting through Australian society and business and a systematic response to its implications will require change in the national growth focus of the last two generations, with serious consideration needed to reverse the current volume-focused growth of the economy and also to recast neoliberal and globalized trade policies that have dominated the globe for the past decades

Coordinating material and information flows with supply chain planning

Abstract: Purpose – The purpose of this paper is to study how companies can select a supply chain planning (SCP) mechanism to improve the balance between material flow and information flow.Design/methodology/approach – The methodology of the paper is an inductive case study approach. Coordination theory is used as a background for the paper. Based on a literature survey, determinants of the selection of a SCP approach are defined. Cases of SCP are used to validate the framework presented.Findings – The paper suggests that specific supply chain characteristics need to be balanced by selecting a coordination mechanism that uses information optimally to support the material flow. Flexible material flow needs frequent updates of the plan based on accurate information. If frequent information sharing and planning practices are used to support inflexible material flow, the result may be volatility in plans, and planning resources are wasted. If a flexible material flow is supported by inadequate information, waste may be...

On the material flow in FSW of T-joints: Influence of geometrical and tecnological parameters

Abstract: Friction stir welding (FSW) now definitively reached a large interest in the scientific community and what is more in the industrial environment, due to the advantages of such solid state welding process with respect to the classic ones. The latter aspects are relevant also with reference to joints characterized by a complex geometry. What is more, advanced FEM tools permit to develop effective engineering of the processes; quantitative results can be acquired from numerical simulations once basic information, as the process mechanics and the material flow, are certain. Material flow plays a fundamental role in FSW since it determines the effectiveness of the joints or, in turn, the insurgence of defects. In the paper, the material flow in the FSW of aluminum alloys T-joints is investigated at the varying of the most relevant technological and geometrical parameters with numerical simulations and experiments. In particular, to investigate the metal flow, a wide campaign of experimental tests and observations was developed utilizing a thin foil of brass as marker, placed at the interface of the two blanks to be welded. Some relevant conclusions on the process mechanics and on the actual material flow determining the material bonding are outlined, permitting an insight of the FSW of T-joints.

An new approach for the automatic analysis and control of material handling systems: integrated layout flow analysis (ILFA)

Abstract: In the majority of small and medium sized enterprises (SEMs), the direct costs of material handling cannot be clearly measured. There are several reasons for this, including the large number of product types, complexity of their production cycle, and continuous change in markets. Therefore, production managers require flexible tools to create a suitable material handling system model which explicitly and rapidly calculates the indices required as these are traditionally neglected or laboriously approximated, (i.e., time and cost in material flow inside the factory, storage area requirements, and MH utilization percentage). This paper proposes an integrated approach to analyzing and controlling material handling operations in an industrial manufacturing plant from a “full quantitative” point of view. The model presented unites quite different fields of research into a unique methodology. This material handling model rapidly and automatically provides production managers with extensive and significant information. As a result, integrated layout flow analysis interrelates systematic layout planning with operational research algorithms and visual interactive simulation, using a complete software platform to implement them. This integrated layout flow analysis approach focuses on determining the space requirement for manufacturing department buffers, the transportation system requirements, the performance indices, and the time and cost of material flows spent in the layout and in MH traffic jams.

An integrated approach to determine the block layout, AGV flow path and the location of pick-up/delivery points in single-loop systems

Abstract: Layout design and material handling system design are two of the major aspects of facility planning. Although both aspects directly influence each other, the classical approach to the layout design is carried out in two separate steps: in the first step the block layout, i.e. the location of the departments in the workshop, is constructed, and in the second step, the material handling system is designed. The separate optimisation of these two aspects of the problem leads to solutions that can be far from the global optimum. In this paper, we develop an integrated algorithm to design the facilities and material handling systems. We focus on single-loop AGV systems. The proposed algorithm determines the block layout, AGV single-loop flow path and pick-up delivery stations, simultaneously. The associated from–to chart and the area of departments are the principal inputs of the algorithm. The objective is minimising total material flow distance among all departments. The results of our computational experimen...

Thermomechanical Modelling of Friction Stir Welding

Abstract: Friction Stir Welding (FSW) is a fully coupled thermomechanical process and should in general be modelled as such. Basically, there are two major application areas of thermomechanical models in the investigation of the FSW process: i) Analysis of the thermomechanical conditions such as e.g. heat generation and local material deformation (often referred to as flow) during the welding process itself. ii) Prediction of the residual stresses that will be present in the joint structure post to welding. While the former in general will call for a fully-coupled thermomechanical procedure, however, typically on a local scale, the latter will very often be based on a semi-coupled, global procedure where the transient temperatures drive the stresses but not vice-versa. However, in the latter, prior knowledge about the heat generation must be obtained somehow, and if experimental data are not available for the FSW process at hand, the heat generation must either be prescribed analytically or based on a fully coupled analysis of the welding process itself. Along this line, a recently proposed thermal-pseudo-mechanical model is presented in which the temperature dependent yield stress of the weld material controls the heat generation. Thereby the heat generation is still numerically predicted but the cumbersome fully coupled analysis avoided. In the present work the formulation of all three mentioned modelling approaches as well as the very fundamental pure thermal models are briefly presented and discussed together with selected modelling results including prediction of material flow during welding, prediction of heat generation with the thermal-pseudo mechanical model as well as residual stress and deformation analysis combined with in-service loads.

Combination of job oriented simulation with ecological material flow analysis as integrated analysis tool for business production processes

Abstract: This paper outlines the application of a special Environmental Management Information System (EMIS) as combination of discrete event simulation with ecological material flow analysis for a selected production process. The software tool serves as decision aid for economic as well as ecological business problems. A combined view of the material flow as well as job-oriented view on an enterprise allows for a unified and efficient model building process. This contribution summarizes the underlying concepts and the experiences with the development and utilization of a suitable software tool following this integrated view and describes the concrete problems and solutions at the example of modeling a complex semiconductor fabrication.

Bulk material transport system

Abstract: In a material handling system having a material feeder, a material container may be configured to discharge material to the material feeder and a process aid may be engaged with the material container, a method including determining a process indicator associated with a material flow characteristic of the feeder during operation of the feeder, determining a difference between the process indicator and an indicator threshold value, adjusting the operation of the process aid based on the value of the difference determined above between the process indicator and the indicator threshold value.

3D modeling of material flow and temperature in Friction Stir Welding

Abstract: The process of Friction Stir Welding (FSW) is a welding method developed by the "The Welding Institute" (TWI) of England in 1991. The welding equipment consists of a tool that rotates and progresses along the joint of two restrained sheets. The joint is produced by frictional heating which causes the softening of both components into a viscous-plastic condition and also by the resultant flow between the sheets to be joined. Numerical Modeling of the process can provide realistic prediction of the main variables of the process, reducing the number of experimental tests, thus accelerating the design processes while reducing costs and optimizing the involved technological variables. In this study the friction stir welding process is modeled using a general purpose finite element based program, reproducing the material thermal map and the corresponding mass flow. Numerical thermal results are compared against experimental thermographic maps and numerical material flow results are compared with material flow visualization techniques, with acceptable concordance.

Analysis of the Hydraulic Bulge Test with FEA Concerning the Accuracy of the Determined Flow Curves

Abstract: This work covers the finite element analysis of geometric and process parameters in hydraulic bulge tests in terms of the accuracy of the evaluated flow curve. The important parameters are identified and varied to cover the whole range of possible uses. The effects of these parameters are analyzed for three representative materials: aluminium, mid-strength steel, and high-strength steel. The flow curves of the materials for each set of parameters are calculated by using the results of the simulations and the membrane theory. It is seen that even with simulation results, it is not always possible to obtain the input flow curve, especially towards the end of the test. The dimensions of the sheet and the tooling affect the plastic strain development and geometry of the bulge, leading to errors in computed flow curves. In order to observe the effect of the material flow from the flange on the determined yield stresses, the function and position of the drawbeads are also examined. These parameters, together with the method used to calculate the radius of the bulge, determine the accuracy of the calculated flow curve. Guidelines for an accurate flow curve determination regarding the test set-up and calculation methods are given.

The Impact of Blasting on Sublevel Caving Material Flow Behaviour and Recovery

Abstract: nSublevel caving (SLC) is a mass mining method based upon the utilisation of gravity flow of blasted ore and caved waste rock. The method functions on the principle that ore is fragmented by blasting, while the overlying host rock fractures and caves under the action of mine induced stresses and gravity. The caved waste from the overlying rock mass fills the void created by ore extraction. A major disadvantage of the SLC mining method is the relatively high dilution of the ore by caved waste. A major factor influencing this dilution is the flow behaviour of the ore and waste material. For this reason, flow behaviour has been studied and quantified through theoretical, small and full scale experimental programs for almost 50 years. These programs have attempted to identify parameters which have a significant influence on flow behaviour, and therefore ore recovery and dilution results. Parameters directly influencing flow performance have been found to include the geometry of the extraction layout and drives, sublevel height, blast ring design, material characteristics of the blasted and waste material, and draw control methodology. Due to the complex interaction of these parameters with one another, a total understanding of the impact of SLC mining on flow behaviour is not fully understood. Drill and blast issues have been identified in the literature to have a substantial impact upon SLC material flow. These issues relate to both drill and blast design parameters and design implementation. Increases in SLC geometry size have meant the development of longer and larger diameter blast holes, and improvements in explosive and blasting methods. This has in turn lead to large mine cost savings due to decreased development costs. Such significant changes in the drill and blast design would be expected to have an impact on blasted and caved material properties, and therefore material flow behaviour. Dominantly, the literature has made general conclusions concerning the interaction of drill and blast parameters and flow behaviour, with respect to the knowledge that blasting has a direct impact on ore and caved flow material properties. A limited number of studies have related drill and blast parameters to indirect measures of material flow behaviour, in particular ore recovery and dilution. To date, no detailed analysis of the impact of drill and blast parameters on material flow behaviour in full scale SLC operations has been documented in the literature. The implementation of full scale SLC marker trials has been noted in the literature to be crucial for the ongoing success of the mining method. Such trials provide detailed information concerning the development and shape of the extraction zone, identify possible sources of waste ingress into the ring, and ascertain the degree of flow behaviour variability. The marker trials undertaken at the Ridgeway SLC gold mine provide a unique opportunity to assess these factors. These trials are considered to be the most comprehensive to date, with 69 individual ring trials completed from July 2002 to April 2005. The Ridgeway marker dataset was used in this thesis to assess and quantify factors influencing material flow behaviour and extraction zone recovery. It can generally be concluded from the Ridgeway marker trials that the shape of the extraction zones were irregular in nature (not described by an ellipsoid shape), with primary recovery consisting of an area of lcontinuous flowr near the blast ring plane and lfingersr of recovery further from the blast ring plane. The backbreak extraction zone is relatively common, with highest recoveries occurring in close to the previously fired blast burden. Secondary, tertiary, and quaternary recoveries occur as relatively small discrete zones within the blasted material. An analysis was undertaken to identify factors that influence extraction zone recovery for the Ridgeway marker trial dataset. Factors analysed included parameters related to drawpoint location, drill and blast design, geology, drawpoint geometry, and draw control. To identify factors influencing extraction zone recovery, a neural network technique was adopted. The analysis indicated that a number of blasting parameters are directly or inversely correlated to extraction zone recovery for the marker trials. Blasting parameters appear to dominate correlations with recovery when compared to geological and drawpoint related parameters. Although the neural network methodology provides a rigorous means to identify possible correlations between parameters, further data analysis was required to understand the nature and characteristics of these relationships. Correlations identified by the neural network analysis were analysed in two dimensions, and did not consider multivariable relationships. Traditional statistical methods were employed to investigate and characterise these correlations. For categorical blasting parameters, non-parametric tests were used to determine if significant statistical differences existed between categorical groups. For continuous blasting parameters, the assumption of a linear correlation was made to quantify the strength and significance of such a relationship existing. Based upon the statistical analysis a number of possible theories were proposed with regard to the impact of blast parameters on extraction zone recovery. Although the correlations analysed do not necessarily prove causality, the correlations can be linterpretedr in causal terms to propose a number of blast related theories with respect to recovery. To develop these theories, both correlations between blasting parameters and extraction zone recovery as well as blast related inter-parameter correlations were considered. The most likely theory based upon this analysis is that a fundamental change in drill and blast design at Ridgeway with the removal of blast holes resulted in lower extraction zone recoveries (in particular primary recovery close to the blast ring plane). The reduction in the number of blast holes in turn impacted on total secondary to quaternary extraction zone recovery either directly (due to factors such as poor fragmentation and limited swell) or indirectly through reduced primary recovery (leading to subsequent lower total secondary to quaternary recoveries). Recovery in the marker ring planes is directly related to proximity of the blast ring plane. The results and conclusions presented in this thesis provide an improved understanding of full scale SLC flow behaviour and recovery. In particular, parameters significantly influencing extraction zone recovery were identified. The analysis highlights and quantifies the importance of drill and blast design and implementation on improved extraction zone recovery.

Modeling of friction stir processing using 3D CFD analysis

Abstract: Friction Stir Processing (FSP) has emerged as an effective tool for enhancing sheet metal properties through microstructural modification of processed materials. Despite the large number of studies, most of the work that has been done in the FSP field focuses primarily on experimental work. Only limited modeling attempts on temperature distribution and strain rate analysis have been conducted. In this work, a three dimensional Computational Fluid Dynamics (CFD) model was developed to simulate FSP using the STAR CCM+ CFD commercial software. User-defined subroutines were developed and implemented to investigate the effects of process parameters on temperature, strain rate, flow stress and material velocity fields in, and around, the processed nugget. In addition, a correlation between process parameters and the Zener-Holloman parameter was developed to predict the grain size distribution in the processed zone. Different stirring conditions were incorporated in this study to investigate their effects on material flow and microstructural modification. The modeling results were compared with the available experimental data and showed good agreement.

Discrete time analysis of batch processes in material flow systems

Abstract: Scope of this work is the development of appropriate models for the evaluation of batch processes in material flow systems. The presented analytical methods support the long range planning in an early planning stage, in which capacities are determined to minimize the facility costs under the condition of cycle time targets. Umfang: XIV, 137 S. Preis: €31.50 | £29.00 | $56.00

Multiagent Approach for Supply Chain Integration by Distributed Production Planning, Scheduling and Control System

Abstract: The changing business environment in which manufacturers are acting creates the need for more effective production processes planning, scheduling and control methods that are able to deal with uncertainties inherent in internal processes and external deliveries. The aim of the paper is to introduce the multiagent approach method for production planning, scheduling and control applicable in conditions of supply chain (SC) able to overcome the limitation of standard MRP/ERP systems in changing environment. Traditional approaches very often do not consider the influence of uncertainty inherent in production processes and supplies. Therefore, there is a need for the integration of manufacturing process planning, scheduling and control systems for generating more realistic and effective plans. Conceptual framework for the multiagent approach method involves the hybrid solutions combining the advantages of MRP simple logic and theory of constrains (TOC) ability to synchronize all production and material flow in supply chain. Authors discuss how application of TOC buffers monitoring procedures can help to improve the control of synchronized production and material flow in supply chain.

Material flow analysis for hot-forming of 20MnCr5 gear wheel blanks

Abstract: During the manufacture of disk-like gearwheel blanks made of 20MnCr6 (SAE 5120) a characteristic distortion behavior was observed which has been related to the forging process. The steel showed a typical banded structure and a distribution of chemical elements (segregations) perpendicular to rolling direction. When analyzing the micrographs of the forged gearwheel blanks, a significant variation in the material flow was found. In order to clarify the cause of the observed material flow variations and to determine its impact on the distortion potential of the disks, a twofold approach has been applied: a) to determine and to describe the material flow characteristics on basis of micrographs of forged disks and b) to carry out FE-analyses on the theoretical material flow and its parameters. In this contribution results of the material flow analysis are presented and compared with FE-analyses of the forming process.

Material flow control apparatus and method for sintered batching ore storage bin

Abstract: The invention specifically discloses a material flow control device applied to a sintering proportioning ore bunker. The device is connected with a blanking device group and comprises an actual flow acquisition unit, a set flow acquisition unit and a blocking material judgment unit, wherein, the actual flow acquisition unit is connected with a weighing device of the blanking device group to acquire the actual value of blanking flow of the blanking device in real time; the set flow acquisition unit is connected with an electric motor to acquire the set value of blanking flow of the blanking device in real time; the blocking material judgment unit is used for outputting a blocking material warning signal when the ratio of the actual value to the set value of the blanking flow of the blanking device is less than the preset percentage. The invention also discloses a material flow control method applied to the sintering proportioning ore bunker. With the device and method of the invention adopted, the material flow state inside the ore bunker can be detected in real time and the sintering production can run smoothly.

Multi-chamber vibrating valve for cementitious material

Abstract: A nozzle for extruding cementitious material may include an outlet sized and configured to extrude the cementitious material, a material flow pathway configured to channel the cementitious material to the outlet, and a vibration-actuated valve interposed in the material flow pathway. The valve may include a plurality of spaced-apart plates configured to form a plurality of flow channels, and a vibration-generating device coupled to the plates and configured to controllable cause the plates to controllably vibrate. The vibration-actuated valve may be configured such that the cementitious material must flow through the channels formed by the plates in order to reach the outlet, The spacing between the plates and the surface of the plates may be in amounts which collectively cause the flow of the cementitious material though the plurality of flow channels to be blocked when the vibration-generating device is not vibrating, and the cementitious material to flow through the plurality of flow channels simultaneously when the vibration-generating device is vibrating.

Analysis of the dynamics between supply chain flexibility and key management ratios

Abstract: Managing flexibility in supply chains involves a variety of actions, at various stages of designing, using and improving the supply chain system. This problem has very close association with various financial factors in business and therefore with the Key Management Ratios (KMRs) which are of considerable interest to corporate managers. The language of money binds various segments of any supply chain, in which the operational managers are busy dealing with information flow and material flow, to facilitate the desired cash flow to happen. Business management ratios are considered as the guiding stars for corporate managers as they are believed to capture the real status of the business, under different scenarios. However, as far as the Supply Chain Flexibility (SCF) is concerned, these two issues are not discussed jointly. There are many types of supply chain flexibilities and various KMRs. It is perhaps difficult to establish generalised relationships between these two sets of entities. A study was carried out to assess the influence that may be exerted by various types of SCF on the elements of KMRs and eventually, the KMRs themselves, the findings of which are reported in this paper.