Definition Flatness Error
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marked with Prussian blue and the other surface rubbed over it. The distribution of colour over the other surface gives a rough idea of high and low points on the surface. This method is usually suitable for definition of flatness tolerance small plates and not for large surfaces. Mathematically, flatness error of a surface states definition of flatness in metrology that the departure from flatness is the minimum separation of a pair of parallel planes which will just contain all points
Define Flatness
on the surface. The deviation of a large surface such as surface table or machine table from the true plane may be determined by the use of either a spirit level or an auto-collimator. The
Define Flatness Problem
principle of the method is same, whether the apparatus used is auto-collimator or spirit level. According to IS : 2063—1962, a surface is deemed to be flat within a given range of measurement when the variation of the perpendicular distance of its points from a geometrical plane (this plane should be exterior to the surface to be tested) parallel to the general trajectory of the plane to be tested remains flatness meaning below a given value. The geometrical plane may be represented either by means of a surface plane or a family of straight lines obtained by the displacement of a straight edge or a spirit level or a light beam : Flatness deviations (errors of flatness) are indicated as follows : (i) … µor mm per metre when convexities are allowed as well as concavities ; (ii) concave to … |x or mm, when, between the ends, only concave surfaces are allowed ; and (iii) convex to … \x. or mm, when, between the ends, only convex surfaces are allowed. It is well known that a surface can be considered to be composed of an infinitely large number of lines. The surface will be truly flat only if all the lines are straight and they lie in the same plane. Let us study the case of rectangular table. From Fig. 7.4, it is obvious that all the generators (lines) are straight and parallel to the sides of the rectangle in both the perpendicular directions. Even then it is not truly flat, but concave and convex along two diagonals. Thus for the verification of a surface to be truly flat, it is essential to measure the straightness of diagonals in additio
help to improve this article by introducing more precise citations. (April 2009) (Learn how and when to remove this template message) In manufacturing and mechanical engineering, flatness is an important geometric condition for workpieces and tools.
Flatness Checking Method
In the manufacture of precision parts and assemblies, especially where parts will be required flatness definition mechanical engineering to be connected across a surface area in an air-tight or liquid-tight manner, flatness is a critical quality of the manufactured surface flatness definition surfaces. Such surfaces are usually machined or ground to achieve the required degree of flatness. High-definition metrology, such as digital holographic interferometry, of such a surface to confirm and ensure that the required degree of http://what-when-how.com/metrology/flatness-testing-metrology/ flatness has been achieved is a key step in such manufacturing processes. Flatness may be defined in terms of least squares fit to a plane ("statistical flatness"), worst-case or overall flatness (the distance between the two closest parallel planes within). Two parts that are flat to about 1helium light band (HLB) can be "wrung" together, which means they will cling to each other when placed in contact. This phenomenon https://en.wikipedia.org/wiki/Flatness_(manufacturing) is commonly used with gage blocks. Geometric dimensioning and tolerancing has provided geometrically defined, quantitative ways of defining flatness operationally. History[edit] Joseph Whitworth popularized the first practical method of making accurate flat surfaces during the 1830s, using engineer's blue and scraping techniques on three trial surfaces. By testing all three in pairs against each other, it is ensured that the surfaces become flat. Using two surfaces would result in a concave surface and a convex surface. Eventually a point is reached when many points of contact are visible within each square inch, at which time the three surfaces are uniformly flat to a very close tolerance.[1] Up until his introduction of the scraping technique, the same three plate method was employed using polishing techniques, giving less accurate results. This led to an explosion of development of precision instruments using these flat surface generation techniques as a basis for further construction of precise shapes. References[edit] Wayne R. Moore, Foundations of Mechanical Accuracy, Moore Special Tool Company, Bridgeport, CT (1970) Whitworth, J. 1858, Plane Metallic Surfaces, Longman, Brown, and Co., London & Manchester. External links[edit] Flatness Overview - GD&T Basics Two surface plates made by Whitworth What is the right Flatness Tolerance for a Gasket Application Retrieved from "https://en.wikipedia.org/w/index.php?title=Flatness_(ma
institution loginHelpJournalsBooksRegisterJournalsBooksRegisterSign inHelpcloseSign in using your ScienceDirect credentialsUsernamePasswordRemember meForgotten username or password?Sign in via your institutionOpenAthens loginOther institution login Download full text in PDF Article Article + other articles in this issue Loading... Export http://www.sciencedirect.com/science/article/pii/S2212827113005908 You have selected 1 citation for export. Help Direct export Save to Mendeley Save to RefWorks Export file Format RIS (for EndNote, ReferenceManager, ProCite) BibTeX Text Content Citation Only Citation and Abstract Export Advanced search Close This document does not have an outline. JavaScript is disabled on your browser. Please enable JavaScript to use all the features on this page. definition of Procedia CIRP Volume 10, 2013, Pages 271-275 The Twelfth CIRP Conference on Computer Aided Tolerancing
Open Access The Assessment of Straightness and Flatness Errors Using Particle Swarm Optimization ☆ Author links open the overlay panel. Numbers correspond to the affiliation list which can be exposed by using the show more link. Opens overlay C. Cui a, b, ⁎, cuichc@hqu.edu.cn, Opens overlay definition of flatness T. Li a, Opens overlay L.A. Blunt a, Opens overlay X. Jiang a, Opens overlay H. Huang b, Opens overlay R. Ye b, Opens overlay W. Fan b aEPSRC Innovative Manufacure Research Centre in Advanced Metrology, Centre for Precision Technologies, School of Computing and Engineering, University of Huddersfield, Queensgate, Huddersfield, HD1 3DH, UKbCollege of Mechanical Engineering and Automation, Huaqiao University, Xiamen, 361021, China Available online 19 September 2013 Show more doi:10.1016/j.procir.2013.08.041 Get rights and content Under a Creative Commons license AbstractThe straightness and flatness errors are generally assessed by using the Least Squares Method (LSM). However, the results obtained from LSM often overestimate the tolerances, and are not consistent with the ISO standards’ definitions. To this end, this paper presents a method to evaluate those errors by using particle swarm optimization (PSO). The realization technique is detailed. The experimental data is utilized to verify this algorithm, together with a comparison with some typical optimization algorithms. Keywords form error; straightness; flatness; assessment; Particle Swarm Optimization(PSO); optimization Download full text in PDF References [1] ISO 1101(2004), Geometrical Product Specification (GPS) - Geometrical tolerancing-