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ENGINEERING STANDARDS

ByPalaniyappan K.

Bangalore.


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INTRODUCTION

The idea of the designer (product) must beconveyed to the production engineer so asto enable him to manufacture it.

The shop floor engineer can be made tounderstand easily the shape, size and

production processes required tomanufacture the product only throughsketches.

The sketches, when drawn accuratelyaccording to the standards to convey all thenecessary information to enable it formanufacturing and assembly, are called

manufacturing drawing.


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Standards

As Manufacturing Drawings are used to

communicate technical information bothwithin and outside a country, for theunmistakable exchange of technicalinformation both at the national and

international levels, it becomes essentialto have a uniform drafting practice.

The standards and conventions used in

drawings are discussed in the followingslides.


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DRAWING SHEETS

The drawing sheets are standardizedand designated as

A0, A1, A2, A3 & A4


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DRAWING SHEETS

Two successive

format of a seriesof sizes areobtained by halvingalong the length ordoubling along thewidth. The areas ofthe two sizes are in

the ratio 1:2 asshown in the figure


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DRAWING SHEET LAYOUT


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TITLE BLOCK

All drawing sheets must have a title

block.The format of the title block must be

standardized.

The title block must contain the name &logo of the organization

The title block can have technical

information like unspecified tolerance,surface roughness values etc.


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TITLE BLOCK The following details are to be

mentioned in a title block:

1. Designation of the item

2. Drawing number / Group number

3. Project number / Machine number

4. Drawing scale & projection

5. Sheet number & number of sheets

6. Material

7. Drawn / Checked / Approved status

8. Revision status

9. Technical Details


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TITLE BLOCK


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DRAWING SCALE

All drawings must be drawn to scale.

The preferred scales for drawing are


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DRAWING SCALE

If any dimension is not as per scale, the

dimension text must be underlined.If a dimension is missing, or in case of

any doubt, the drawing should never be

measured.As far as possible the drawing scale for

component drawings must be 1:1


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DRAWING DETAILS

The following details are to be

mentioned in an assembly drawing. Complete sketch of the assembly with

adequate sections and views. All the partsof the assembly must be shown.

Section cutting plane lines, direction ofview & section/view names.

Overall dimensional details and other

important dimensions Two extreme positions of parts which are

moving.


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DRAWING DETAILS

Partial details of adjacent sub assemblies

Details of bought out items withspecification

Item numbers for the parts.

Bill of materials indicating part number,

designation, quantity etc.

Other necessary instructions if required inthe form of notes.


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DRAWING DETAILS

The following details are to be

mentioned in a component drawing. Complete sketch of the part with adequate

sections and views should be shown.

Section cutting plane lines, direction ofview & section/view names should bespecified.

Complete dimensional details should be

provided with tolerance wherever required. Reference surface & geometrical accuracy

details should be provided whereverrequired


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DRAWING DETAILS

Surface finish and General surface finishrequirements should be mentioned.

Heat treatment details if necessary shouldbe given in the drawing.

Other necessary instructions if required in

the form of notes can be provided in thedrawing.


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Bill of Materials

When the design of a mechanism orassembly/ subassembly of a machine hasbeen completed, a bill of materials or a partlist is made.

This list must show the drawing number,

part name, material used, blank size,standard number and quantity required inthe assembly/ subassembly.

The bill of materials must also show a list

of all standard parts, quantity required andremarks if any.


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PART LIST / BILL OF MATERIALSl No. Name Dwg No. Material Qty Size Std No. Remarks

Project No. Prepared ByProject Name Approved By LOGOAssy/ Sub-assyNo. Date

Revision

LOGO


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NUMBER REGISTERAssy / Part Dwg No. Name Used in Assy

Project No. Prepared ByProject Name Approved By LOGO

DateRevision

LOGO


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LINE TYPES


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TYPES OF LINES

A. Continuous thick: Visible outlines

(outlines to be bold & dark)B. Continuous thin: Dimension lines,

leader lines, extension lines,

construction lines, outlines of adjacentparts & hatch lines.

C. Continuous thin wavy: Irregularboundary lines, short break lines.

D. Short dashes medium: Hiddenoutline & edges.


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TYPES OF LINES

E. Long chain thin: Center lines, pitch

circles, extreme positions of movableparts.

F. Long chain thick at ends & thin

elsewhere: Cutting plane linesG. Long chain thick: To indicate

surfaces which are to receive additionaltreatment.

H. Short zigzag thin : Long break lines.


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TYPES OF LINES (Application)


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Recommended Sizes forLetters & Numerals

DRAWING CONVENSIONS


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DRAWING CONVENSIONS

DRAWING CONVENSIONS


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DRAWING CONVENSIONS

DRAWING CONVENSIONS


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DRAWING CONVENSIONS

DRAWING CONVENSIONS


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DRAWING CONVENSIONS

CENTER HOLES


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CENTER HOLES

The dimensions for center holes is asindicated in page 133 of CMTI handbook.

The representation of center holes on adrawing is as indicated in page 134 ofCMTI hand book.

RELIEF GROOVES


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RELIEF GROOVES

The standards & dimensions of reliefgrooves for different application are as

indicated in page 139 of CMTI handbook.

DIMENSIONING


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DIMENSIONING

Dimension is a numerical value

expressed in appropriate units ofmeasurement & indicated graphically ontechnical drawings with lines, symbols &notes, so that the feature is completely

defined.

Individual drawings shall use the sameunit for all dimensions without showing

the unit symbol.

Each feature shall be dimensioned onlyonce in a drawing.

DIMENSIONING


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DIMENSIONING

Different ways of dimensioning:

Linear dimensioning Angular dimensioning

Aligned dimensioning

Ordinate dimensioning Co-ordinate dimensioning

Radius/Diameter

Leader

DIMENSIONING


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DIMENSIONING

Classification of dimensions:

Functional: A dimension that is essentialto the function of the component.

Non-functional: A dimension that is not

essential to the function of thecomponent.

Auxiliary: A dimension given for

information only. It does not governproduction or inspection. An auxiliarydimension is enclosed in brackets & notolerance applies to it.

DIMENSIONING


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DIMENSIONING

DIMENSIONING


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DIMENSIONING

DIMENSIONING


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DIMENSIONING

DIMENSIONING


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DIMENSIONING


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Thank

You

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