Showing papers on "Material flow published in 1992"

Supply Chain Dynamics—The Change Engineering Challenge of the Mid 1990s

Abstract: Much has been written concerning the supply chain demand amplification problem, best described by the ‘law of industrial dynamics’. Broadly speaking, if a supply chain can find a way to fluctuate, it will.The paper defines supply chains and reviews their current state of development. By way of a simulation example, the importance of good, shared, information flow is highlighted, as are several other strategies that lie more within the control of individual businesses. Good supply chain operation requires adequate design, led by a product champion committed to systems change. Persuasive evidence to support the product champion is therefore offered. Examples include internally generated demand amplification caused by human schedulers; an industrial supply chain case history; supply chain redesign via simulation; and a review of a proposed effectiveness framework which offers the possibility of integrating both modelling and design phases.The methodologies that are described herein may be universally applied...

Material Flow in Electronic Product Based Supply Chains

Abstract: A review of electronics product based supply chains is presented. This naturally leads to the development of a “reference framework” for electronic products supply chains. It is used as a foundation for the analysis of a typical supply chain for a personal computer. Attention is focused on the published dynamic behavior associated with the electronic components echelon. The shortage/surplus behavior characteristic of the echelon and exemplified by the “bookings‐to‐billings” ratio is explained using a causal loop model. A pragmatic approach to the reduction in on‐costs achieved by redesign is presented and illustrated by comparing the relative merits of a number of suggested improvement strategies. Many of the features highlighted are applicable to the majority of electronic product supply chains; particularly the prominent role of multinational companies and the global nature of material supply. The establishment of much improved buyer‐supplier relationships is seen as an essential component in achieving improved supply chain design and operations.

Compression molding simulation of chopped fiber reinforced polymeric composites in plate‐rib type geometry

Abstract: A study on anisotropic material flow of polymeric composites in compression molding was conducted. Flow resistance and material anisotropy were measured by compression and tension tests to quantify the inhomogeneity of chopped fiber reinforced polymeric composites. The material was assumed to obey Hill's anisotropic yield criterion with its associated flow rule. An anisotropic finite element formulation was developed to simulate the material flow under various conditions. This two-dimensional model was applied to plane strain compression in a mold with plate-rib type geometry to substantiate the effect of fiber induced anisotropy. The predictions were compared with experimental results.

Improving the Fatigue Resistance Of Cold Forging Tools by Fe Simulation and Computer Aided Die Shape Optimization

Abstract: It is the intention of the present article to point out a new method for computer aided tool optimization as part of computer integrated tool manufacturing. Based on the results of finite element (FE) analysis and subsequent tool failure simulation, it is possible to optimize the FE model of a tool already at the stage of construction, in order to enhance the service life and process reliability. The permissible degree of freedom for any shape correction, of course, is mainly limited by constructive constraints of the tool and the properties of the material flow during the extrusion process. Thus the resulting optimized geometry has to he considered as a possible constructive alternative. However, analytical as well as practical solutions already show that a parabolical or elliptical curved surface contour, replacing a regular radius, not only improves the fatigue resistance but may have a positive influence on material flow behaviour, friction forces and resulting tool loads as well (1).The influence imp...

The use of MRP and LRP in a stochastic environment

Abstract: In a multi-echelon production/inventory system the material flow between successive stages has to be coordinated. A number of concepts are available for this material co ordination. Material requirements planning (MRP) is a well-known example. Unfortunately, the MRP concept also has a number of disadvantages. Especially in a stochastic environment, the MRP concept is not very efficient. An alternative concept for material co-ordination will be introduced and evaluated.

Computer simulation of material flow induced by thermal deformation in phase-change recording films

Abstract: Thermal deformation is calculated to clarify the cause of material flow due to multiple overwriting in a phase-change optical disk. The results suggest that the molten material of the recording layer moves along the recording track by thermal deformation of layers. Moreover, the direction of the material flow depends on the Al reflective layer thickness.

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.

Modular approach for Petri-net modeling of flexible manufacturing systems adaptable to various task-flow requirement

Abstract: A modular approach is presented for constructing Petri-net models for a class of flexible manufacturing systems (FMSs) composed of a transportation vehicle and several functional groups of entities such as machines and buffers. The resulting model preserves the geometric characteristics of the transportation subsystem as well as the flexibility of alternative routes for material flow in an FMS. By separating the machine-dependent part from the whole system, the final model in a modular structure is adaptable to various task flow requirements. In addition, the methodology can deal conveniently with a reconfiguration of the transportation layout. >

Method and a press for compressing material having two opposed transfer elements exacting a greater pressing force on the material during a forward motion than the pressing force exerted during a return motion

Abstract: A method and press for pressing material by way of feeding the material into a gap formed between two pressing surfaces, in which gap the cross section of the material flow is tapered in the forward transfer direction of the material. The material is pressed between pressing surfaces formed by parallel, beam-shaped transfer elements which are reciprocatingly moved in the direction of material flow in two alternating groups so that the mutually opposed transfer elements of both pressing surfaces are moved in a mutually synchronized manner in the same direction. During the forward transfer motion the pressing force exerted by the transfer elements on the material is greater than the pressing force exerted during the return motion of the transfer elements.

A method and a press for compressing material

Abstract: A method and press for pressing material (11) by way of feeding the material into a gap formed between two pressing surfaces (1, 2; 1', 2'), in which gap the cross section of the material flow is tapered in the forward transfer direction of the material. The material is pressed between pressing surfaces formed by parallel, beam-shaped transfer elements (1, 2; 1', 2') which are reciprocatingly moved in the direction of material flow in two alternating groups so that the mutually opposed transfer elements (1, 1' and 2, 2') of both pressing surfaces are moved in a mutually synchronized manner in the same direction. During the forward transfer motion the pressing force exerted by the transfer elements on the material (11) is greater than the pressing force exerted during the return motion of the transfer elements.

The Operation of Manufacturing Systems

Abstract: The operation of a manufacturing system is the complex task of planning the material and information flows in the system. Proper material flow is what enables a manufacturing system to produce products on time and in sufficient quantity. It is a direct consequence of the system’s information flows: command information from human planners or from planning software presribes the material flow in the system, while sensory information about the status of the system’s resources is used to decide on the appropriate commands. The fundamental activity in the operation of a manufacturing system is thus determining the commands which prescribe the material flow in the system.

A study of material flow systems (input/output) in high-bay warehouses

Abstract: A method of planning and designing product sorting systems in warehousing is described. The theoretical background of the analytical models and simulation modelling is given. A calculation of the capacity of elements for joining and dividing for different priorities of material flow is described. New parameters are introduced in the formula for calculating the average number of unit loads in a system for joining, in the direction of the slave flow and for a simple analytical model for joining material flows with two different priorities with an exponential distribution of inter-arrival time. Simulation results are obtained using the GPSS/FON simulation language. Some characteristic results, used in the process of planning and design of two new distribution centres in Belgrade, are shown.

Process and apparatus for treating bulk material.

Abstract: With a process and an apparatus for treating bulk material, a solution is to be produced, with which bulk material can be subjected to the most varied treatment stages in continuous operation without the conveying continuity being interrupted, it being intended that a corresponding apparatus be capable of very compact design with identically high throughput capacity. This is achieved in terms of the process in that all treatment stages are carried out in part zones on a continuous bulk material flow, the bulk material flow being formed as a horizontal flat travelling layer by rotary vibrating conveying, the apparatus being characterised in that, seen in the conveying direction (15) of the bulk material (18), each vibrating plate (4) is divided into part zones (11) adapted to the necessary treatment stages.

On Optimization of Dynamical Material Flow Systems Using Simulation

Abstract: Up until now risk analysis, as a rule, ended with the estimation of the risks. Further improvements -- optimal design, risk control, dynamic risk management -- require many more efforts. Essential difficulties are connected with the discontinuous or nonsmooth behavior of performance functions with respect to the control and (or) random parameters due to possible failures of the system's parts. Usually, the systems also include discrete event elements -- logical rules can change the structure of the system if some constraints are not satisfied, for example safety constraints. These problems require new formal analysis tools which will include dynamics, stochastics, nonsmoothness and discontinuity. In this paper, the authors consider a simple example of such a problem with the aim to explore the possibilities for its analysis. The problem is comprised of optimizing a material flow system based on an efficient use of simulation. The material flow system may be a production system, a distribution system or a pollutant-deposit/removal system. The important characteristic which is considered in this paper is that one of the components of the dynamic system is unreliable. This characteristic leads to simulation models in which criteria are discontinuous with respect to the optimization parameters. This makes it difficult to use the standard methods for the estimation of gradients of the expected criteria values. A method is introduced which overcomes the difficulty. From a formal point of view the problem can be viewed as a mixed integer stochastic optimization problem.

Hot extrusion pipe making method of outside surface deformed pipe

Abstract: PURPOSE:To improve dimensional accuracy heating the corresponding part of a billet where the amt. of the material flow into a die hole is small to a temp. higher than in the other parts in hot extrusion of an outside surface deformed pipe. CONSTITUTION:The billet to be supplied into the die 2 is extruded by heating the corresponding part thereof where the amt. of the material flow into the die hole 2a is small to the temp. higher than in the part where the amt. of the material flow into the die hole 2a is large. Further, the die larger in the approach angle alpha of the corresponding part where the amt. of the material flow into the die hole 2a is small than the corresponding part where the amt. of the material flow is large is used at need. The dimensional accuracy of the outside surface deformed pipe is improved in this way and the yield of production is improved.

Flow Characteristics of Compression Molded Stampable Sheet with Rib Part

Abstract: Moldings using stampable sheet of long fiber reinforced thermoplastics are produced by material flow under compression molding. Generally, ribs are incorporated into the moldings to increase the stiffness of the components. Unfortunately, the fibers are often unable to fill the ribs due to the long fiber lengths and the Stampable sheet parts cannot be effectively stiffened. In this study, the influence of die design on material flow during compression molding were examined. The material flow of each layer was observed by photographing vertical sections and taking soft X-ray photographs. An image processing system was then used to measure the fiber flow length into the rib section. These studies revealed resin exudation during the compression molding process. The fiber flow length into rib section was enhanced by using a die with a large fillet radius. Key Word : Long fiber reinforced thermoplastics/Stampable sheet/Compression molding/Material flow

Flow brake for supply of loose bulk material - has closed brake screen fixed on shaft to build-up material until it smoothly overflows

Abstract: The brake for the material flow comprises a housing (2) with an inlet (1) and in the middle a full-length rotatable shaft (6) on which a brake screen (9) is fixed. This brake screen has a leaning angle (8) of between 10 and 30 degrees and underneath the screen there is a frusto-conical outlet (4). An overflow edge (3) is preferably mounted on the brake screen at the end to form with the housing an overflow (7). The loose material falling through the inlet passes onto the brake screen which has opening so that the material builds up. It forms a material buffer corresponding to the size of the screen. Further supply of material passes over the overflow edge to the outlet. ADVANTAGE - A smoother supply of material.

Press forming die for drawing

Abstract: PURPOSE:To make the deep drawing possible without generating cracks on the material to be worked even if there is a directional property on the flow of the material by setting the rotating mechanism to rotate the punch with the head formed to the spherical shape to the flowing direction of the material. CONSTITUTION:The material 8 to be worked clamped with the drawing dies 7 and the blank holder 6 is applied with the drawing force by the spherical head 4a of the punch 4 and deformed with drawing. On this deforming case, the head 4a of the punch 4 rotates along the material flowing direction of the material 8 to be worked with the rotating mechanism, pulls the material from the desired direction with the frictional force of the contact surface of the punch 4 and the material 8 to be worked, or does not hinder the material flow, accordingly, the material flow is performed smoothly and sufficiently, so the generation of cracks on the material 8 to be worked is prevented, and the forming of deep drawing can be executed.

Extruder for multilayer plastics - has package of plates in molten material distribution units with different geometries to form flow channels

Abstract: The extrusion tool, to produce multi-layer bonded plastics material, has a molten material distribution unit formed by a number of templates of different geometry but identical outer dimensions. Their surfaces lie in a row against each other so that the plates with the same geometry form zones which form channels for the molten material and/or close the material flow. ADVANTAGE - The assembly allows rapid changes in the layers to be extruded and the structure of the extruded compound material.