review of indian standards

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THE INSTITUTE FOR ENHANCEMENT OF TECHNOLOGY

A COURSE ON GEOMETRICAL DIMENSIONING AND TOLERANCING

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REVIEW OF INDIAN STANDARS

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REVIEW OF INDIAN STANDARDS RELATED TO DRAWING PRCTICE / DESIGN

IS 696-1972 ‘Code of practice for general engineering drawing‘ was issued indicating the various general recommendations like sheet sizes, scales, dimensioning &

tolerancing, method of projection, surface roughness, welding symbols etc.

ISO has published number of standards on various subjects covered in IS:696-1972.

BIS has subsequently adopted all these standards and IS:696-1972 was made obsolete.

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REVIEW OF INDIAN STANDARDS..Contd.

IS:9609 – English lettering for technical drawings. IS:10711 – Sizes of drawing sheets. IS:10712 – Presentation of item references on technical drawings. IS:10713 – Scales for use in technical drawings. IS:10714 – General principles of presentation on technical drawings. IS:10715 – Presentation of threaded parts on technical drawings. IS:10716 – Rules for representation of springs on technical drawings. IS:10717 – Conventional representation of gears on technical

drawings. IS:10718 – Method of dimensioning and tolerancing cones on technical

drawings. IS:10719 – Method of indicating surface texture on technical

drawings. IS 10720 – Technical drawings for structural metal works. IS:11663 – Conventional representation of common features and

materials on technical drawings. IS:11669 – General principles of dimensioning on technical drawings.

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IS:919 (2 parts) – ISO system of limits and fits.IS:2102(2 parts) – General tolerances.IS:2709 – Guide for selection of fits.IS:8000(4 parts) – Tolerances of form and

position for engineering drawings.

IS:3073 – Assessment of surface roughness.

IS:4218 (6 parts) – ISO Metric screw threads

REVIEW OF INDIAN STANDARDS..Contd.

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RECOMMENDED SCALES

Full Scale Reduced Scale Enlarged Scale 1:1 1:2 10:1

1:2.5 5:1 1:5 2:1 1:10 1:20 1:50 1:100 1:200

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The symbol is indicated on the drawing clearly in the title block.

Symbol for first angle projection

Symbol for third angle projection

Projections

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Dimensions shall be given from visible out lines rather than from hidden lines.

Dimensioning on Engg. Drgs.

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Dimensioning on Engg. Drgs.

It is preferable to give dimensions from a base line or a centre line of a hole or a cylindrical part.

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Dimensioning to a center line shall be avoided except when the center line passes through the centre of a hole or a cylindrical part.

Dimensioning .... Contd..

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Dimension lines and projection lines are drawn as continuous thin lines.

Projection lines should extend slightly beyond the dimension line.


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Construction and intersecting projection lines should extend slightly beyond the point of intersection.

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Leaders which touch the lines shall not be normally inclined less than 30o angle.

Should not be parallel to the adjacent dimension or projection line.


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Use of common leader should be avoided.

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Dimensioning Arrows

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Inscription of dimensions

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The diameter symbol ‘’ is used, before a dimension to indicate the diameter.

Addition of letters and symbols

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The letter ‘R’ is used, before a dimension to indicate a radius.

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The letter ‘SQ’ is used, before a dimension to indicate a square.

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The letter ‘HEX’ is used, to indicate a hexagon before across dimension.

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The word ‘SPHERE’ is used, to indicate a spherical surface before the radius or diameter dimension.

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Special indications

To indicate a surface or a surface zone to give an additional treatment which shall be applied within limits to be specified on the drawing.

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Arrangement of dimensions

Chain dimensioning

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Parallel dimensioning

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Combined dimensioning

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Dimensioning by coordinates

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Dimensioning by coordinates…contd.

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Superimposed running dimensioning

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Equidistant features

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Equal dimensions

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Assembled parts

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The tolerance value restricted to the specified length.

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ANGULAR DIMENSIONS

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DIMENSIONING OF KEY WAYS & TAPERS

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TOLERANCES FOR LINEAR AND ANGULAR DIMENSIONS WITHOUT INDIVIDUAL TOLERANCE INDICATIONS

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INDICATIONS ON THE DRAWINGS

GENERAL TOLERANCES FOR LINEAR DIMENSIONS ARE AS FOLLOWS.

Designation Description

f fine

m medium

c course

v very course

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INDICATIONS ON THE DRAWINGS

General tolerances about the untoleranced dimensions to be given near the title block in the drawing.Ex: Un toleranced dimensions as per : IS – 2102 – medium. Permissible deviations for linear dimensions

Permissible deviations for basic size rangeDesignati

onDescriptio

n

0.5 – 3 3 – 6 6 - 30 30 – 120

120 -400

400 -1000

1000 -2000

2000 -4000

f fine ± 0.05

±0.05

±0.1 ±0.15 ±0.2 ±0.3 ±0.5 -

m mediu

m

± 0.1 ±0.1 ±0.2 ±0.3 ±0.5 ±0.8 ±1.2 ±2

c course ± 0.2 ±0.3 ±0.5 ±0.8 ±1.2 ±2 ±3 ±4

v very course

- ±0.5 ±1 ±1.5 ±2.5 ±4 ±6 ±8For nominal sizes below 0.5mm, the deviations shall be indicated adjacent to the relevant nominal size (s)

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GENERAL TOLERANCES FOR RADII AND CHAMFER HEIGHTS

Permissible deviations for basic size range

Designation

Description

0.5 - 3 Over 3 – 6 Over 6

f fine

± 0.2 ± 0.5 ± 1m medium

c course

± 0.4 ± 1 ± 2v very course

For nominal sizes below 0.5mm, the deviations shall be indicated adjacent to the relevant nominal size (s)

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ANGULAR DIMENSIONS

Permissible deviations for ranges of lengths, in mm, of the shorter side of the angle concerned

Designation

Description

Upto 10 Over 10-50

Over 50-120

Over 120-400

Over 400

f fine

±1o ±0o30’

±0o20’ ±0o10’

±0o5’m medium

c course ±1o30’

±1o ±0o30’ ±0o15’

±0o10’

v very course ±3o ±2o ±1o ±0o30’

±0o20’

Shorter side of the angle concerned

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TOLERANCE DISPOSITION CHART

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Accuracy expected of manufacturing process

review of indian standards

Documents

technical drawings

symbolsthe institute

dimensionsthe institute

enhancement of technologyis

method of dimensioning

hidden lines

intersecting projection

parts general