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Geometric Tolerancing

Geometric tolerancingAgreed by ISO 1001 included in BS308

(drawing standard)

Author: Leicester College

Date created:

Date revised: 2009

Abstract:

Geometric tolerancing is a method which is widely used in industry when the more basic systems of tolerancing component features does not

provide the required accuracy.

The system of geometric tolerancing id detailed together with the particular features of the system.

Leicester College 2009. This work is licensed under

a Creative Commons Attribution 2.0 License.
http://creativecommons.org/licenses/by/2.0/uk/http://creativecommons.org/licenses/by/2.0/uk/http://creativecommons.org/licenses/by/2.0/uk/


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These files support the Edexcel HN unit

Design for Manufacture (NQF L4)

File Name Unit Outcome Key Words

Design for assembly 1.1, 1.2,1.4 Overview, Cost, quality, reliability, assembly, guidelines

FMS 2.2

Models, work cycles, volume, machine utilisation, automation,flexible, systems

Geometric

Tolerancing

3.1,3.2 Geometric, tolerance, system, symbols, orientation, BS, ISO,location, runout, datum

Industrial Robots 2.2,2.3 Robot, industrial, robot arm, Cartesian, polar, cylindrical, jointedarm

Jigs and Fixtures 2.1,2.3 Efficiency, production, jigs, fixtures, tooling, production,Kinematics 2.1,2.3 Machines, kinematics, Degrees of freedom, configuration,

space, work space, robot, joints, forward, inverse

For further information regarding unit outcomes go to Edexcel.org.uk/ HN/ Engineering /

Specifications



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Purpose Geometric tolerance symbols give precise

indication of GEOMETRIC requirement for agiven feature / drawing

Symbols universally understood

Used when normal dimensioning andtolerancing are not sufficient for

requirements of component / operation


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Only use geometric tolerancing if it isabsolutely necessary to the required design

function

It adds to the cost of both manufacture andinspection


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The symbols used represent a range ofpotential geometric features of a form offeatureFour types

Form

Orientation

Location

Runout


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Symbol constructionDescriptionToleranced featureindications

direct

By letter

Datum indications DirectBy letter

Datum targets

Theoretically exact

dimensionProjected tolerancezone

Max. Metal condition


7/9Geometric Tolerancing

Tolerance frame

This type of frame used when no datum isrequired

This type of frame used when a datum is specified mandatory for some geometric features

Feature symbol Tolerance

Feature symbol tolerance datum



DATUMSA datum may be a plane surface or axis.

For practical purposes the plane surface oraxis is used for manufacture or inspection

If the toleranced feature is related to adatum, this is shown by a datum letterwhich is indicated in the tolerance frameby a capital letter



This resource was created Leicester College and released as an open educational resource through the OpenEngineering Resources project of the Higher Education Academy Engineering Subject Centre. The OpenEngineering Resources project was funded by HEFCE and part of the JISC/HE Academy UKOER programme.

2009 Leicester College

This work is licensed under a Creative Commons Attribution 2.0 License.

The JISC logo is licensed under the terms of the Creative Commons Attribution-Non-Commercial-No Derivative Works 2.0 UK: England& Wales Licence. All reproductions must comply with the terms of that licence.

The HEA logo is owned by the Higher Education Academy Limited may be freely distributed and copied for educational purposes only,provided that appropriate acknowledgement is given to the Higher Education Academy as the copyright holder and original publisher.

The Leicester College name and logo is owned by the College and should not be produced without the express permission of theCollege.
http://www.jisc.ac.uk/http://engsc.ac.uk/http://engsc.ac.uk/an/oer-project/oer-project.asphttp://creativecommons.org/licenses/by/2.0/uk/

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