An Improved Arcflow Model for the Skiving Stock Problem

Because of the sharp development of (commercial) MILP software and hardware components, pseudo-polynomial formulations have been established as a viable tool for solving cutting and packing problems in recent years. Constituting a natural (but independent) counterpart of the well-known cutting stock problem, the one-dimensional skiving stock problem (SSP) asks for the maximal number of large objects (specified by some threshold length) that can be obtained by recomposing a given inventory of smaller items. In this paper, we introduce a new arcflow formulation for the SSP applying the idea of reflected arcs. In particular, this new model is shown to possess significantly fewer variables as well as a better numerical performance compared to the standard arcflow formulation

Improved flow-based formulations for the skiving stock problem

Thanks to the rapidly advancing development of (commercial) MILP software and hardware components, pseudo-polynomial formulations have been established as a powerful tool for solving cutting and packing problems in recent years. In this paper, we focus on the one-dimensional skiving stock problem (SSP), where a given inventory of small items has to be recomposed to obtain a maximum number of larger objects, each satisfying a minimum threshold length. In the literature, different modeling approaches for the SSP have been proposed, and the standard flow-based formulation has turned out to lead to the best trade-off between efficiency and solution time. However, especially for instances of practically meaningful sizes, the resulting models involve very large numbers of variables and constraints, so that appropriate reduction techniques are required to decrease the numerical efforts. For that reason, this paper introduces two improved flow-based formulations for the skiving stock problem that are able to cope with much larger problem sizes. By means of extensive experiments, these new models are shown to possess significantly fewer variables as well as an average better computational performance compared to the standard arcflow formulation

A FUNCTION-BASED APPROACH TO ESTABLISHING STANDARDIZATION AND FLEXIBLE WORK CELLS FOR HIGH-VARIETY, LOW-VOLUME MANUFACTURING

Certain types of high-variety, low-volume manufacturing operations employ clusters of machines to execute general classes of operations in the manufacture of their product mix, but those operations differ significantly from job to job. Consequently operations are not standardized and batch and queue operational strategies are employed with all attendant shortcomings. However, closer examination reveals that these operations largely consist of a small number of elemental machine functions that are exercised in various combinations. The functions provide a basis to for defining richly descriptive standardized work at the individual process level using parameters to distinguish the unique settings and characteristics for processing a given job. Moreover, it appears the pareto principle applies to functional sequences, and high frequency sequences can be used to establish system level production engineering issues, including facility layout, process interfacing, and cellular standard work routines that achieve flow and labor balance in a flexible manner for the majority of products. This approach is demonstrated using and industrial case study

PENYELESAIAN MASALAH CUTTING STOCK DENGAN PENGELASAN MENGGUNAKAN TEKNIK COLUMN GENERATION

ABSTRAK Masalah cutting stock dengan pengelasan adalah permasalahan pemotongan dan pengelasan sejumlah bahan baku menjadi pola-pola tertentu untuk memenuhi permintaan dengan bahan baku sesedikit mungkin. Pada penelitian ini, masalah cutting stock dengan pengelasan diselesaikan dengan menggunakan teknik column generation. Teknik column generation memuat dua model, yaitu model master dan submodel pembangkit kolom. Model master adalah model linear programming untuk menentukan banyaknya bahan baku minimum yang diperlukan untuk memenuhi permintaan. Submodel pembangkit kolom berjutuan untuk membentuk pola baru yang akan dimuat pada model master. Pembangkitan kolom selesai dilakukan ketika solusi dari model master sudah tidak dapat memberikan solusi yang lebih baik dari solusi pada tahapan sebelumnya. Karena teknik column generation tidak selalu menghasilkan solusi bilangan bulat, maka dibangun model tambahan mixed integer programming untuk memenuhi permintaan yang belum terpenuhi. Hasil implementasikan menunjukkan bahwa teknik column generation dapat menyelesaikan masalah cutting stock dengan pengelasan dan mampu memberikan solusi optimal. Kata Kunci: linear programming, integer programming, column generation, permasalah cutting stock dengan pengelasan.   ABSTRACT The cutting stock problem with welding is a problem for cutting a number of raw materials into a number of cutting patterns to meet every demand such that the raw material needed is minimum. In this study, column generation techniques are used to solve the problem. The technique contains two models i.e the master model and the column generator submodel. The master model is a linear programming model that is used to determine the minimum number of raw material needed to meet the needs according the cutting patterns. The submodel is constructed to generate a new cutting pattern that will improve the optimal solution of the master model. The column generation step is complete if there is no cutting pattern that can give the better solution. Since column generation technique does not always produce integer solutions, an additional mixed integer programming model is needed to meet unmet demands. The computationl results show that column generation techniques can solve cutting stock problems with welding, and it can give an optimal solution. Keywords: linear programming, integer programming, column generation, cutting stock problems with welding

“Automation” of manufacturing in the late nineteenth century: the hand and machine labor study

Recent advances in artificial intelligence and robotics have generated a robust debate about the future of work. An analogous debate occurred in the late nineteenth century when mechanization first transformed manufacturing. We analyze an extraordinary dataset from the late nineteenth century, the Hand and Machine Labor study carried out by the US Department of Labor in the mid-1890s. We focus on transitions at the task level from hand to machine production, and on the impact of inanimate power, especially of steam power, on labor productivity. Our analysis sheds light on the ability of modern task-based models to account for the effects of historical mechanization.Published versio

A high resolution electro-mechanical actuator for automated skiving

This thesis describes a step by step approach to the design, assembly and final testing of a high resolution electro-mechanical actuator which will be an integral part of an automated skiving process used in the shoe manufacturing industry. It is referred to as a skiving machine in this thesis. The thesis provides the necessary background information as to the reasons for replacing a previous machine and then investigates the features considered suitable for incorporation into the new skiving machine. An investigation is carried" out into the desired objectives of the new design and the components to be used. A discussion then follows into the most desirable design systems to be considered for the skiving machine. It is concluded that a system comprising, of- actuating pins, levers, transmission wires and,, solenoids has the most ' appropriate combination of I, characteristics for a satisfactory machine, a' detailed description of the completed design and its parameters is given in relation to the initial objectives. There follows a description of the manufacture' and assembly based upon the design principles. The thesis then describes the performance of the machine and evaluates its skiving capability. Finally, suggestions for future improvements and further integration of the automation process in shoe manufacturing are made

Piece rate setting methods in the New England shoe industry

Thesis (M.B.A.)--Boston Universit