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Studies on the Process Parameters of Rapid Prototyping Technique (Stereolithography) for the Betterment of Part Quality  [PDF]
Raju Bangalore Singe Gowda,Chandra Sekhar Udayagiri,Drakshayani Doulat Narendra
International Journal of Manufacturing Engineering , 2014, DOI: 10.1155/2014/804705
Abstract: Rapid prototyping (RP) has evolved as frontier technology in the recent times, which allows direct transformation of CAD files into functional prototypes where it tremendously reduces the lead time to produce physical prototypes necessary for design verification, fit, and functional analysis by generating the prototypes directly from the CAD data. Part quality in the rapid prototyping process is a function of build parameters such as hatch cure depth, layer thickness, orientation, and hatch spacing. Thus an attempt was made to identify, study, and optimize the process parameters governing the system which are related to part characteristics using Taguchi experimental design techniques quality. The part characteristics can be divided into physical part and mechanical part characteristics. The physical characteristics are surface finish, dimensional accuracy, distortion, layer thickness, hatch cure, and hatch file, whereas mechanical characteristics are flexural strength, ultimate tensile strength, and impact strength. Thus, this paper proposes to characterize the influence of the physical build parameters over the part quality. An L9 orthogonal array was designed with the minimum number of experimental runs with desired parameter settings and also by analysis tools such as ANOVA (analysis of variance). Establishment of experimentally verified correlations between the physical part characteristics and mechanical part characteristics to obtain an optimal process parameter level for betterment of part quality is obtained. The process model obtained by the empirical relation can be used to determine the strength of the prototype for the given set of parameters that shows the dependency of strength, which are essential for designers and RP machine users. 1. Introduction Due to the advances in electronics and computers, there has been a significant growth in communication, information technology, and worldwide networking, which leads to globalization and opening of markets [1, 2]. Thus in product development, rapid prototyping (RP) and rapid product development have turned out to be the key instruments to save time and money with respect to the development of innovative products [2, 3]. Stereolithography (SLA) is one of the RP techniques, which involve fabrication of intricate shape of a plastic monomer directly from computer aided design (CAD) data by depositing material layer by layer by photopolymerization process [4]. The SLA process involves the following steps: conversion of the CAD model to the standard triangulation language (STL) file format; slicing
Dimensional accuracy of the skull models produced by rapid prototyping technology using stereolithography apparatus
A. Nizam,R.N. Gopal,L. Naing,A.B. Hakim
Archives of Orofacial Sciences , 2006,
Abstract: The purpose of this study was to determine the dimensional accuracy of the skull models produced by rapid prototyping technology using stereolithography apparatus. Computed tomography images were captured from four dry normal adult human skulls. The resultant 2-D images were stored in Digital Imaging and Communications in Medicine (DICOM) format. The segmentation of the images was prepared in MIMICS software. The slice files were then exported to a stereolithography apparatus (SLA) to produce the replica of each skull. Eight linear measurements were repeatedly made between identified landmarks on each of the original skull and its replica model using an electronic digital calliper. Each of the linear measurements was repeated 5 times and the average was taken to determine the absolute difference and percent difference between the original skull and its replica model. The overall absolute difference between the four human adult skulls and its replica models was 0.23 mm with a standard deviation of 1.37 mm. The percent difference was 0.08% with a standard deviation of 1.25%. The degree of error established by this system seems affordable in clinical applications when these models are used in the field of dental surgery for surgical treatment planning.
Critical Parameters Effecting the Rapid Prototyping Surface Finish
Journal of Mechanical Engineering and Automation , 2011, DOI: 10.5923/j.jmea.20110101.03
Abstract: A component can be manufactured in several ways. Rapid Prototyping technique is one among the material adding manufacturing process, building up its unique potential in the present scenario. This technique helps manufacture a product from the basic design of the component, thus optimizing the iterative product development process time and creating geometrically complex parts to precise dimensions. In the Rapid Prototyping process, surface finish is critical as it can affect the part accuracy, reduce the post-processing costs and improve the functionality of the parts. This paper presents an experimental design technique for determining the optimal surface finish of a part built by varying Build Orientation, Layer Thickness and keeping other parameters constant using the Fused Deposition Modeling (FDM) process. The design investigates the effect of these parameters on the surface finish. Experiments were conducted using a fractional factorial design with two levels for Layer Thickness and three levels for Build Orientation factor. The results are statistically analyzed to determine the significant factors and their interactions. The significant factors, their interactions and the optimum settings are proposed.
Rapid manufacturing and rapid tooling of polymer miniaturized parts using Stereolithography
Salmoria, Gean Vitor;Lafratta, Fernando H.;Biava, Matheus M.;Ahrens, Carlos Henrique;Ferreira, Pedro Z.;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2008, DOI: 10.1590/S1678-58782008000100002
Abstract: currently, miniaturization is a major trend in the manufacturing and commercialization of new industrial products. when small-sized objects should be manufactured with dimensions of only a few millimeters or less, many difficulties can appear using traditional processes. an alternative to study these new requirements is through the use of rapid prototyping technologies. stereolithography (sl) has established itself as one of the most popular and reliable process allowing the rapid manufacturing of complex parts. this paper investigates the sl process, which directly produces small parts by rapid manufacturing, and also indirectly by rapid tooling. the processability of small parts was investigated using two different shapes. the pom and abs materials were used in the indirect manufacturing. the dimensional accuracy, precision and tolerance of micro parts were evaluated using metrological techniques. results showed accuracy and precision greater than 97% when small-parts are manufactured directly by stereolithography.
Aplication of the stereolithography technique in complex spine surgery
Paiva, Wellingson Silva;Amorim, Robson;Bezerra, Douglas Alexandre Fran?a;Masini, Marcos;
Arquivos de Neuro-Psiquiatria , 2007, DOI: 10.1590/S0004-282X2007000300015
Abstract: many techniques have been proposed for surgical training as a learning process for young surgeons or for the simulation of complex procedures. stereolithograpfy, a rapid prototyping technique, has been presented recently as an option for these purposes. we describe the case of a 12 years old boy, diagnosed with ewing′s sarcoma in the cervical spine. after a surgical simulation accomplished in the prototype, built by stereolithography, the patient was submitted to a c4 corpectomy and to a c4 and c3 laminectomy with anterior and posterior fixation, a non intercurrence procedure. this technique is an innovative and complementary tool in diagnosis and therapy. as a result, it is easier for the surgeon to understand the complexity of the case and plan the approach before any surgical procedure.
A statistical approach to determining the uncertainty of peat thickness
J. Torppa
Mires and Peat , 2011,
Abstract: This paper presents statistical studies of peat thickness to define its expected maximum variation ( dm( r)) as a function of separation distance Δr. The aim was to provide an estimate of the observational uncertainty in peat depth due to positioning error, and the prediction uncertainty of the computed model. The data were GPS position and ground penetrating radar depth measurements of six mires in different parts of Finland. The calculated observational uncertainty for Finnish mires in general caused, for example, by a 20 m positioning error, is 43 cm in depth with 95 % confidence. The peat depth statistics differed among the six mires, and it is recommended that the mire specific function dm( r) is defined for each individual mire to obtain the best estimate of observational uncertainty. Knowledge of the observational error and function dm( r) should be used in peat depth modelling for defining the uncertainty of depth predictions.
The Sagittal Pelvic Thickness: A Determining Parameter for the Regulation of the Sagittal Spinopelvic Balance  [PDF]
Legaye Jean
ISRN Anatomy , 2013, DOI: 10.5402/2013/364068
Abstract: Objective. To propose and validate a dimensional parameter, the sagittal pelvic thickness (SPT) (distance between the middle point of the upper sacral plate and the femoral heads axis, expressed as a ratio with the length of the upper plate of S1: (SPT/S1) for the analysis of the sagittal balance of the pelvispinal unit. Methods. The parameters were analysed on standing radiographic imaging and compared for normal, low back pain, children, and spondylolysis cases. Results. Values of SPT/S1 were observed significantly higher in high grade spondylolysis populations and in children (3,5 and 3,7) than in normal population (3,3). A geometrical connection with the classical angular parameters validated SPT/S1. Conclusion. SPT/S1 was considered reflecting the lever arm of action of spinopelvic muscles and ligaments and describing the ability of a subject to compensate a sagittal unbalance. It was proposed as an anatomical and functional pelvic parameter. 1. Introduction A strict relation was described between the sagittal pelvic anatomy and the sagittal shape of the spine, particularly the amount of lordosis needed for each individual. Therefore, angular parameters were recommended because they are usable disregarding the size of the subjects [1–5]. In the same way, the distinction was established a long time ago by morphologists and paleontologists between the “pelvis in tension” of the quadrupeds and the “pelvis in pressure” characterizing the bipedalism [6]. They were distinguished according to their more or less lengthened form, defined by the distance between the upper sacral plate and the coxofemoral joints: the sagittal pelvic thickness (SPT). In spite of characterizing the sagittal pelvic anatomy as well as, angular parameters, SPT was poorly studied. By a radiographic study, we investigated here its significance on the spinopelvic sagittal balance and its clinical relevance. 2. Material and Methods Angular and dimensional parameters were measured on 272 lateral radiographies including the pelvis, the femoral heads and the lumbar column, in standardized standing position [7]. For each, a scaling was incorporated allowing correction of the radiographic distortion. Data of four population groups were analyzed (Table 1). Table 1 The first group comprised 61 healthy voluntaries (column A). Data were obtained several years ago from for original orthopaedic studies [5]. At this time, these subjects provided their consent for the use of their radiographic and clinical data. The second group comprised 147 subjects suffering of low back pain from common chronic
Screen-Based Prototyping: A Conceptual Framework  [PDF]
E. Kheirkhah,A. Deraman,Z.S. Tabatabaie
Information Technology Journal , 2009,
Abstract: In any software development process, Requirements Engineering (RE) has been recognized as a critical factor in determining the quality of the software projects. In this study, an efficient technique, that is screen-based prototyping, is proposed to increase users’ involvement in RE tasks and bridge the communication gap between end-users and software developers. This prototyping technique can be employed by most of requirements engineering methodologies. Screen-based prototyping employs the use-case driven approach in constructing prototypes and realize each use-case using a sequence of screens. Graph structure and related concepts are used to implement the prototypes and create various scenarios of use-cases.
The scope of application of incremental rapid prototyping methods in foundry engineering  [PDF]
M. Stankiewicz,G. Budzik,M. Patrza?ek,M. Wieczorowski
Archives of Foundry Engineering , 2010,
Abstract: The article presents the scope of application of selected incremental Rapid Prototyping methods in the process of manufacturing casting models, casting moulds and casts. The Rapid Prototyping methods (SL, SLA, FDM, 3DP, JS) are predominantly used for the production of models and model sets for casting moulds. The Rapid Tooling methods, such as: ZCast-3DP, ProMetalRCT and VoxelJet, enable the fabrication of casting moulds in the incremental process. The application of the RP methods in cast production makes it possible to speed up the prototype preparation process. This is particularly vital to elements of complex shapes. The time required for the manufacture of the model, the mould and the cast proper may vary from a few to several dozen hours.
How to Track Online SLA  [PDF]
Anuradha Rana,Pratima Sharma
Computer Science , 2014,
Abstract: SLA (Service level agreement) is defined by an organization to fulfil its client requirements, the time within which the deliverables should be turned over to the clients. Tracking of SLA can be done manually by checking the status, priority of any particular task. Manual SLA tracking takes time as one has to go over each and every task that needs to be completed. For instance, you ordered a product from a website and you are not happy with the quality of the product and want to replace the same on urgent basis, You send mail to the customer support department, the query/complaint will be submitted in a queue and will be processed basis of its priority and urgency (The SLA for responding back to customers concern are listed in the policy). This online SLA tracking system will ensure that no queries/complaints are missed and are processed in an organized manner as per their priority and the date by when it should be handled. The portal will provide the status of the complaints for that particular day and the ones which have been pending since last week. The information can be refreshed as per the client need (within what time frame the complaint should be addressed).
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