scholarly journals Tri-Planar Geometric Dimensioning and Tolerancing Characteristics of SS 316L Laser Powder Bed Fusion Process Test Artifacts and Effect of Base Plate Removal

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3575
Author(s):  
Baltej Singh Rupal ◽  
Tegbir Singh ◽  
Tonya Wolfe ◽  
Marc Secanell ◽  
Ahmed Jawad Qureshi
Keyword(s):  
Base Plate ◽  
Process Variations ◽  
Quantitative Information ◽  
Experimental Result ◽  
Research Gaps ◽  
Plate Removal ◽  
Geometric Tolerance ◽  
Geometric Dimensioning And Tolerancing ◽  
Geometric Tolerances ◽  
Significant Research

The precision of LPBF manufactured parts is quantified by characterizing the geometric tolerances based on the ISO 1101 standard. However, there are research gaps in the characterization of geometric tolerance of LPBF parts. A literature survey reveals three significant research gaps: (1) systematic design of benchmarks for geometric tolerance characterization with minimum experimentation; (2) holistic geometric tolerance characterization in different orientations and with varying feature sizes; and (3) a comparison of results, with and without the base plate. This research article focuses on addressing these issues by systematically designing a benchmark that can characterize geometric tolerances in three principal planar directions. The designed benchmark was simulated using the finite element method, manufactured using a commercial LPBF process using stainless steel (SS 316L) powder, and the geometric tolerances were characterized. The effect of base plate removal on the geometric tolerances was quantified. Simulation and experimental results were compared to understand tolerance variations using process variations such as base plate removal, orientation, and size. The tolerance zone variations not only validate the need for systematically designed benchmarks, but also for tri-planar characterization. Simulation and experimental result comparisons provide quantitative information about the applicability of numerical simulation for geometric tolerance prediction for the LPBF process.

scholarly journals Automated Process Planning System for End Milling Operation Constrained by Geometric Dimensioning and Tolerancing (GD&T)

2019 ◽  
Vol 13 (6) ◽  
pp. 825-833
Author(s):  
Isamu Nishida ◽  
◽  
Shogo Adachi ◽  
Keiichi Shirase
Keyword(s):  
Process Planning ◽  
Planning System ◽  
Cad Model ◽  
Geometric Tolerance ◽  
3D Cad ◽  
Geometric Dimensioning And Tolerancing ◽  
Geometric Tolerances ◽  
Automated Process Planning ◽  
Process Planning System ◽  
Automated Process

To realize autonomous machining, it is necessary to focus on machining tools and also on the automation of process planning in the preparation stage. This study proposes a process planning system that automatically defines the machining region and determines the machining sequence. Although previous studies have explored computer-aided process planning, only a few have considered geometric tolerances. Geometric tolerances are indicated on product drawings to eliminate their ambiguity and manage machining quality. Geometric dimensioning and tolerancing (GD&T) is a geometric tolerance standard applied to a three-dimensional computer-aided design (3D CAD) model and are expected to be used for the digitization of manufacturing. Therefore, this study developed an automated process planning system by using GD&T as a sequencing constraint. In the proposed system, the machining sequence is automatically determined by the geometrical constraints, which indicate whether the tool can approach, and GD&T, which indicates the geometric tolerance and datum in a 3D CAD model. A case study validated the proposed method of automated process planning constrained by GD&T. The result shows that the proposed system can automatically determine the machining sequence according to the geometric tolerance in a 3D CAD model.

Representation and reasoning of geometric tolerances in design

1997 ◽  
Vol 11 (4) ◽  
pp. 325-341 ◽  
Author(s):  
Jhy-Cherng Tsai ◽  
Mark R. Cutkosky
Keyword(s):  
Quality Control ◽  
Recent Work ◽  
Functional Requirements ◽  
Geometric Tolerance ◽  
Geometric Dimensioning And Tolerancing ◽  
Design Specifications ◽  
Geometric Tolerances ◽  
Dimensioning And Tolerancing ◽  
Different Types ◽  
Representation Scheme

AbstractThe geometric dimensioning and tolerancing (GD&T) specifications of a design are directly associated with its performance and functional requirements. They also govern the manufacturing and quality control processes needed to achieve those requirements. This paper reviews recent work in geometric tolerance representation and reasoning and presents a generic and uniform graph-based representation scheme, called the Tolerance Network, to represent GD&T specifications across a part or assembly. The network can accommodate GD&T specifications related to the function, behavior, manufacturing, and inspection requirements embedded in design specifications and supports the use of different types of tolerances. The network also accommodates common design practices such as the specification of overconstrained features and parts. The necessary properties of such a network are discussed that allow under- and overconstrained design specifications to be detected and analyzed.

scholarly journals The Influence of Automated Machining Strategy on Geometric Deviations of Machined Surfaces

2021 ◽  
Vol 11 (5) ◽  
pp. 2353
Author(s):  
Ján Varga ◽  
Teodor Tóth ◽  
Peter Frankovský ◽  
Ľudmila Dulebová ◽  
Emil Spišák ◽  
...  
Keyword(s):  
Control System ◽  
Surface Quality ◽  
Coordinate Measuring Machine ◽  
Geometric Tolerance ◽  
Geometric Tolerances ◽  
Significant Difference ◽  
Geometric Deviations ◽  
Measuring Machine ◽  
Overlap Parameter ◽  
Total Average

This paper deals with various automated milling strategies and their influence on the accuracy of produced parts. Among the most important factors for surface quality is the automated milling strategy. Milling strategies were generated from two different programs, CAM system SolidCAM, with the help of workshop programming in the control system Heidenhain TNC 426. In the first step, simulations of different toolpaths were conducted. Using geometric tolerance is becoming increasingly important in robotized production, but its proper application requires a deeper understanding. This article presents the measurement of selected planes of robotized production to evaluate their flatness, parallelism and perpendicularity deviations after milling on the coordinate measuring machine Carl Zeiss Contura G2. Total average deviations, including all geometric tolerances, were 0.020 mm for SolidCAM and 0.016 mm for Heidenhain TNC 426. The result is significantly affected by the flatness of measured planes, where the overlap parameter of the tools has a significant impact on the flatness of the surface. With interchangeable cutter plate tools, it is better to use higher overlap to achieve better flatness. There is a significant difference in production time, with SolidCAM 25 min and 30 s, and Heidenhain 48 min and 19 s. In accordance with these findings, the SolidCAM system is more suitable for production.

Study on Geometric Tolerances Information in Integrated Manufacturing Processes

2010 ◽  
Vol 37-38 ◽  
pp. 1292-1295
Author(s):  
Yan Chao ◽  
Hai Feng Zhang ◽  
Li Qun Wu
Keyword(s):  
Life Cycle ◽  
Data Model ◽  
Manufacturing Process ◽  
Product Life Cycle ◽  
Critical Role ◽  
Manufacturing Processes ◽  
Product Life ◽  
Internet Technologies ◽  
Geometric Tolerance ◽  
Geometric Tolerances

Tolerance information plays a critical role in many steps of the product life cycle. It is especially important due to the advances in Internet technologies and increasing integration requirements from industry. In this paper, geometric tolerances information in manufacturing process (IMP) is studied, and the layered conformance level of geometric tolerances is established according to ASME Y14.5-1994, STEP and DMIS. An EXPRESS-G data model of geometric tolerance information in IMP is established. The XML language is used to represent and program the geometric tolerances information in IMP.

Formation of Geometric Tolerance Zones for Polyhedral Objects

1997 ◽  
Author(s):  
Utpal Roy ◽  
Bing Li
Keyword(s):  
Variational Model ◽  
Tolerance Zone ◽  
Geometric Tolerance ◽  
Geometric Tolerances ◽  
Polyhedral Objects ◽  
Different Types ◽  
Tolerance Zones ◽  
Algebraic Constraints ◽  
Size Tolerance ◽  
Part Model

Abstract This paper presents a scheme for establishing geometric tolerance zones for polyhedral objects in solid modelers. The proposed scheme is based on a surface-based variational model. Variations are applied to a part model by varying each surface’s model variables. Those model variables are constrained by some algebraic relations derived from the specified geometric tolerances. For size tolerance, two types of tolerance zones are considered in order to reflect two different types of size tolerances. For any other geometric tolerance (form, orientation or positional), the resultant tolerance zone is defined by the combination of size tolerance and that particular geometric tolerance specifications. Appropriate algebraic constraints (on the model variables) are finally used to establish the tolerance zone boundaries in the surface-based variational model.

scholarly journals Complementary Measurements of Residual Stresses Before and After Base Plate Removal in an Intricate Additively-Manufactured Stainless-Steel Valve Housing

2020 ◽  
Vol 36 ◽  
pp. 101555
Author(s):  
Bjørn Clausen ◽  
Christopher R. D’Elia ◽  
Michael B. Prime ◽  
Michael R. Hill ◽  
Joseph E. Bishop ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Residual Stresses ◽  
Base Plate ◽  
Plate Removal ◽  
Before And After ◽  
Valve Housing

On the Inflow Phenomenon in Near Field of Buoyant Jet at Low Froude Number

2012 ◽  
Author(s):  
Atsushi Maeda ◽  
Takayuki Yamagata ◽  
Nobuyuki Fujisawa
Keyword(s):  
Reynolds Number ◽  
Froude Number ◽  
Near Field ◽  
Quantitative Information ◽  
Experimental Result ◽  
Inflow Rate ◽  
Buoyant Jet ◽  
Square Duct ◽  
Wide Range ◽  
Low Froude Number

In the present paper, the inflow phenomenon in the near-field of a buoyant jet issuing from a square duct is studied by using scanning LIF and scanning PIV measurements. The scanning LIF visualization allows an insight into the critical condition of the inflow phenomenon in a wide range of Froude number and Reynolds number. While, the scanning PIV allows the quantitative information on the inflow rate through the duct exit. The experimental result shows that the critical Froude number increases with an increase in Reynolds number in the duct exit up to Reynolds number 2,000, though it is weakened at higher Reynolds number. The examination of the inflow rate indicates that the large magnitude of the inflow rate occurs in the lower Froude number and Reynolds number.

Analysis of the Influence of Fixture Locator Errors on the Compliance of Work Part Features to Geometric Tolerance Specifications

2003 ◽  
Vol 125 (3) ◽  
pp. 609-616 ◽  
Author(s):  
Rodrigo A. Marin ◽  
Placid M. Ferreira
Keyword(s):  
Inverse Problem ◽  
Reference Frame ◽  
Forward Problem ◽  
Acceptable Level ◽  
Geometric Tolerance ◽  
Mechanical Part ◽  
Geometric Tolerances ◽  
Nc Program ◽  
Functional Features ◽  
Position And Orientation

A machining fixture controls position and orientation of datum references (used to define important functional features of the geometry of a mechanical part) relative the reference frame for an NC program. Inaccuracies in fixture’s location scheme result in a deviation of the work part from its nominal specified geometry. For a part to be acceptable this deviation must be within the limits allowed by the geometric tolerances specified. This paper addresses the problem of characterizing the acceptable level of inaccuracy in the location scheme so that the features machined on the part comply with the limits associated with its geometric tolerances. First we solve the “forward problem” that involves predicting the tolerance deviation resulting at a feature from a known set of errors on the locators. However, the paper concentrates on solving the “inverse” problem that involves establishing bounds on the errors of the locators to ensure that the limits specified by geometric tolerances at a feature are not violated.

Three-Dimensional Verification of Geometric Tolerances With the “Fitting Gauge” Model

2006 ◽  
Vol 7 (1) ◽  
pp. 26-30 ◽  
Author(s):  
Eric Pairel
Keyword(s):  
Conceptual Model ◽  
Three Dimensional ◽  
Gauge Model ◽  
Geometric Tolerance ◽  
Geometric Tolerances ◽  
Experimental Software

Thanks to the “fitting gauge” conceptual model, developed in our lab, any geometric tolerance can be interpreted in the form of a virtual three-dimensional gauge, which is able to be assembled with the part to be inspected. From a file containing the sampled points of the part to inspect, the experimental software, using this conceptual model, permits one to build the virtual gauge defined by the geometric tolerance and to check that it can be assembled and adjusted, according to a precise order, with clouds of points representing the part. Checking the geometric tolerances is thus strictly in conformity with their standardized meaning and it is extremely simplified.

scholarly journals Roma Population in the Spanish Education System: Identifying Explanatory Frameworks and Research Gaps

2021 ◽  
pp. 201-227
Author(s):  
Francisco Javier Ullán de la Rosa ◽  
Hugo García Andreu
Keyword(s):  
Academic Success ◽  
Literature Review ◽  
Compulsory Education ◽  
Research Gaps ◽  
Theoretical Frameworks ◽  
Roma Population ◽  
Educational Situation ◽  
Significant Research ◽  
Education Gap ◽  
The University

AbstractThis chapter makes a literature review based on the Grant and Booth qualitative systematic methodology of the studies about the educational situation of the Roma in Spain, with an wider, extended scope that allows to compare the findings with those conducted on other countries’ Roma populations. Studies on the Roma educational situation in Spain are hindered by the lack of official, periodical statistics, having to rely on sample-based surveys and ethnographic studies. In spite of the inaccuracy of the studies all of them show, as a general picture, a staggering educational gap between the Roma and the rest of society which is common to all Western countries. Most of the studies on Roma education have concentrated in this negative aspect. Numerous theoretical frameworks have been developed to explain this staggering education gap. All them acknowledge the phenomenon as a multidimensional one but for heuristic purposes they can be ordered along an endogenous/exogenous factors continuum depending on how much they stress the weight of factors stemming from characteristics of the Roma ethnic group itself or, on the contrary, of the majority non-Roma society. The literature review has also identified an emergent critical current that sees this studies focused on educational underachievement as a sharing a common essentialist bias that helps to reinforce the stigmatization of Roma and have turned to focus, instead, on the study of academic success among the Roma. Although this emerging field is very promising, our review has identify several significant research gaps in this regard: a lack of longitudinal studies, a lack of studies on the Roma upper and middle classes and a lack of studies on Roma students in post-compulsory education, particularly the university level. This article encourages researchers to fill this gaps with the conviction that the knowledge obtained can help combat the negative stereotypes and the self-fulfilling prophecy effect that approaches focused on Roma underachievement may have.

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