DSpace at MIT
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Mostrando recursos 1 - 20 de 108
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Quality and Quantity Modeling of a Production Line - Kim, Jongyoon; Gershwin, Stanley B.
During the past three decades, the success of the Toyota Production System has spurred research in the area of manufacturing systems engineering. Two research fields, productivity and quality, have been extensively studied and reported separately both in the manufacturing systems research literature and the practitioner, but there is a lack of research in the intersection of these areas. In addition to that, most studies on the relationship among manufacturing system design, quality and productivity are based on anecdotal evidence or qualitative reasoning that lack sound scientific quantitative foundations. This study tries to establish a scientific foundation to investigate how production...
2.
A Base Stock Inventory Model for a Remanufacturable Product - Graves, Stephen C.
We report on an industrial project in which we developed an inventory model to provide decision support for the design and deployment of the field service support system for a remanufacturable product. The product was a dialysis unit for home use. Each unit that was installed in a home would eventually be removed due to failure, or the need for preventative maintenance, or the termination of the service. Upon removal, each unit was shipped to a central depot for re-manufacturing so that it could be returned to service. We develop a model to determine the inventory requirements at each regional...
3.
Characterization of Diamond-Like Film after Focused Ion Beam Processing - Fu, Yongqi; Ngoi, Kok Ann Bryan
Optical properties (transmission and refractive index) and chemical structure (XPS) of diamond-like coating (DLC) film before and after focused ion beam milling (FIBM) process, were investigated in this paper. It is shown by our FIBM experiment that influence of FIBM on Optical properties and chemical structure of the DLC film is not apparent, especially in near-infra region. The film still can be used for optical applications. As an application example, diffractive optical element (DOE) was directly fabricated on the film by use of FIBM. Measured diffraction efficiency of the DOE is 73%, which is acceptable for conventional use.
4.
Computer-aided Tooling Design for Manufacturing Processes - Nee, Andrew Y. C.
Tooling design for manufacturing processes refers to direct tooling for making a part such as molds and dies for injection molded parts and metal stampings, or for supporting machining operations such as jigs and fixtures. This paper summarizes some of the R&D activities in those areas over a period of 20 years in the Department of Mechanical Engineering, National University of Singapore. It is notable that increasing use of computer tools has turned what is used to be known as a â??black artâ?? into a discipline embracing both heuristic and scientific analyses.
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Droplet Bouncing Behavior in the Direct Solder Bumping Process - Hsiao, Wayne; Chun, Jung-Hoon
This paper presents the results of an ongoing effort to develop a direct solder bumping process for electronics packaging. The proposed process entails delivering molten droplets onto specific locations on electronic devices to form solder bumps. This study is focused on investigating droplet deposition behaviors that affect solder bump characteristics such as final bump volume, shape, and adhesion strength. The occurrence of droplet bouncing has a strong influence on these characteristics. The potential for a droplet to bounce in the absence of solidification was modeled in discrete stages based on energy conservation. Wetting and target surface roughness were identified as...
6.
Factory Models for Manufacturing Systems Engineering - Gershwin, Stanley B.
We review MIT research in manufacturing systems engineering, and we describe current and possible future research activities in this area. This includes advances in decomposition techniques, optimization, token-based control systems analysis, multiple part types, inspection location, data collection and several other topics.
7.
A Framework of Implementation of Collaborative Product Service in Virtual Enterprise - Ming, X.G.; Lu, Wen Feng
To satisfy new market requirements, manufacturing industry has shifted from mass production that takes advantage of the scale of production, to quality management that optimizes the internal enterprise functions, to e-manufacturing era that leverage intellectual capital via collaborative innovation. In the same time, the product itself is becoming the most important asset for sustainable business success. Consequently, the effectiveness, efficiency and innovation for the development of the product across the whole product lifecycle are becoming key business factors for manufacturing enterprise to obtain competitive advantages for survival. To tackle such challenges, a new business model called collaborative product services in...
8.
Framework to Manage Customer Enquiries for SMEs - Xiong, M.H.; Tor, Shu Beng; Bhatnagar, Rohit; Venkataramanaiah, S.
For most Smaller Manufacturing Enterprises (SMEs), how to manage customer enquiries at the customer enquiry stage is of great importance to maintain the competitive advantage and secure future customer orders. A lack of co-ordination between marketing/sales and production at this stage often leads to confirmed orders being delivered later than promised and/or being produced at a loss. In the paper, the problems and the solutions for managing customer enquiries faced by many SMEs are addressed. A general process for dealing with customer enquiries at the customer enquiry stage and a corresponding DSS approach are presented in detailed. The SMEs would...
9.
Functional Modeling in Conceptual Die Design - Tor, Shu Beng; Britton, G.A.; Zhang, W.Y.
The use of function has been recognized as an important part of the design process over last two decades, especially at the conceptual design stage, due to its critical role in determining the final productâ??s functionality. Although there are now some general methodologies dealing with functions or reasoning about functions, virtually no commercial CAD system can support conceptual design process due to their focus on geometrical modeling but not functional modeling. This paper presents a functional modeling approach to guide conceptual die design through functional reasoning steps including functional decomposition, functional supportive synthesis and function-structure mapping. The formed functional model...
10.
Gaussian Distribution Approximation for Localized Effects of Input Parameters - Rzepniewski, Adam K.; Hardt, David E.
In the application of cycle-to-cycle control to manufacturing processes, the model of the process reduces to a gain matrix and a pure delay. For a general multiple input â?? multiple output process, this matrix shows the degree of influence each input has on each output. For a system of high order, determining this gain matrix requires excessive numbers of experiments to be performed, and thus a simplified, but non-ideal form for the gain matrix must be developed. In this paper, the model takes the form of a Gaussian distribution with experimentally determined standard deviation and scaling coefficients. Discrete die sheet...
11.
A Generic Mechanism for Repairing Job Shop Schedules - Raheja, Amritpal Singh; Reddy, K. Rama Bhupal; Subramaniam, Velusamy
Reactive repair of a disrupted schedule is a better alternative to total rescheduling, as the latter is a time consuming process and also results in shop floor nervousness. The schedule repair heuristics reported in the literature generally address only machine breakdown. This paper presents a modified Affected Operations Rescheduling (mAOR) approach, which deals with many of the disruptions that are frequently encountered in a job shop. The repair of these disruptions has been decomposed into four generic repair actions that can be applied singularly or in combination. These generic repair actions are evaluated through a simulation study with the performance...
12.
Imaging at the Nano-scale: State of the Art and Advanced Techniques - Aumond, Bernardo D.; El Rifai, Osamah M.; Youcef-Toumi, Kamal
Surface characteristics such as topography and critical dimensions serve as important indicators of product quality and manufacturing process performance especially at the micrometer and the nanometer scales. This paper first reviews different technologies used for obtaining high precision 3-D images of surfaces, along with some selected applications. Atomic force microscopy (AFM) is one of such methods. These images are commonly distorted by convolution effects, which become more prominent when the sample surface contains high aspect ratio features. In addition, data artifacts can result from poor dynamic response of the instrument used. In order to achieve reliable data at high throughput,...
13.
A Mechanical Model for Erosion in Copper Chemical-Mechanical Polishing - Noh, Kyungyoon; Saka, Nannaji; Chun, Jung-Hoon
The Chemical-mechanical polishing (CMP) process is now widely employed in the ultralarge scale integration chip fabrication. Due to the continuous advances in semiconductor fabrication technology and decreasing sub-micron feature size, the characterization of erosion, which affects circuit performance and manufacturing throughput, has been an important issue in Cu CMP. In this paper, the erosion in Cu CMP is divided into two levels. The wafer-level and die-level erosion models were developed based on the material removal rates and the geometry of incoming wafers to the Cu CMP process, including the Cu interconnect area fraction, linewidth and Cu deposition thickness. Experiments were...
14.
A Model for Contingent Manpower Planning: Insights from a High Clock Speed Industry - Bhatnagar, Rohit; Venkataramanaiah, S.; Rajagopalan, Anand
Intense competitive pressures have led to compressed product life cycles and frequent introduction of new products. This creates demand volatility and a consequent pressure on manufacturing to meet this variable demand. In this paper we model the manpower planning issues for a computer manufacturer during the product introduction phase when a quick ramp-up of production to meet rapidly increasing demand is a key requirement. A mix of permanent and contingent workers with different skill sets is considered. Some important issues addressed in this research are (a) how to assign workers with different skills to maximize production (b) what is the...
15.
Multiple Input-Multiple Output Cycle-to-Cycle Control of Manufacturing Processes - Rzepniewski, Adam K.; Hardt, David E.
Cycle-to-cycle control is a method for using feedback to improve product quality for processes that are inaccessible within a single processing cycle. This limitation stems from the impossibility or the prohibitively high cost of placing sensors and actuators that could facilitate control during, or within, the process cycle. Our previous work introduced cycle to cycle control for single input-single output systems, and here it is extended to multiple input-multiple output systems. Gain selection, stability, and process noise amplification results are developed and compared with those obtained by previous researchers, showing good agreement. The limitation of imperfect knowledge of the plant...
16.
A new digital image correlation algorithm for whole-field displacement measurement - Su, C.; Anand, Lallit
We have developed a new digital image correlation (DIC) algorithm for non-contact, two-dimensional, whole-field displacement and strain measurement. Relative to existing algorithms, our algorithm substantially reduces the calculation expense by using neighborhood information while processing the data to determine the displacement field in a sub-region of interest. The new algorithm also uses higher-order interpolations of the displacement field, allowing for better accuracy in estimating strain distributions when the deformation field is non-homogeneous. Numerically-generated digital images are used to show that the new algorithm accurately reproduces the imposed displacement fields. The algorithm is also tested on actual images from deformed specimens...
17.
Optimal Capacity Adjustments for Supply Chain Control - Budiman, Benny
Decisions on capacity are often treated separately from those of production and inventory. In most situations, capacity issues are longer-term, so capacity-related decisions are considered strategic and thus not part of supply planning. This research focuses on optimal supply planning with emphasis on variable capacity to meet uncertain demand. It also defines three levels of capacity change: operating hours, labor availability and production hardware availability. The work presented here deals with the fundamental decisions to determine capacity, production, and inventory to meet customer demand while optimizing revenue and costs over a planning horizon (typically the life of the product). With...
18.
Optimizing Strategic Safety Stock Placement in Two-Layer Supply Chains - Lesnaia, Ekaterina
In this paper, we minimize the holding cost of the safety stock in the supply chain subject to linear constraints on the service times between the nodes of the network. In the problem, the objective function is concave as we assume the demand to be bounded by a concave function. The optimal solutions of the problem belong to the set of extreme points of the polyhedron, specified by the constraints of the problem. We first characterize the extreme points for the two-layer networks and then provide bounds to use in a branch and bound algorithm.
19.
Preliminary Results of InGaAsN/GaAs Quantum-well laser Diodes Emitting towards 1.3 µm - Wang, S.Z.; Yoon, Soon Fatt
GaAs-based nitride is found to be sensitive to growth conditions and ex-situ annealing processes. The critical thickness is almost one order thicker than the theoretical prediction by force balance model. The growth process could be sped up by the nitrogen incorporation itself, while the nitrogen incorporation could be affected by Beryllium doping. The incorporated nitrogen atoms partly occupy substitutional sites for Arsenic. Some nitrogen atoms are at interstitial sites. Annealing could drastically increase the optical quality of GaAs-based nitrides. As an end of this paper, some preliminary results of InGaAsN/GaAsN/AlGaAs laser diodes are also presented.
20.
A Rapidly Reconfigurable Robotics Workcell and Its Applictions for Tissue Engineering - Chen, I-Ming
This article describes the development of a component-based technology robot system that can be rapidly configured to perform a specific manufacturing task. The system is conceived with standard and inter-operable components including actuator modules, rigid link connectors and tools that can be assembled into robots with arbitrary geometry and degrees of freedom. The reconfigurable "plug-and-play" robot kinematic and dynamic modeling algorithms are developed. These algorithms are the basis for the control and simulation of reconfigurable robots. The concept of robot configuration optimization is introduced for the effective use of the rapidly reconfigurable robots. Control and communications of the workcell components...
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