Engineering DRG practice - A Refresher Course - PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Introduction: What is Engineering Drawing? • • • • DRG is the language of Engineers. It is the principal means of communication in ENGG. It is the method used to impart ideas, convey information, specify shape, configuration and size. It is an international language and is bound, like any other language, by rules and conventions. PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice • Projections • DRG standards • Sheet sizes • Folding • Filing PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Picture planes : PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Projections: • Projection is the representation on a plane surface the image of an object observed by a viewer. • In graphical language shape is described by projections as geometric figures. • The image of the object, formed by rays of sight (lines of projection) taken in some particular direction from the object on to a plane form a view in any DRG. PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Orthographic projection: • It is a particular type of projection in which the object’s image is projected onto three mutually perpendicular planes. • If the viewing point (eye) is at an infinite distance from the object such that the projection lines are parallel to one another and perpendicular to the picture plane, the projection obtained is called Orthographic projection. • It represents the exact shape of a three dimensional object on a two dimensional sheet in two or more views. PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Orthographic projection: • These contd… views require good imagination to interpret and visualize the details of objects • This method is universally used in ENGG DRG to represent objects. • Orthographic views are required for the manufacture of objects and machine parts. • Front view, top view and Side view of an object are the principal Orthographic views. • Two types of Orthographic projections are used: - First angle projection - Third angle projection PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice First angle projection : PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice First angle projection : 1. 2. 3. 4. 5. Object is kept above the H.P and in front of V.P. (i.e. in the first quadrant). The object is projected on the V.P. and the H.P. The object lies between the observer and the plane of projection. H.P. is then rotated in clockwise direction through 900 such that the V.P. and the H.P. are brought in line with each other. In this projection method, the top view appears below the front view and left side view appears on the right of the front view. PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Third angle projection : PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Third angle projection : 1. 2. 3. 4. 5. 6. Object is kept behind the V.P. and below the H.P. (i.e. in the third quadrant). The projection plane lies between the observer and the object. The projection planes are assumed to be transparent. The object is projected on the V.P. and the H.P. H.P. is then rotated in clockwise direction through 900 such that the V.P. and the H.P. are brought in line with each other. In this projection method, the top view appears above the front view and left side view appears on the left of the front view. PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Other types of projections: • Oblique • Isometric • Perspective Note: 1. Oblique and Isometric views are often used in the preparation of maintenance manuals and parts lists of ENGG equipment / assemblies. 2. Perspective views are mostly used by artists. PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Other types of projections: Oblique Projection: • It has two axes at right angles to each other. contd… • The third axis may be at any angle to the horizontal, 300 or 450 are being generally used. • The measurement along the third axis are halved. PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Other types of projections: contd… Isometric Projection: • It is a special type of pictorial projection showing the three DIM of an object in one view. • It conveys the real shape of the object. • Isometric projection of any object is the single orthographic projection of the object placed so that all its three axes are equally inclined to the plane of projection. • In this position, all the three sides of the object are exposed to the viewer. • Isometric scale = 0.815 x True length PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice DRG Standards PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice The following are some of the BIS standards relevant to Engineering DRG practice : • • • • • • • These standards are reviewed and revised from time to time IS:10714 - 1983 – General principles of presentation on technical drawings IS:9609 (part1)-1983 – Lettering on technical drawings (part1 English characters) IS:10718-1983 – Method of dimensioning and tolerancing on technical drawings IS:11667 – 1991 – Technical drawings - Linear and angular tolerancing - Indication on drawings IS:11669 -1986 – General principle of dimensioning on technical drawings IS:8000(Part1)-1985 - Geometrical tolerancing on technical drawings (part 1: Tolerancing of form, orientation, location and run-out and appropriate geometrical definitions) PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice BIS standards for technical DRG: • • • • • • • • contd… IS:8000 (Part2)-1976 - Geometrical tolerancing on technical drawings (part 2: Maximum material principles) IS:8000 (Part3)-1985 - Geometrical tolerancing on technical drawings (part 3: Dimensioning and tolerancing of profiles) IS:10721 – 1983 - Datum and datum systems for geometrical tolerancing on technical drawings IS:11158-1984 - Proportions and dimensions of symbols for geometrical tolerancing used in technical drawings IS:2709-1964 - Guide for selection of fits IS:919:1963 - Recommendations for Limits and Fits for Engg IS:3073 -1967 - Assessment of surface roughness IS:10719 - Method of indicating surface texture on tech DRG PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice BIS standards for technical DRG: • • • IS: 813- 1986 - Scheme of symbols for welding IS: 10711-1983 - Sizes of DRG sheets IS: 1064 - 1961 - Specification for paper sizes. contd… PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Sheet sizes PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice DRG sheet size Preferred DRG sheet sizes are as follows: Sheet size A0 A1 A2 A3 A4 Trimmed size in mm 841 X 1189 594 X 841 420 X 594 297 X 420 210 X 297 • The surface area of two successive preferred sizes are in the ratio of 1:2. • DRG sheet sides of each size are in the ratio of 1:√2 • The surface area of the basic size A0 is 1 sq. m PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Preferred DRG sheet sizes Similarity of formats Relationship between two sides Successive format sizes PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Title Block Title block should contain the following information: 1. 2. 3. 4. 5. 6. Title of the DRG DRG No. & sheet No. Scale Projection symbol Name of the organisation Dated initials of the personnel designing, checking, standard and approved The size of the title block is uniform for all sizes. Note: PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Recommended scales for Engineering DRG: Full size 1:1 Reduced scale 1:2 1:5 1:10 1:20 1:50 1:100 1:200 1:500 1:1000 1:2000 1:5000 1:10000 Enlarged scale 50:1 20:1 10:1 5:1 2:1 PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Grid reference on DRG sheet: • It permits easy location on the DRG of details, additions, modifications etc. How & when to use Grid reference ? eg: C7 E5 1. PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Conventional lines and applications Description Continuous - thick Continuous - thin ( Straight and curved) A B Line Applications A1 Visible outline A2 Visible edges B1 Imaginary lines of intersection B2 DIM lines B3 Projection lines B4 Leader lines B5 Hatching B6 Out lines of revolved section in place B7 Short centre line C1 Limits of partial or interrupted views and sections, if the limit is not a chain thin line D1 Continuous thin free hand. Continuous thin (Straight) with zig zags. C D PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Conventional lines and applications Description Dashed thick Dashed thin Chain thin E F G Line E1 E2 F1 F2 Applications Hidden outlines Hidden edges Hidden outlines Hidden edges G1 Centre lines G2 Lines of symmetry G3 Trajectories H1 Cutting planes Chain thin, thick at ends H and changes of direction Chain thick J J1 Indication of lines or surfaces to which a special requirement applies PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Conventional lines and applications Type of line Chain thin double dashed K Illustration Application K1 Outlines of adjacent parts K2 Alternative and extreme positions of movable parts K3 Centroidal lines K4 Initial outlines prior to forming K5 Parts situated in front of the cutting plane Line thicknesses recommended: 0.18, 0.25, 0.35, 0.5, 0.7, 1.0, 1.4 and 2.0 Note: Due to reproduction problems 0.18 is normally avoided • PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Lettering PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Lettering proportions PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Lettering proportions PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Lettering proportions PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Different characteristics of lettering type ‘A’ PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Different characteristics of lettering type ‘B’ PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice DRG sheet Folding and Filing: • There are two methods of folding of DRG prints. 1. 2. The first method is for DRG prints to be filed or bound. The second method is intended for prints to be kept individually in filing cabinet. All large prints of sizes higher than A4 are folded to A4 sizes. The title block of a folded print as it appears in the bottom right corner shall be visible outer most after folding. Suitable folding marks are to be introduced in the DRG sheets as guide for folding purpose. Basic principles: § § § PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Folding of prints for filing or binding PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Folding of prints for storing in filing cabinet PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice • Types of drawings • Contents of a drawing PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Types of drawings 1. Design layout: Shows the arrangement of various assemblies and parts in their correct orientation and location as envisaged by the designer and drawn to scale. 2. Assembly drawing: Contains all the components and sub-assemblies which are shown in the correctly fitted condition and demanded item wise and number wise. The specifications for standard parts and proprietary items are also given in the assembly drawing. 3. Item List: Accompanies the assembly drawings as a separate sheet/sheets. Some times this is incorporated in the assembly drawing itself. PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Types of drawings 4. Part drawing: Contains enough technical data to fully define the individual component and facilitate its manufacture. 5. Manufacturing drawing: Contains process information for the manufacture of an assembly or individual component. It is often made as a separate drawing. In some cases process information is carried in the product drawing itself whether assembly or component. PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Types of drawings 6. Technical Documents: These are strictly speaking not drawings but they come within the purview of a product design office. Some of them contain drawings /sketches in 2D or 3D form to facilitate easy understanding by the user. These include: • • • • • • • • Product specifications Consolidated Complete Equipment Schedule (CCES) Operators/users manual Maintenance/repair manuals Illustrated Spare Parts List (ISPL) Manufacturer’s Recommended List of Spares (MRLS) Maintenance Scales (MS) Training Charts PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Contents of a drawing • • A DRG contains technical information in the form of Orthographic views, text and symbols. It gives detailed data with regard to dimensions, permissible deviations, material, surface finish, protective coatings, assembly procedures, part details, specifications, process information, etc depending upon the type of drawing. Drawings are made in standard sheet sizes from A4 to A0 with the title block of the organisation and numbered according to a specific system followed. The title block also contains information in type of projection method used, scale and standard notes. • PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Dimensions and Tolerances PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Definition of Dimension : • It is a numerical value expressed in appropriate units of measurement and indicated graphically on technical drawings with lines, symbols and notes. PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Dimension Classifications: • • • • • Functional dimensions: Any DIM that is essential for the functioning of the component or the equipment. Non Functional dimensions: Auxiliary dimensions: It does not govern production or Inspection and is derived from other values shown on drgs. PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Functional, non-functional and auxiliary DIM PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice System of dimensioning: 1. 2. 1. • 2. • • Method 1 Method 2 Method 1 : - Aligned system DIM values are so placed that they may be read from the bottom or right hand edge of the DRG Method 2 : - Unidirectional system DIM values are so placed that they may be read from the bottom edge DRG sheet It is more convenient in large size DRG PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Method 1 : - Aligned system PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Method 2 : - Unidirectional system PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Angular dimensions PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Elements of dimensioning: 1. 2. 3. 4. 5. 6. Projection line or Extension line Dimensional line Leader line Dimension line termination The origin indication Dimension itself PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Elements of dimensioning: PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Arrangement and indication of dimensions: 1. 2. 3. 4. 5. Chain dimensioning Parallel dimensioning Super imposed running dimensioning Equidistant features Dimensioning by coordinates PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Chain dimensioning PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Parallel dimensioning PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Super imposed running dimensioning PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Equidistance feature PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Dimensioning by coordinates PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Addition of letters and symbols to Dimensions: Ø R SR - Diameter - Radius - Square - Spherical radius SØ - Spherical diameter Note: • The symbol should be written before the dimension PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Limits, Fits and Tolerances Limits: • Limits are the two extreme permissible sizes between which the actual size is contained. eg:30±0.02 Fit: • The relation between two parts where one is inserted into the other with a certain degree of tightness or looseness is known as fit. PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Types of fit: • • • Clearance fit Interference fit Transition fit Clearance fit: • A positive allowance between the largest possible shaft and the smallest possible hole. Clearance fit- sub classifications: 1. 2. 3. 4. 5. Slide fit Easy slide fit Running fit Slack running fit Loose running fit PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Interference fit: • A negative allowance or interference between the largest possible hole and the smallest possible shaft. Interference fit-sub classifications: 1. Shrink or force fit 2. Heavy drive fit 3. Light drive fit Transition fit • They cover cases between the first two classes Condition: LL on shaft < LL on hole HL on shaft > LL on hole PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Basic size, deviations and tolerances PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Transition fit sub-classification: 1. 2. 3. • Force fit Tight fit Wringing fit Tolerance is the difference between high limit and low limit of size. Bilateral tolerance: If tolerance is applied on both sides of the basic size, then it is called bilateral tolerance. eg:30±0.02 Tolerance = High limit - Low limit = 30.02 – 29.98 = 0.04 Tolerances: Types of tolerances: 1. • PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice 2. Unilateral tolerance: If tolerance is applied on one side of the basic size, then it is called Unilateral tolerance. eg:30- 0.02 Tolerance = High limit - Low limit = 30.0 – 29.98 = 0.02 Allowances: • An intentional difference between the hole DIM and shaft DIM for any type of fit is called the allowance. The algebraic difference between actual size and the basic size of a component. Deviation: • PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Disposition of tolerance zones for the three class of fit PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Different methods of specifying tolerances PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Different methods of specifying Fits on assembled parts -0.020 -0.041 PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Different methods of specifying tolerances for angular DIM PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Types of deviation: • • 2. • Upper deviation: The algebraic difference between max. limit and the basic size Lower deviation: The algebraic difference between min. limit and the basic size It is one of the two deviations which is conveniently chosen to define the position of the tolerance zone in relation to zero line Fundamental deviation: • PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Hole basis system: • In this system, the hole DIM (whose lower deviation is zero & Symbol H) is kept constant and different types of fit are obtained by varying the size of the shaft. Most widely used • Shaft basis system: • In this system the shaft DIM (whose upper deviation is zero & Symbol h) is kept constant and different types of fit are obtained by varying the size of the hole. PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice The Shaft basis and the Hole basis system PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Tolerance bands for different shafts & holes PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Selection of tolerance zones PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Some of the select ISO fits- Hole basis: Clearance fit: H6g5 H7g6 H8g7 H6f6 H7f7 H8f8 H8e7 H8e8 H9e9 normal running close running precision running PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Some of the select ISO fits- Hole basis: Clearance fit: H8d8 H8d9 H9d9 H8c8 H8b8 H9c9 H11c11 H11c9 H11b9 slack running or positional fit loose running PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Some of the select ISO fits- Hole basis: Location and assembly fit: H6h5 H6h6 H7h6 H7h7 H8h7 H8h8 Normal location Close location Precision location contd… PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Some of the select ISO fits- Hole basis: Location and assembly fit: H9h8 H9h9 H11h9 H11h11 H8h9 Positional fit Slack Assy Loose location contd… PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Some of the selected ISO fits- Hole basis: Transition and Interference fit: H6j5 H7j6 H8j7 H6k5 H7k6 H8k7 H6m5 H7m6 H8m7 H6p5 H7p6 PDF created with pdfFactory trial version www.pdffactory.com Clearance transition True transition Interference transition Press fit Engineering DRG practice Standard features and components PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Standard features and components PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Standard features and components PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Standard features and components PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Standard features and components PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Standard features and components PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Welding Symbols PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Welding Symbols PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Welding Symbols PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Welding Symbols PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Standard Abbreviations PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Standard Abbreviations Term Across corners Across flats Alternating current Alteration Ampere Ampere-hour Approved Approximate Arrangement Assembly Auxiliary Abbreviation A/C A/F ac ALT A Ah APPD APPROX ARRGT ASSY AUX Bearing Brake horse power Brinell hardness PDF created with pdfFactory trial version www.pdffactory.com BRG bhp HB Engineering DRG practice Standard Abbreviations Term Cast iron Centres Centre line Centre of gravity Centre to centre Chamfered Checked Cheese head Circular Pitch Circumference Connected Continued Abbreviation CI CRS CL CG C/C CHMED CHKD CH HD CP Oce CONN CONTD PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Standard Abbreviations Term Constant Counter bore Countersunk Countersunk head Cubic centimeter Cubic Metre Cubic millimetre Cylinder / Cylindrical Degree Celsius Degree Kelvin Diameter (in a note) Diametral Pitch Dimension Direct current Drawing PDF created with pdfFactory trial version www.pdffactory.com Abbreviation CONST C’BORE CSK CSK HD cm3 m3 mm3 CYL 0C K DIA DP DIM dc DRG Engineering DRG practice Standard Abbreviations Term East External et cetera Abbreviation E EXT etc Figure FIG. General Gram Ground level GEN g GL Head Hexagon / Hexagonal Horizontal Horse Power Hour Hydraulic PDF created with pdfFactory trial version www.pdffactory.com HD HEX HORZ hp h HYD Engineering DRG practice Standard Abbreviations Term Indian Standard Inspection / Inspected Inside Diameter Internal Indicated Horse Power Insulation Joule Kilogram Kilolitre Kliometre Kilometre per hour Kilovolt Kilowatt Kilowatt hour Kilovolt-ampere Kilogram force PDF created with pdfFactory trial version www.pdffactory.com Abbreviation IS INSP ID INT ihp INSUL J kg kl km km/h kV kW kWh kVA kgf Engineering DRG practice Standard Abbreviations Term Left Hand Litre Litres per minute Abbreviation LH l l/min Material Machine / Machinery Manufacture / Manufacturing Maximum Mega Newton Mega Pascal Megawatt Metre Metre per second Mechanical Micrometre Millimetre PDF created with pdfFactory trial version www.pdffactory.com MATL M/C MFG max. MN MPa MW m m/s MECH µm mm Engineering DRG practice Standard Abbreviations Term Milliwatt Millivolt Milliampere Minimum Minute (time) Miscellaneous Module Abbreviation mW mV mA min. min MISC m Newton Nominal North Not to scale Number Opposite Outside diameter Pascal PDF created with pdfFactory trial version www.pdffactory.com N NOM N NTS No. OPP OD Pa Engineering DRG practice Standard Abbreviations Term Pitch Circle Diameter Pitch Circle Pressure Quantity Radian Radius Reference Required Revolution per minute Right Hand Rockwell hardness”A” scale Rockwell hardness”B” scale Rockwell hardness”C” scale Second (time) Abbreviation PCD PC P QTY rad R REF REQD rpm RH HRA HRB HRC s PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Standard Abbreviations Term Serial number South Specification Spherical Standard Spot face Stokes Square Square centimetre Square millimetre Square metre Symmetrical Abbreviation Sl No. S SPEC SPHERE STD SF St SQ cm2 mm2 m2 SYM PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Standard Abbreviations Term Thread (in a note) Through (in a note) Temperature Thick Time Tonne Trapezoidal Tolerance Volt Volume Velocity Vickers hardness Watt Abbreviation THD THRU TEMP THK t t Tr TOL V vol v HV W PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Standard Abbreviations Term Watt hour Weight Weight per metre West With respect to Abbreviation Wh WT WT/m W WRT PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Materials, Heat treatment & Protective coatings PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Materials Some typical materials: 1. Wrought steels: • IS:5517, IS: 2062, IS:4454 • Rolled homogeneous Armour plates 2. • 3. • Cast steels: IS:1030, IS:3444, IS:2856, IS:3038 Cast light alloy: IS:617 PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Heat treatment Typical notes: • Harden and temper to 32-35 HRC • Case carburise and harden gear teeth / surfaces marked thus # to 60 - 65 HRC • Stress relieve after welding prior to machining PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Protective Coatings • IS:3618: 1966 – Phosphate treatment of iron and steel for protection against corrosion. Typical note: To be phosphate treated to IS:3618, Class ‘B’ Note : Class ‘B’ indicates – Medium weight 4.3 g/m2 IS:1573:1970 - Electroplated coating on Zinc and on iron and steel • Typical note: To be Zinc plated to IS:1573, Fe Zn 40 Note : Meaning of Fe Zn 40 • 40 – min. local thickness in microns Zn - Zinc coating Fe – Basic metal (iron or steel) IS: 1572-1968 – Cadmium coating on iron and steel Typical note: To be Cadmium coated to IS:1572:1970, Cd8 Note : Meaning of Cd8 – min. local thick 8 microns and Average thick 12microns PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Design office management PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Design office management 1.Purpose of design office: The creation, storage, retrieval and dissemination of engineering information, usually pertaining to specific products/ processes. 2. Relationship between Design and Drawing: Design is the initial creative process whereby the product as envisaged is given shape, size and properties / performance on paper before physical realisation of the end product. 3. Engineering DRG: The document resulting from the design process which gives all relevant information for the manufacture / procurement of the product. PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Design office management KNOWLEDGE SKILLS APPROACH Physical Science ENGG Technology Other Measurement Graphical expression Simulation Experimentation Mathematics Management Interactive ability Communication Decision making Interest Objectivity Open mindedness Creative Imagination Product design PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Design office management DRG Creation: 1. Conventional drafting. • Low capital outlay • Quality and accuracy of the drawings depend upon the individual skill and care of the human element • It is easier for the designers to visualise the product size and configurational aspects • The DIM are not inherently related to what is drawn; hence the probability of errors is more • Redrawing and corrections are tedious • Physical handling is more involved • More storage space is required PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Design office management DRG Creation: 2. Computer Aided drafting. • High capital outlay • High Quality and accuracy • It is difficult for the designers to visualise the product size in 2D mode • The DIM are inherently related to what is drawn; hence the probability of errors is less • Redrawing, scaling and alterations are easier • Digital storage and handling are easier and more acceptable PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Design office management Other aspects: 1. DRG storage and retrieval 2. DRG reproduction 3. DRG numbering system 4. DRG Amendments PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Exercises • DRG sheet print folding and filing • Missing views in Orthographic DRG • Dimensioning • Dimensional tolerancing for specific fits • Geometric tolerancing • Specifying surface finish, heat treatment, protective coating, hardness, welding, symbolic representation, materials etc. • DRG Numbering, item No., Qty, parts list • DRG Amendments, revision etc. PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Exercise PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Engineering Drawing Practice Exercise A view from a DRG is given. 1. 2. 3. 4. Is it an ASSY DRG, a Part DRG or some other type of DRG? Does this view give complete information of the product or not? Identify what it is and give a suitable nomenclature to it. Identify the parts in the DRG, list them out and give suitable nomenclature to these parts. 5. Sketch out one major component and identify the features on it which require geometric tolerancing; mark the geometric tolerancing method. 6. Mark all dimensions essential for the manufacture of the component. 7. Identify and mark the dimensions which would require specific tolerancing. 8. Give suitable material specification with hardness/heat treatment as applicable 9. Give surface finish recommendation where applicable for the component 10. Give a step by step manufacturing process for the component PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Engineering Drawing Practice Exercise PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Engineering Drawing Practice Exercise A shaft and a hole are shown in the DRG. CASE I: Dimension a = 30 mm; both materials are steel. 1. Give tolerances to obtain a precision sliding fit with interchangeability. 2. What is the maximum clearance in the above fit? 3. What is the minimum clearance in the above fit? 4. Give tolerances for a precision location fit with interchangeability. 5. What is the maximum clearance in the fit mentioned in sl.No.4? 6. What is the minimum clearance in the fit mentioned in sl.No.4? 7. What is the maximum interference in the fit mentioned in sl.No.4? 8. What is the minimum interference in the fit mentioned in sl.No.4? PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Engineering Drawing Practice Exercise A shaft and a hole are shown in the DRG. CASE II: Dimension a = 70 mm; both materials are steel. 1. Give tolerances to obtain a precision sliding fit with interchangeability. 2. What is the maximum clearance in the above fit? 3. What is the minimum clearance in the above fit? PDF created with pdfFactory trial version www.pdffactory.com Engineering DRG practice Engineering Drawing Practice Exercise A shaft and a hole are shown in the DRG. CASE III: Dimension a = 30 mm; Bore material Al. alloy and shaft steel. 1. Give tolerances to obtain a precision location fit with interchangeability. 2. What is the maximum clearance in the above fit? 3. What is the minimum clearance in the above fit? 4. What is the maximum interference in the above fit? 5. What is the minimum interference in the above fit? PDF created with pdfFactory trial version www.pdffactory.com