Material Flow Control Research Articles

An investigation into the preforming of tubes

A major disadvantage of traditional cold forging is represented by the inability to forge slender geometries such as tubes, because these tend to collapse under axial forces. Recent research has revealed that, for the forming of hollow flanged components from tubes, a controlled material flow can be achieved by injection forging. However if the height of the flange is high compared to the wall thickness of the tube, instability problems arise causing the tube to buckle. According to previous work by the authors this may be prevented by increasing the wall thickness of the tube locally through the preforming of a simple inner flange on the tube. These preliminary investigations have been restricted to a reduced number of component geometries in terms of the major process parameters; being the inner- to outer-tube diameter proportion and the flange-towall-thickness ratio. In continuation of this work the present paper focuses on a systematic mapping of the optimal preform design in order to allow an establishment of actual preform design rules for the injection forging of tubular components for a whole range of parameter combinations. The analysis builds on a comprehensive finite element analysis in conjunction with experimental tests in aluminium performed for strategically important parameter combinations in order to support the theoretically established formability limit diagrams.

Control of material flow in a combined backward can - forward rod extrusion

The paper deals with an analysis of an extrusion process with a divided material flow. As we are forced to seek for optimal technological solutions with short testing times and low risks and costs, a reliable process evaluation is of the greatest importance. The paper discusses the influences of tool geometry, friction and lubrication as well as workpiece properties on balanced material flow in a combined extrusion process. The FEM analysis applying the DEFORM code has been used in order to predict the process parameters and to estimate its stability. The subsequent experimental verification has resulted in a conclusion that modern computer aided tools, tuned by proper experimental sets, can be used for fast and reliable cold metal forging process planning.

5388535 Waste material flow control features in a material processing apparatus: Eshleman Roger Waynesboro, PA, 17268, United States

5388535 Waste material flow control features in a material processing apparatus: Eshleman Roger Waynesboro, PA, 17268, United States

Literature review of material flow control mechanisms

Abstract We review mechanisms which control the flow or material into and within a manufacturing line. These material flow control (MFC) mechanisms address the problem of when to release material into a manufacturing line and when workcentres should be authorized to produce. The MFC mechanisms reviewed include: Kanban, CONWIP, workload regulating, starvation avoidance, BORA, maximum load limit, MRP, the base stock system, workload control, and production authorization cards.

Modelling of part shape and deformation evolution in the conventional forming of large sheet-metal components

This paper deals with algorithms implemented in production software used for the modelling of conventional three-piece die sheet-forming processes. The topics considered are the CAD interface, the initial evaluation of forming severity based on an “ideal deformation” algorithm, the development of addendum surfaces, the application of finite-element algorithms for the calculation of the binder wrap surface and the blank shape, the interactive control of material flow during die design, and die try-out simulation.

Using production and transfer batches in flowshops under MRP control

Abstract This study investigates the impact of using material flow control and order release throttling mechanisms on shop floor effectiveness in MRP based order release environments. The research methodology involves simulation experiments conducted using a flow shop model of a manufacturing and assembly setting. Specifically addressed issue is the decoupling of shop floor control decisions from MRP release schedules. This decoupling effect is implemented through the use of smaller production batch sizes, staggering the release of the production quantities to initial work stations, and using transfer batches. In a 14 parts/9 processes simulation environment, the effects of shop floor control decisions are evaluated based on average hours of work in process inventory and average number of tardy units for the simulated planning horizon. Experimental results suggest that increasing material flow frequency through smaller process and transfer batch sizes have significant consequences on inventory and service levels. By separating work in process inventories into two components, it is shown that reducing batch sizes may not affect inventory levels of asynchronized assembly units (i.e. component delay). The results also indicate the presence of a possible threshold effect for throttling and staggering work order releases where service levels are compromised and marginal gain on inventory reduction diminishes.

Network Scheduling Development in an MRP II Environment

Large manufacturing industries have been able to successfully reduce cost and cycle time through the use of Manufacturing Resource Planning (MRP II) systems and principles to control material flow and the production process. Ship construction cannot be neatly classified as a manufacturing process. The complex relationships involved with the installation and activation of ship's systems more closely resembles a construction operation. Work of this type has traditionally been controlled through an activity based network scheduling system. However, MRP II principles offer numerous benefits for the shipbuilding industry. This paper discusses an approach to planning, scheduling, and management of ship construction which takes advantage of benefits from both approaches. By using both network scheduling and MRP II in an integrated scheduling system, a shipyard will be better able to plan and execute the ship construction process.

Simulation models for the management of materials flow in manufacturing systems: a case study

The aim of this paper is to discuss the potential for simulation models to become part of decision support tools for manufacturing decision makers, rather than just a tool for simulation experts. Simulation also has a part to play in data– and knowledge–based manufacturing control systems. To demonstrate how such a simulation–based materials flow control system might be developed, a case study of a painted automotive mirror production system is given. It should be noted that at present no work has been conducted to create such a decision support system (beyond the simulation itself), this paper shall simply explore the possibilities of developing such a system.

Material Management in Decentralized Supply Chains

A supply chain is a network of facilities that performs the functions of procurement of material, transformation of material to intermediate and finished products, and distribution of finished products to customers. Often, organizational barriers between these facilities exist, and information flows can be restricted such that complete centralized control of material flows in a supply chain may not be feasible or desirable. Consequently, most companies use decentralized control in managing the different facilities at a supply chain. In this paper, we describe what manufacturing managers at Hewlett-Packard Company (HP) see as the needs for model support in managing material flows in their supply chains. These needs motivate our initial development of such a model for supply chains that are not under complete centralized control. We report on our experiences of applying such a model in a new product development project of the DeskJet printer supply chain at HP. Finally, we discuss avenues to develop better models, as well as to fully exploit the power of such models in application.

A model for implementing a paradigm of time-managed, material flow control in certain assembly systems

Abstract A paradigm for the time-managed control of material flow in job shop and small-lot environments which are subject to random disruptions is presented. The paradigm is implemented through a model which invokes certain special structures to investigate fundamental operating characteristics, including measures of kitting effectiveness. It is proven that schedules are most economically time-managed by co-ordinating vendor deliveries, rather than by deliberately delaying materials in-process. Fundamental results which permit scheduling and rescheduling are derived, along with certain performance measures necessary to time-managing flow effectively. Numerical tests indicate the accuracy of the model and demonstrate how material flows can be time-managed to minimize costs. The paradigm appears to be better suited than others for managing material flows in job shop and small-lot environments.

Control system of material flow in hot rolling-mill drive

The problem of forming and wind up loop in a bar, rod and profiles hot rolling mills is considered. A new conception for process forming and wind up loop are presented. Application of modern control theory has led to construction of simple special system (observer) in which of the basis of some state variable mensurations, torque load can be estimated. Also a simplified algorithm of material flow control are presented. The given algorithm structure enables preliminary determined by the range of limited and allowable parameters of rolling-mill line. The describe system are installed in an one rods, profiles and wire rolling-mill in Poland.

A GENERAL APPROACH FOR COORDINATING PRODUCTION IN MULTIPLE‐CELL MANUFACTURING SYSTEMS

We introduce a general approach to the coordination and control of material and information flow in multiple cell manufacturing systems. This approach uses production authorization cards (called PAC system) and generalizes such well‐known approaches as MRP (material requirements planning), KANBAN (japanese card system), OPT (optimized production technology), BSS (base. stock system), IC (integral control), CONWIP (constant work‐in‐process), and others. It provides a framework for developing coordination and control mechanisms that combine the desirable features of more than one of these traditional approaches. The coordination is achieved by the rules that determine when and how material and information flow through the system and by the appropriate choice of the parameters of these rules. We also discuss various models of the PAC system that can be used to gain insight into the impact of the choices of the parameters. Directions for future research in this area is also outlined.

Integrated decision making in a flexible assembly system: a new approach for operational control

Abstract The degree to which flexibility in product mix, flexibility in product routeing, and flexibility in buffer sequencing can influence manufacturing system performance is the focus of this paper. Of special interest is the performance of material flow control architectures which integrate these flexible control concepts. The manufacturing context is that of diverse mixed technology circuit boards assembled using a cellular approach. The research methodology is that of simulation using the SIMAN and FORTRAN languages. Results indicate that the incorporation of flexibility concepts into material flow architectures can significantly affect system performance, especially when properly integrated with other operational control mechanisms.

Push and pull in manufacturing and distribution systems

AbstractThe terms “push” and “pull” have been used to describe a wide variety of manufacturing and distribution environments. To some, the distinction refers to a specific attribute which can be identified by observing the mechanisms for controlling material flow on the factory floor. To others push and pull can be defined in terms of a specific policy for the management of inventories and production schedules. Finally there are skeptics who maintain that the push/pull dichotomy is a fiction created by academics or unscrupulous consultants to promote their latest theories or systems.In this paper, we review the various definitions of push and pull in operations literature. It is clear from this review that the attributes which distinguish pull systems from push systems are not well understood.The purpose of this paper is twofold. First, we clarify the meaning of push and pull in manufacturing and distribution systems. This clarification gives rise to a framework for push and pull that can serve as a classification scheme for material control systems. While we do not claim that our framework sufficiently classifies all material control systems, we demonstrate its application to a number of common systems. Thus, this framework can be used to analyze and compare management procedures for different classes of material control policies (such as MRP, kanban, base stock). This analysis is particularly useful to designers of material control systems, as well as those doing empirical research, who need to consider in depth various aspects of material control. Second, we intend to stimulate research efforts by the use of our framework. We demonstrate one such use of the framework by introducing a model of a particular integrated production‐distribution system. Our model represents a simple, three‐location, production‐distribution system with multiple products. We develop a system that is predominantly pull, and several systems with varying degrees of push. In the particular example we discuss, our pull system provides lower costs and higher service levels than the push systems.In developing our framework, we analyze material flow decisions in terms of four related decisions that can be used to distinguish push systems from pull systems: 1) batch size, 2) timing of a production or shipment request, 3) setting dispatch or allocation rules, and 4) the presence of interference mechanisms for expediting or handling of emergency orders. The first two decisions are primarily concerned with individual products or parts. The second two decisions introduce the added complexity of multiple products, locations and customers. For each decision, we examine the authority for the decision and the information content used in making the decision.We shall see that it is not possible or useful to label a manufacturing system as being entirely push or entirely pull. We argue that push and pull are characteristics of the underlying decision‐making process; and hence manufacturing control systems, which embody a collection of decisions, will contain elements of push or pull to varying degrees. Nevertheless, certain systems, containing such diverse elements often give the impression that they are predominantly one or the other. Our extended definitions provide a more complete picture that can be useful to researchers engaged in empirical work, as well as to managers concerned with system design.The paper is organized as follows: following an introduction and a review of various definitions of push and pull, we describe integrated production‐distribution systems. In the next section we present our framework for defining push and pull systems. Throughout this section we refer to commonly used planning and control systems, such as MRP, kanban, DRP, fair shares, and OPT. We then introduce a model that can be used to compare different material control systems. Finally, we present a summary and conclusions.

Decision support systems for management in central warehouses of building plants

A typical characteristic of building plants is the large number of building sites with temporary character. Therefore building plants often have got a central warehouse for building materials, especially material of interior of buildings with about 20,000 different items. The purpose of the central warehouse is the optimal management and control of material flow and information flow between suppliers of materials, central warehouse and buiIding sites in order to have the materials at the sites always in correct amount and good quality and to get the costs minimized. On different levels of the management of a central warehouse there are many non-structured and partial-structured decision processes that’s why modern computer-aided methods have to be developed and used, especially interactive decision support systems (DSS). The purpose of the paper is to represent a general survey of some problems of modelling, implemen~tion and appti~tion of the DSS for managing central warehouses of building plants. Details are demonstrated by [I].

Simulation helps tire manufacturer change from push to pull system in controlling material flow

Simulation helps tire manufacturer change from push to pull system in controlling material flow

LOGISTICS ACCORDING TO BULL

Michel Guérin joined Bull, the French computer company, at the end of 1985 as director of Material Flow Control with responsibility for the distribution logistics of mass‐market products. He was involved in the company's Cronos project from the beginning, and explains how Bull is succeeding in taking on the new forces in the market.

A systems approach to the implementation of JIT methodologies in Lucas Industries

Competitive modern manufacturing businesses must operate total materials flow control systems to ensure low stock levels and short lead times. When a variety of products is produced, to achieve just-in-time operation relevant to the overall business time-constants, composite control systems are needed within the factory, supported by matching supply processes and levelled output scheduling.

Material flow control in AGV/unit load based production lines

The use of automated guided vehicles (AGVs) as transporters and mobile workstations in automated assembly lines is on the increase. This is due in part to the flexibility AGVs introduce in the design of production lines. In this paper, models for the management and control of material flow through AGV based production lines are developed. The use of the models permits the line designer to optimally determine the launch times of successive unit loads of parts into the line to minimize production makespan while balancing between line idleness and the idleness of vehicles employed on the line. The use of the models for AGV based production line design purposes is demonstrated through example problems.

Recent Developments in the Automation of Steel Rolling

This paper deals with recent developments in the automation of steel rolling, i.e. the application of control theory to actual rolling processes, process control using a newly developed model, and systems of mill control, material flow control, quality control and the diagnosis of machine conditions.