Basics Of Engineering Dwg Standards

Basics of Engineering Drawing

What is Engineering Drawing? “Engineer’s Language” It is engineering language used to communicate within the engineering community to express their thoughts (designs) & get the product produced. Why drawings are required? To create common communication platform across the whole engineering community. Also one picture is better than 1000 words, isn’t it?

Part Drawings: Detail drawings completely describe a single part with multiview orthographic projections. • Should provide all the information necessary to economically manufacture a high quality part. •

Assembly Drawings: • Assembly drawings are used to show the position and functional relationship of parts in an assembly, also via multiview orthographic projections. • Generally they have no dimensions on them. • Parts are 'balloon' identified and referenced to either detail drawing numbers or catalog numbers, via a Bill of Materials (BOM)

Drawing sheet sizes

• An A0 sheet has an area of 1m2 • The sides are in the proportion 1: √2

Drawing Border (or margin) • The drawing should have a border of about 10 mm • Space should be left for binding and hole-punching, if the drawing is to be placed in a file

Title Block and Notes • Organization • e.g. IES • May include logo

• Title (Job and Drawing) • Job Title (e.g. Portland Building) • Drawing Title (e.g. Ground Floor Plan)

• Drawing Number • A reference which identifies the drawing within the job and organization

• Revision Number • Only used if changes are made to the drawing after it has been initially published • Should increment with each revision (e.g. 1,2,3,… or A,B,C,… ) • Details of each revision should be kept in Revision Table, in Notes area (see later)

• Issue Number • Should be unique to each paper copy of the drawing that is made (may be written in by hand after printing) •

An Issue Book should show details of who the particular drawing was issued to, and when it was issued

• Scale • Express as ratio drawing unit : real world unit

• Scales other than those above should only be used in exceptional circumstances (ensure that • sensible numbers are used, e.g. 1:2500, not 1:2384) • Check that the scale on the printed drawing is correct – this is very important (measure it) • Different parts of the drawing may be to different scales – state the main scale in the Title Block, and other scales next to the relevant drawing part

• Date •

The date of the original drawing (later revisions will have their own date noted with the details of the revision)

• Drawn By • The name or initials of the (principal) person who created the drawing • For student assignments, this should normally be your Student ID Number (HEMIS Number)

• Approval Signature • The original drawing should be checked and approved by a competent person • Later revisions have their own approval signatures (see Notes and Revisions Table)

• Notes • A separate area, not part of the Title Block (see Location, later) • Include relevant notes, e.g.: • All dimensions in mm • All levels in meters • Do not scale off drawing – if in doubt, ask • May also include a key to symbols used in the drawing • May include a Location Figure (a small drawing which shows the location of the main drawing relative to a larger area) • Should also include a Revisions Table

• Revisions Table • In Notes area • The table may be upside down (with column headings in the bottom row)

• Location Title Block should be in the bottom right-hand corner – for easy searching of required drawing in a collection of drawings • Notes should be vertically above, or horizontally to the left of the Title Block (Notes are not always necessary) •

• Folding a Drawing See extract from British Standard on the Engineering Communications unit web (BS 1192:Part 1:1984) • The BS shows how to fold a drawing to ensure that the Title Block is always visible • The folding method allows drawings to be placed in a ring binder file and opened for viewing without removing the drawing from the file • All paper sizes from A3 to A0 are included •

Title block examples

Line fonts:

100  20

Black = object line and hatching Red = hidden line Blue = center line Magenta = phantom line or cutting plane Green = Dimension Cyan = Leader

Lettering:

Viewer

Angle of projections: First Angle

II

I Object Viewer

III

IV

Viewer

Angle of projections: Second Angle

II

I

Object Viewer

III

IV

Viewer

Angle of projections: Third Angle

II

I

Viewer Object

III

IV

Viewer

Angle of projections: Forth Angle

II

I

Viewer Object

III

IV

TOP

FRONT

RIGHT SIDE

Angle of projections convention:

Third Angle

First Angle

Engineering drawing views A view of an object (actual or imagined) as it would be seen by an observer who looks at the object either in a chosen direction or from a selected point of view. Pictorial sketches often are more readily made and more clearly understood than are front, top, and side views of an object. In making a pictorial drawing, the viewing direction that shows the object and its details to the best advantage is chosen. The resultant drawing is Orthographic. Orthographic Views are two-dimensional views of objects where the viewpoint of the object is at right angles to (or looking directly at) surfaces. They are used in technical and engineering drawings for accuracy. The most commonly used pictorial drawing for technical information is called isometric drawings. Isometric drawings were developed to approximate perspective, but are much easier to draw. For a square box, all the sides are drawn as vertical lines, or at 30 degrees to the horizontal. See Fig.1 In the Isometric pictorial, the direction of its axes and all measurements along these axes are made with one scale (Fig. 1). Oblique pictorial drawings, while not true orthographic views, offer a convenient method for drawing circles and other curves in their true shape (Fig. 2).

Fig. 1

Fig. 2

Orthographic views ORTHOGRAPHIC VIEWS

You can also think of these views as an object inside a box with its surfaces "projecting" on to the sides of the box. You can then unfold the box to project the views on a flat surface. Because the views are only two dimensional, more than one view is needed to completely describe the object. Usually two or three views is enough (Front, Top and Side), but often more are required.

Different types of drawing views HALF VIEWS AND PARTIAL VIEWS : Half Views and Partial views are used to simply save space when half of, or portion of a view is not needed or is redundant. When objects are symmetrical and you are limited in the amount of space on the drawing or in drafting time, you may reduce an object image to only those features needed for minimum representation or a partial view. You may use partial views in conjunction with sectioning.

Different types of drawing views AUXILIARY VIEWS Auxiliary Views are used to accurately depict features on Inclined Surfaces. If there is no feature on the inclined surface, there is no need to create an auxiliary view.

Importance of choosing the Front View Here are the orthographic projections for the 2 boxes. Notice that the one on the right takes up much more space that the one on the left. Notice also that the views are labeled by location, and are not related to the part of the object in the view.

Exploded Views

Views that pictorially represent how objects and assemblies fit together are called exploded views. You may use any pictorial method including isometric projection for exploded views with isometric representation the most Common exploded views appear primarily in design presentations, catalogs, sales literature and assembly instructions.

An exploded view in isometric projection

Sectional views

Section views are used to get rid of the confusing hidden lines. To produce a sectional view, an imaginary plane, called the cutting plane, cuts through the object and the two halves are separated to expose the interior construction. The direction of sight may be toward the right or left half, while you disregard the portion of the object nearest the observer. Use a cutting plane line or viewing plane line to indicate the cutting plane and the direction of sight. Sectional views may be further classified as full, half, broken-out, revolved, removed, offset, aligned sections, and partial views.

Full and Half sections. FULL SECTIONS Full section views cut all the way across the object. Full Section Views can be placed on the same page or on another page. The Cutting Plane and Arrows always are displayed. HALF SECTIONS Half Section Views are used primarily on symmetrically shaped objects (where both halves are the same). They are a great shortcut because you can depict the inside and outside of the object all in one view. Half Section Views can be placed on the same page or on another page. If the view is displayed on another page, the Cutting Plane and Arrows always are displayed.

Brocken-out Section

When it is necessary to expose only a small portion of the internal shape of an object but not enough to warrant a full or half section, use a broken-out section. Define a broken-out section with a break line or a combination of a break line and a centerline.

CONVENTIONAL BREAKS Conventional Breaks are a way of depicting a very long object without showing the entire length. It is often used for objects like rods, tubing/piping or wooden objects

Revolved Sections Revolved sections are cross sections of an elongated form or object rotated toward the plane of projection to show its shape or contour. Drop a cutting plane perpendicular to the axis of the object and revolve the plane 90-degrees around a centerline and at a right angle to the axis. Retain the true shape of the revolved section regardless of the direction of the lines in the view. Superimpose the revolved section over the view and remove all original surface lines.

More examples

Removed Sections A removed section is a section or partial section not directly projected from the view containing the cutting plane and not revolved or turned from its normal orientation. A removed section does not align with any other view, but, sometimes appears on centerlines extended from the section cuts. Use removed sections to show small details and to facilitate dimensioning. This reason, they are often drawn in enlarged scale. Label removed sections alphabetically from left to right on the drawing and corresponding to the letters at the end of the cutting plane line. Precede the letters with the abbreviation SECT or SECTION. To avoid confusion, do not use the letters I, O, and Q. When you draw the removed section enlarged, indicate the larger scale beneath the section title.

Removed section of an Allen wrench using: A. The cutting plane, and B.

The aligned section method.

Aligned Sections

Aligned sections use an angled cutting plane to pass through angled features. The plane and feature are then imagined to be revolved into the original plane and the section projected from there.

Offset Sections An offset section results when you bend the cutting plane to show internal features that are not in a straight line. The offsets or bends in the cutting plane never show in the sectional view. Cutting plane lines in an offset section appear as thick, dashed lines.

Cross Hatch Symbols

Cast Iron (General Use)

White Metal (Zinc)

Sand

Steel

Magnesium, Aluminum

Titanium

Felt, Leather, & Fiber

Bronze, Brass, etc.

Concrete

Marble, Slate, Glass, etc.

Water, Liquids

Wood; Cross Grain With Grain

Surface finish

Ra Value v/s conventional symbols:

Direction of lay:

Requirement for machining

The Symbol indicates the surface finish requirements and shows a machining allowance requirement of 3mm on all surfaces.

Machining Allowance

Symbol for surface texture all component surfaces

The Symbol indicates that all of the component surfaces are to be machined...

Location of Surface Texture Symbols

The shows typical locations for surface texture symbols...

Surface roughness produced by common production processes

Process Flame Cutting Snagging Sawing Planing, Shaping Drilling Chemical Milling Elect. Discharge Mach. Milling Broaching Reaming Electron Beam Laser Electro-Chemical Boring, Turning Barrel Finishing Electrolytic grinding Roller Burnishing

50 25 12.5 (2000) (1000) (500)

6.3 (250)

3.2 (125)

1.6 (63)

0.8 (32)

0.4 (16)

0.2 (8)

0.1 (4)

0.05 (2)

0.025 (1)

0.012 (0.5)

Roughness Average Micrometers µm (Micro inches µ in.)

Surface roughness produced by common production processes

Process

50 25 12.5 (2000) (1000) (500)

6.3 (250)

3.2 (125)

1.6 (63)

0.8 (32)

0.4 (16)

0.2 (8)

0.1 (4)

0.05 (2)

0.025 (1)

0.012 (0.5)

Grinding Honing Electro-Polish Polishing Lapping Superfinishing Sand Casting Hot Rolling Forging Perm Mold Casting Investment Casting Extruding Cold Rolling, Drawing Die Casting

Roughness Average Micrometers µm (Micro inches µ in.)

Welding symbol

Coordinate Dimensioning and Tolerance

The collective process of modeling, defining and describing geometric sizes and feature relationships, and providing all of the required technical information necessary to produce and inspect the part is called dimensioning and Tolerancing. The current National Standard for dimensioning and Tolerancing in the United States is ASME Y14.5M - 1994.

Drawing Notes

Notes should be concise and specific. They should use appropriate technical language, and be complete and accurate in every detail. They should be authored in such a way as to have only one possible interpretation. General Notes DRAWN IN ACCORDANCE WITH ASME Y14.5M - 1994 REMOVE ALL BURRS AND SHARP EDGES ALL FILLETS AND ROUNDS R .06 UNLESS OTHERWISE SPECIFIED

Local Notes 4X

 8.20

M10 X 1.25 82º CSK

10

1.5 X 45º CHAM

Arrowheads

Arrowheads are used as terminators on dimension lines. The points of the arrowheads on leader lines and dimension lines must make contact with the feature object line or extension lines which represent the feature being dimensioned. The standard size ratio for all arrowheads on mechanical drawings is 3:1 (length to width). 200

R 8.5

Of the four different arrowhead types that are authorized by the national standard, ASME Y14.2M – 1994, a filled arrowhead is the highest preference.

1st

2nd

3rd

4th

Dimension Lines and Extension Lines

Extension lines overlap dimension lines (beyond the point of the arrowheads) by a distance of roughly 2-3mm

1.75 There should be a visible gap (~1.5 mm) between the object lines and the beginning of each extension line.

1.06

Dimensions should be placed outside the actual part outline. Dimensions should not be placed within the part boundaries unless greater clarity would result.

Placement of Linear Dimensions Order of Preference

2.562

Arrows in / dimension in

1.250

Arrows out / dimension in

.750

.500

Arrows in / dimension out

Arrows out / dimension out

When there is not enough room between the extension lines to accommodate either the dimension value or the dimension lines they can be placed outside the extension lines as shown in the fourth example

Dimensioning

Types of Dimensioning: • Parallel Dimensioning: Parallel dimensioning consists of originating from one projection line.

several

dimensions

• Superimposed Running Dimensions: Superimposed running dimensioning simplifies parallel dimensions in order to reduce the space used on a drawing. The common origin for the dimension lines is indicated by a small circle at the intersection of the first dimension and the projection line. In general all other dimension lines are broken. The dimension note can appear above the dimension line or in-line with the projection line.

• Chain Dimensioning: Chains of dimension should only be used if the function of the object won't be affected by the accumulation of the tolerances. (A tolerance is an indication of the accuracy the product has to be made to. Tolerance will be covered later in this chapter).

• Combined Dimensions: A combined dimension uses both chain and parallel dimensioning.

• Dimensioning by Co-ordinates: Two sets of superimposed running dimensions running at right angles can be used with any features which need their centre points defined, such as holes.

• Simplified dimensioning by co-ordinates: It is also possible to simplify co-ordinate dimensions by using a table to identify features and positions.

Fundamental rules of dimensioning

• Each dimension shall have a tolerance, except for those dimensions specifically identified as reference, maximum, minimum, or stock (commercial stock size). The tolerance may be applied directly to the dimension (or indirectly in the case of basic dimensions), indicated by a general note, or located in a supplementary block of the drawing format • Dimensioning and tolerance shall be complete so there is full understanding of the characteristics of each feature. Neither scaling (measuring the size of a feature directly from an engineering drawing) nor assumption of a distance or size is permitted • Each necessary dimension of an end product shall be shown. No more dimensions than those necessary for complete definition shall be given. The use of reference dimensions on a drawing should be minimized • Dimensions shall be selected and arranged to suit the function and mating relationship of a part and shall not be subject to more than one interpretation • The drawing should define a part without specifying manufacturing methods • Dimensions should be arranged to provide required information for optimum readability. Dimensions should be shown in true profile views and refer to visible outlines

•

Wires, cables, sheets, rods, and other materials manufactured to gage or code numbers shall be specified by linear dimensions indicating the diameter or thickness. Gage or code numbers may be shown in parentheses following the dimension

•

A 90o angle applies where center lines and lines depicting features are shown on a drawing at right angles and no angle is specified

•

Unless otherwise specified, all dimensions are applicable at 20°C (68°F). compensation may be made for measurements made at other temperatures

•

All dimensions and tolerances apply in a free state condition. This principle does not apply to non-rigid parts

Reference Dimensions

Reference Dimension Symbol (X.XXX)

2.250 1.000

(.750)

• .500

• •

.500 1.250 .500

• (.750)

Reference dimensions are used on drawings to provide support information only. They are values that have been derived from other dimensions and therefore should not be used for calculation, production or inspection of parts. The use of reference dimensions on drawings should be minimized.

Location of Dimensions

Shorter (intermediate) dimensions are placed closest to the outline of the part, followed by dimensions of greater length. Dimensions nearest the object outline should be at least .375 inches (10 mm) away from the object, and succeeding parallel dimension lines should be at least .250 inches (6 mm) apart.

.250 (6mm) Minimum Spacing

4.375 1.438

1.250

1.000

.375 (10mm) Minimum Spacing 1.875

1.062

.688

2.312

•

Dimensions should be placed outside the actual part outline

Basic Dimensioning – Good Practice 4.375 1.438

1.250

1.000 1.875 1.062

.688 2.312 Extension lines should not cross dimension lines if avoidable

1.250

1.438

In-line dimensions can share arrowheads with contiguous dimensions

1.000 1.875 1.062

.688

2.312 4.375

BETTER

Diameter Dimensions Holes and cutouts

1.375

.625 THRU .250

.62

1.375

.250 x .62 DP

Diameter Dimensions Shafts and Holes •

Whenever it is practical to do so, external diameters are dimensioned in rectangular (or longitudinal) views. Cylindrical holes, slotted holes, and cutouts that are irregular in shape would normally be dimensioned in views where their true geometric shape is shown. .25 THRU

1.25 .75

2.00

Placement with Polar Coordinates To dimension features on a round or axis symmetric component

18º 3X 6X

.562

.188

18º 3.50 .875

18º

18º

18º

18º

Radial Dimensions To indicate the size of fillets, rounds, and radii

R.312 R14.25

R.750

R.312

R.562

Angular Dimensions •To indicate the size of angular details appearing as either angular or linear dimensions. 92 92Þ º

Length of Chord

35

90 or

103

Length of Arc º 2 x 45 2 x 45Þ

or 2 x 2 CHAM

Chamfers

or

63Þ

50

63º 95

Alternate

“Times” and “By” Symbol: X 8X

.250 THRU

•

•

• .12 X 45º CHAMFER

.375 CSK .562 X 82º

The X symbol can also be used to indicate the word “by”. For instance, when a slot that has a given width by a specified length, or a chamfer that has equal sides (.12 X .12). When used to imply the word ‘by’, a space must precede and follow the X symbol. If the same feature is repeated on the drawing (such as 8 holes of the same diameter and in a specified pattern), the number of times the instruction applies is called out using the symbol X.

Drilled Holes •Normally specified by diameter and depth (or THRU note used).

45

12.5

14 THRU

25

90

50

12.5

12

2x 12 THRU

32

Specify reaming if accuracy/finish is important.

25

90

12

ASME/ANSI Hole Depth Symbol

Depth or Deep Symbol*

•

Features such as blind holes and counterbores, must have a depth called out to fully describe their geometry.

EXAMPLE .625 .375 .625

OR

.375

* This symbol is currently not used in the ISO standard. It has been proposed.

ASME/ANSI Countersink Symbol Countersink Symbol*

EXAMPLE

•

The symbol denotes a requirement for countersunk holes used to recess flathead screws. The height of the symbol is equal to the letter height on the drawing, and the included angle is drawn at 90º. Note that this symbol is not used in the ISO (international) standard.

.375 .562 X 90º

* This symbol is currently not used in the ISO standard. It has been proposed.

ASME/ANSI Counter bore Symbol

•

Counterbore Symbol*

This symbol denotes counterbored holes used to recess machine screw heads.

EXAMPLE .312 .375 .562

.312 .562

.375

OR * This symbol is currently not used in the ISO standard. It has been proposed.

Counter bores and Countersinks – ISO Standard

12.5

Socket Cap Head or Machine screws

2x  8.8 THRU  14 C BORE x 8.2 DP

50 32

25

90

12.5

Flat Head

12

2x  8.8 THRU  15 C SUNK X 90°

50 32

25

90

12

Screw Threads M 16 x 2

ISO specify metric only:

M 16 x 2 - 4h - 5H ISO metric designation

Nominal Diameter (mm)

American Unified Threads:

Thread Pitch(mm)

Class of fit of mating thread (optional) Class of fit of this thread (optional)

3/4 - 10 - UNC

3/4 - 10 - UNC - 2A Nominal Diameter (inches)

Threads per inch Thread Series UNC = Unified Coarse UNF = Unified Fine

Note: Use standard screw sizes only

Thread Type (optional) A=External B=Internal Class of fit (optional)

Threads and Screw Fastening Always a 'Clearance Hole' (typically screw major Dia. + 10%) in at least one component in a screw fastened joint.

Example Assembly

Base

'A'

'A'

3 - M12 Hex. Screws Lid

Section 'A'-'A'

Threads and Screw Fastening (cont.)

Base Detail

'A'

'A'

3 Holes 10.3x 25 DP M12x1.75 x 15 DP MIN EQ SP on 120 PD

Section 'A'-'A'

Threads and Screw Fastening (cont.) Lid Detail

'A'

'A'

3 Holes 12.7 THRU  EQ SP on   120 PD

Section 'A'-'A'

Dimensioning strategy: •

Break up into simple shapes

•

Dimension each simple shape (size)

•

Dimension position of each shape (location)

•

Check for redundant dimensions

•

Do in rough form first

•

Plan for positioning of dimensions on final drawing

Size one feature

Size all features

Locate one feature

Locate all features

Dos & Don’ts of dimensioning:

Dos & Donts of dimens ioning

Tolerances

important to interchangeability and provision for replacement parts

•It is impossible to make parts to an exact size. The tolerance, or accuracy required, will depend on the function of the part and the particular feature being dimensioned. Therefore, the range of permissible size, or tolerance, must be specified for all dimensions on a drawing, by the designer/draftsperson. •Nominal Size: is the size used for general identification, not the exact size. •Actual Size: is the measured dimension. A shaft of nominal diameter 10 mm may be measured to be an actual size of 9.975 mm. •General Tolerances: •In ISO metric, general tolerances are specified in a note, usually in the title block, typically of the form: "General tolerances ±.25 unless otherwise stated". •In English Units , the decimal place indicates the general tolerance given in the title block notes, typically: •Fractions = ±1/16, .XX = ±.01, .XXX = ±.005, .XXXX = ±0.0005, •Note: Fractions and this type of general Tolerancing is not permissible

Specific Tolerances Specific Tolerances indicate a special situation that cannot be covered by the general tolerance. Specific tolerances are placed on the drawing with the dimension and have traditionally been expressed in a number of ways: +0.05 40 - 0.03 Bilateral Tolerance

40.01 +0.04

40.05 39.97

Unilateral Tolerance

Limit Dimensions

•Limits are the maximum and minimum sizes permitted by the the tolerance. All of the above methods show that the dimension has: • a Lower Limit = 39.97 mm • an Upper Limit = 40.05 mm • a Tolerance = 0.08 mm •Manufacturing must ensure that the dimensions are kept within the limits specified. Design must not over specify as tolerances have an exponential affect on cost.

Assembly Drawing • Assembly Drawings: The assembly /sub-assembly drawings are drawings of discrete sub-systems showing in some detail how the component items fit together. Typical assembly drawings include gearbox drawings, roller drawings, guard system drawings. Typical assembly drawing contains the following; • At least three orthographic views with sections as needed to clearly show all of the details and their relative positions. • Overall and detail dimensions • The weight/mass of the assembly/sub-assembly will be noted. • A parts list identifying all of the component details with quantities and materials and supply details. • A list of reference drawings and notes identifying the relevant codes and specifications and testing requirements. • Include a note explaining the required assembly operation and give the dimensions for the alignment or location of the pieces. • An assembly drawing should not be overloaded with detail. • Include reference letters and numbers representing the different parts. These part numbers usually enclosed by circles with a leader pointing to the piece.

Assembly Drawing • A unit assembly (subassembly) is a drawing of a related group of parts and used to show the assembly of complicated machinery for which it would be practically impossible to show all the features on one drawing. To illustrate; headstock, tailstock, and gearbox unit assemblies should be included in the drawing of a lathe. • An outline assembly is used to describe the exterior shape of a machine or structure, so it contains only the primary dimensions. If it is made for catalogs or illustrative purposes, dimensions are often omitted. They are also called as installation drawings. • An assembly working drawing includes all the necessary information for producing a machine or structure on one drawing. This requires providing adequate orthographic views together with dimensions. • A diagram drawing is an assembly showing ,symbolically, installation of equipment and often made in pictorial form. • The bill of material is a tabulated list placed either on the assembly drawing or on a separate sheet. The list gives the part numbers, names, quantities, material and sometimes stock sizes of raw material, detail drawing number, etc. The term "bill of material" is usually used in structural and architectural drawing whereas the term "part list" is used in machine-drawing practice.

Assembly Drawing

Assembly Drawing

Features of an Assembly Drawing Dimensions Detailed dimensions required for manufacture are excluded from assembly drawings. But overall dimensions of the assembled object are usually indicated. If the spatial relationship between parts if important for the product to function correctly then these should also be indicated on the drawing. For example indicating the maximum and minimum clearance between two parts. Internal Parts If there are internal assemblies, sectional views should be used. Parts list Each part is given a unique number, indicated on the drawing by a circle with the number in it and a leader line pointing to the part. The leader line terminates in an arrow if the line touches the edge of the component, or in a circle if the line terminates inside the part. A table of parts should be added to the drawing to identify each part, an example of a parts list is shown below: The first three items; Item No., Description, and Quantity should be completed for every distinct part on your drawing. (i.e. the number of duplicate parts are recorded in the quantity). The material is used for components that are being made within the company. The Remarks column is useful for specifying a manufacturers part number when using bought-in parts. Item No.

Description

Qty

Material

Remarks

Exploded Drawing An exploded view is a representative picture or diagram that shows the components of an object slightly separated by distance, or suspended in surrounding space in the case of a three-dimensional exploded diagram, as if there had been a small controlled explosion emanating from the middle of the object which separated all of the parts of that object an equal distance away from their original locations. Exploded diagrams are common in descriptive manuals showing parts placement, or parts contained in an assembly or sub-assembly. Usually such diagrams have the part identification number and a label indicating which part fills the particular position in the diagram. Many spreadsheet applications can automatically create exploded diagrams, such as exploded pie charts.

Exploded Drawing

Drawing for sheet metal parts Typical sheet metal parts contain one form view, flat view, Isometric view and other necessary views. Form view: This view represents details in the bent or form condition Flat view: This view represents details of blank development along with the necessary holes and cut features Isometric view: This view represents about 3D image of the sheet metal part

Isometric View Formed View

Flat View

Drawing for forging parts Forging Forging is the working of metal by plastic deformation. It is distinguished from machining, the shaping of metal by removing material, such as by drilling, sawing, milling, turning or grinding, and from casting, wherein metal in its molten state is poured into a mold, whose form it retains on solidifying. The processes of raising, sinking, rolling, swaging, drawing and upsetting are essentially forging operations although they are not commonly so called because of the special techniques and tooling they require. Forging results in metal that is stronger than cast or machined metal parts. This is because during forging the metal's grain flow changes into the shape of the part, making it stronger. Some modern parts require a specific grain flow to ensure the strength and reliability of the part.

Drawing for casting parts

Engineering Standards

• • • •

Introduction to standards Standards Organizations Knowledge of some International Standards Examples of Standards

Introduction to standards What are standards? Just like any other language, the grammar of this engineering language is defined by various standards across globe. These standards talk about dimension styles, tolerance, sheet sizes, etc. In short these standards define each & every thing required to create any basic engineering drawing

History and Evolution of Standards The industrial revolution in 19th century forced the world to create the standards for drawing creation. Mainly it started with military application. Then it was adapted by all other industries. Almost every nation has it’s own standards.

Usage of standards These standards are used in all engineering streams, Mechanical, Civil, Chemical, Automobile, electronics, etc

Types of standards Drawing standards, welding standards, safety standards, construction standards, etc

Standards Organizations Standards Developing Organizations (SDOs) All over the world there are number of organizations which are involved in developing different standards. • • • • • •

ASME: American Society of Mechanical Engineers ANSI: American National Standards Institute BIS: Bureau of Indian Standards BSI: British standards DIN: Deutsches Institute for Norms JIS: Japanese Industrial Standards

Scope of work • • • • •

Creating standards Standards publication Training about standards Assessment & certification Product testing

Standards development process • • • • •

Identifying the requirements Creating a draft copy of the standard Deliberation by authorized panel Establishment of the standard Promotion of the standards

Knowledge of some International Standards ASTM: AMERICAN STANDARDS FOR TESTING ASTM provides standard for ferrous-non-ferrous materials specification & material testing. Used in US.

API: AMERICAN PETROLEUM INSTITUTION Widely

followed

by

petrochemical

industry

&

Chemical

industry

ASME: AMERICAN SOCIETY OF MECHANICAL ENGINEERS ASME provides codes and standards for various mechanical elements. Pressure vessel codes by ASME are used by all industrial nations.

AIAA:

AEROSPACE INDUSTRIES ASSOCIATION OF AMERICA This standards service includes National Aerospace Standards (NAS) and metric standards (NA Series)

BSI: BRITISH STANDARDS INSTITUTION British standards provide standards for various machine elements, material specification and testing, sealants and automotive components

Knowledge of some International Standards DIN standards: Standards by Germany widely followed across Europe Japan and America.

JIS: JAPANESE INDUSTRIAL STANDARDS Provides standards and codes for almost all major engineering divisions.

ISO: INTERNATIONAL STANDARDS ORGANIZATION BIS: BUREAU OF INDIAN STANDARDS SAE: SOCIETY OF AUTOMOTIVE ENGINEERS Provides standards for Aerospace, Off-highway vehicles and automobile components design.

Examples of Standards • GD&T Standards • Drawings and Terminology • Measurement standards • Tooling Standards • Welding standards • Refrigeration and Air Conditioning Standards • Hydraulics Standards • Aerospace Standards • Manufacturing standards • Automobile Standards

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