Material Flow Pattern Research Articles

Forming minimum-cost machine cells with exceptional parts using zero-one integer programming

The value of forming machine cells for efficient job shop operations is well recognized. In practice, machine cells have often been formed based on intuitive guidelines driven by business objectives. For example, the cell design may seek to match the required skills of operator teams to available personnel, simplify material flow patterns, relieve congested areas around key equipment, and minimize the effect of undesirable environmental factors (noise, vibration, heat, and so on). Traditional methods of cell design often use heuristic rules that involve production flow analysis, similarity coefficients, rank-order clustering, or graph-theoretic methods. A more academic approach is to describe the problem as minimizing a constrained objective function written in terms of cost. The cost-minimizing approach has an advantage in that its importance is naturally understood by upper management. However, this approach generally involves using zero-one integer programming (IP) and thus has had limited usage because the IP approach is computationally demanding and relatively inflexible because it does not allow a controlled number of intercellular movements. Recent studies have shown how to reduce the computational demands. This leaves the inflexibility of the IP approach as its major obstacle. The motivation for this research is to show a method for increasing the zero-one IP method's flexibility by removing its prohibition on intercellular operations while minimizing overall operating costs.

Design of cellular manufacturing systems in tandem configuration

This paper develops a cell formation approach for a class of cellular manufacturing systems in which intercell moves are restricted to flow in one direction from one cell to the cell immediately downstream, without backtracking. An optimal zero-one integer programming model is used to determine which machines and parts should be assigned to cells and to specify the relative position of the cells on the factory material flow pattern. The model subdivides, the underlying manufacturing system into cells based on an intercell traffic minimization criterion and subject to machine capacity and operations sequence constraints. The model also considers part setup and run times for the evaluation of capacity requirements.

アルミニウム合金円柱のすえ込みにおける潤滑の効果

A concentric circular groove is on the both end surfaces of aluminum alloy column to retain lubricant. The columns are compressed by appling lubricant oozed from a groove and its barreling forms are measured. Effects of diameter and depth of concentric groove on the lubricating ability are studied in the compressibility of 10 to 40%. Effective geometric conditions of a groove are obtained from these experiments. Material flow patterns in the cross section of compressed columns with a concentric groove is shown in the comparison with a compressed column without a groove.

Subsurface deformation patterns around indentations in work-hardened mild steel

Abstract By using specially prepared specimens of work-hardened mild steel, subsurface deformation patterns around Vickers, conical and spherical indentations of millimetre dimensions have been determined. It has been shown that in no case does the deformation pattern agree with the predictions of the plasticity theory for a rigid-perfectly plastic material; the material flow pattern is also inconsistent with the radial flow models. Also, plastic natural strains of 2±0·01 and 41±0·001 have been estimated at the tips of a Vickers and a conical (included angle, 45°) indentations respectively. In the case of a spherical indentation of size a/R = 0·5, where a and R are the radii of contact and the indenter, respectively, the plastic natural strains are estimated to be 0·1 ±0·05 and 0·15±0·06 at z/a = 0·5 and 0·65 respectively, where z is the distance measured from the undeformed surface along the load axis.

Reorganisation of material flow for natural grouped assembly work – some principles and results from action research

The process of change in the final assembly plants in the Swedish vehicle industry consists partly of an endeavour to develop alternatives to the traditional line systems, thereby increasing the differences between various assembly processes. The development of production systems for long cycle time assembly work demands changes in the product and process structures. In these production systems, which are based on functional wholes instead of additive component tasks, new descriptions of the product and the work are demanded in order, among other things, to make them surveyable. This paper reports some of the results from action research over a five–year period. I discuss principally the consequences of long cycle time assembly work on material flows and layout design. The results reported are: material flow patterns and space requirements; principles for and consequences of naturally grouped work in final assembly in highly parallelized production systems; the relationship between production planning, production control and naturally grouped work; the relationship between parallelization, buffer function and space requirements. The work has been carried out in collaboration with practitioners and in the majority of cases it has been possible to develop and apply results from earlier research in the development of new industrial layouts and production systems. I discuss a number of these basic principles in detail in the following.

Flow of Rubber Compounds in a Plasticating Unit of a Reciprocating-screw Injection Molding Machine

Abstract An experimental study of the distribution of material and internal flow patterns in the cold feed screw injection molding machine for rubber compounds is presented. Experimental studies are carried out by vulcanizing rubber compounds in the screw of the plasticating unit at various positions in the molding cycle. The screw is then removed and the rubber strip unwound from the flights. It is found that transverse flow patterns begin at the feed port and proceed down the channel. Various kinds of starvation behavior are observed especially at low back pressures and with narrow feed strips.

Galapagos Hot Spot‐SPreading Center System: 2. 87SR/86 SR and large ion lithophile element variations (85°W‐101°W)

Thirty eight samples of basalts dredged from the Galapagos spreading center (GSC) between 85°W and 101.5°W longitudes have been analyzed for K, Rb, Cs, Ba, and Sr contents as well as for 87Sr/86sr ratios. Basalts between 85°W and 89°W segment of the GSC range from 0.7025 to 0.7028 in 87Sr/86sr and those between 95.5°W and 101.5°W range from 0.7026 to 0.7027. These basalts are characterized by LREE‐depleted patterns. Basalts from 89°W to 95.5°W segment having slightly LREE‐depleted to LREE‐enriched patterns ((La/Sm)E.F. between 0.8 and 2.4) range from 0.7027 to 0.7031 in 87Sr/86Sr. The longitudinal 87Sr/86Sr variation shows a maximum at about 92°W, where the GSC is nearest to Darwin Island. The alkali and alkaline earth elements as well as several element ratios also show maxima in their longitudinal profiles, but these occur at about 91°W. The apparent shift of 87Sr/86Sr maximum with respect to that of the trace elements may be related to differences in the degree of partial melting. The highest 87Sr/86Sr from the GSC is only slightly lower than the highest 87Sr/86Sr for tholeiitic basalts from the Galapagos Archipelago. Several possible hypotheses have been examined to account for these geochemical and Sr isotopic variations. In the light of the presently available data, the most promising explanation seems to be a binary mixing of hot spot (or plume‐type) material with the source of ‘normal’ mid‐ocean ridge basalts and resulting rift propagation. Both end‐members seem to be heterogeneous, and therefore it is at present difficult to put severe constraints on this binary mixing. Nevertheless, the flow pattern of mantle material from the hot spot does not appear to be radial but is preferentially channeled along the 91°W and 92.5°W fracture zones toward the rift.

GEMS: A generalized manufacturing simulator

The purpose of this paper is to describe a Generalized Manufacturing Simulator (GEMS) which can be used in the analysis of complex discrete part manufacturing systems. GEMS is a FORTRAN based analysis program which has been developed to study assembly line or job shop manufacturing environments. However, the current capabilities of GEMS enable a user to model a wide range of industrial, social, and operational problems. Conceptualization of manufacturing environments to the GEMS program is executed via a box/node arc network representation of the manufacturing system. GEMS is an activity-on box (node) simulation program composed of standardized simulation input via specialized boxes and arcs. A box (node)/arc structure can be developed to represent complex material flow patterns, probabilistics branching, routing based on attribute values, resource constraints, cost considerations, and complex queueing characteristics. GEMS can be used to study product flow rates, manufacturing capabilities, and queueing phenomena; assess in-process inventories and raw material storage requirements; determine the effects of alternate sequencing and scheduling rules; different routing and material handling schemes; and the impact of limited resources and increased/decreased production rates. An analysis package has been constructed which normally requires only a representation of the simulated system in terms of a network diagram, and transmission of this diagram to the GEMS program structure through FORTRAN NAMELIST data inputs.

Flow Pattern of Material in Plasticine Model Billets : 1st Report, Fundamental Study on Helical Rolling Process

Flow Pattern of Material in Plasticine Model Billets : 1st Report, Fundamental Study on Helical Rolling Process

Theoretical Analysis of the Formation of Glacial Flutes

Abstract In an analysis of the formation of flutes by subglacial cavities the flute-forming sediment is treated as a linear isotropic elastic material prior to failure, which occurs when Coulomb's law is satisfied. The maximum height of a flute is derived as a function of the mechanical properties of its material and the factors controlling the variation of height with distance along the flute are analysed. The flow pattern of material during the formation of a flute which the theory suggests is similar to the patterns which have been determined in a till fabric analysis of flutes near Breiðamcrkurjökull, Iceland.

Functional Components of the Ferrous Scrap Industry in a Selected Portion of the Southeastern U. S.

In recent years, new electric steel mills have been built and total electric steel mill production has increased substantially in the south- eastern United States. For several years, the Southeast has been an excess producer of ferrous scrap—the basic raw material used in electric steel mill production. (1) Ferrous scrap, particularly scrap steel, can be used in varying quantities in all types of steel-making furnaces: the open-hearth, electric, basic oxygen (BOF), and Bessemer. Only electric- arc steel-making furnaces, however, are currently used in the area con- sidered by this paper, and they are charged almost exclusively with steel scrap. Electric furnace steel producers depend almost exclusively on the scrap industry for their basic raw material. Purchased scrap con- sumption for electric mills ranges from 75 to 100 percent of the total scrap consumed, depending on whether or not mill-revert scrap is con- sidered as a separate source. Cast iron is not purchased or consumed by steel mills. For the most part, it is bought and used by large foundries located in the Birmingham-Anniston, Alabama, area. STUDY AREA. This paper focuses on the functional components of the ferrous scrap industry currently providing essential raw materials for five electric steel mills located in three Southeastern states. These five steel producers are located in a relatively compact geographical area within Georgia, South Carolina, and North Carolina. Since all five mills are electric, they are dependent on ferrous scrap as a raw material. The outer boundary of their collective raw materials supply area thus serves

Elimination of Vibrations in an Ore Unloading Bin

Problems of undesirable vibrations in an ore unloading structure are described. Earlier unsuccessful attempts to eliminate vibrations by changing allegedly exciting frequencies mechanically and by increasing natural frequencies structurally are cited. Scientific evaluations of granular material flow patterns in the bin are presented, which identify possible causes of and methods to alleviate the vibrations. Finally, the corrective measures in flow control taken to eliminate vibrations are illustrated.

Applications of Rheology to Rubber Processing

Abstract Recent years have seen great advances in the general field of polymer processing; these have been to a large extent connected with the very rapid growth of the thermoplastics industry, particularly polyolefins, nylon, and dacron (terylene). Because these latter materials have been simple (pure) polymers, usually used without plastizers or other additives, and relatively stable at and just above their ‘melt’ points, they could be treated theoretically as uniform materials, with well defined physical properties. However, variation of molecular weight, molecular weight distribution, and chain branching within a given type of polymer causes physical properties to vary with the method of synthesis, even from batch to batch, and so tabulation of the numerical values of these properties has been a laborious and expensive business. Nevertheless the very fact that such properties were largely unaffected by melt processing operations (particularly for the earliest of the polyolefins, low-density polyethylene) encouraged engineers, physicists and technologists to analyze and predict the flow behavior of these materials during processing. On the one hand there has been a growing interest in the results of modern theoretical rheology, and in the extent to which they can be used to investigate the rheological properties of polymer melts by experimental means; this work has been based both on concepts of material structure, the molecular approach, and on strictly mathematical ideas, the continuum approach; it has led in most cases to idealized mechanical (or mathematical) models of rheological behavior, using as few material parameters (or parametric functions) as possible, consistent with a model behavior approximating that of commonly used materials. On the other hand, efforts have been made to apply the methods of traditional Newtonian fluid dynamics to analyse material flow patterns in relatively complicated situations, such as occur in actual processing operations. In general, the models used for thermoplastic melts in this latter context have been a good deal simpler than those known to be needed from general rheological experiments, while quite simple, but generally realistic, models prove intractable in complex situations. Attention has therefore been directed to approximate methods, which use whatever information is available ab initio about a particular situation to simplify the equations used to describe the situation. As an example, in the manufacture of three mil sheet by calendering, one realizes at once that the thickness of the sheet is small compared with its other dimensions, and also compared with the roll diameters. This allows lubrication theory to be employed. Such techniques, though not easy to describe fully, are highly important because of their power. They have always been used in physics and engineering, often unconsciously when little was known about the behavior of materials, and usually in isolation. They depend on our being able, when studying a particular flow pattern, to reject much of the complex rheological information available about a material because much of it proves irrelevant; in consequence, we are led to make just those rheological measurements that are necessary to understand the flow in question.