DRWG120-Working_Drawing - Chapter 12 Working Drawing TOPICS...

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Unformatted text preview: Chapter 12 Working Drawing TOPICS Introduction Detail drawing Assembly drawing Assembly section Introduction DEFINITION Working drawing is a set of drawing used during the work of making a product. Working drawing Detail drawing Assembly drawing DEFINITION Detail drawing is a multiview representation of a single part with dimensions and notes. Assembly drawing is a drawing of various parts of a machine or structure assembled in their relative working positions. PURPOSE Detail drawing conveys the information and instructions for manufacturing the part. Assembly drawing conveys 1. completed shape of the product. 2. overall dimensions. 3. relative position of each part. 4. functional relationship among various components. Detail Drawing INFORMATION IN DETAIL DRAWING 1. General information Title block 2. Part’ s information 2.1 Shape description Object’s 2.2 Size description views 2.3 Specifications Notes GENERAL INFORMATION Name of company Title of drawing (usually part’s name) Drawing sheet number Name of drafter, checker Relevant dates of action (drawn, checked, approved etc.) Revision table Unit Scale Method of projection PART’ S INFORMATION Shape Orthographic drawing Pictorial drawing Size Dimensions and Tolerances Specifications Part number, name, number required Type of material used General notes Heat treatment Surface finish General tolerances RECOMMENDED PRACTICE Draw one part to one sheet of paper. If not the case, - apply enough spacing between parts. - draw all parts using the same scale. Otherwise, the scale should be clearly note under each part’s drawing. Standard parts such as bolt, nut, pin, bearing do not require detail drawings. PLACING AN INFORMATION Completed dimension orthographic drawing Part No., Part name, material, Number required Notes Unit, fillets & rounds sizes etc. Title block EXAMPLE : Interpreting detail drawing 1. Orthographic views 2. Dimensions & Tolerances 3. Surface finishing Title block General note Gen. tolerance Projection Revision table Assembly Drawing TYPES OF ASSEMBLY DRAWING 1. Exploded assembly drawings The parts are separately display, but they are aligned according to their assembly positions and sequences. 2. General assembly drawings. All parts are drawn in their working position. 3. Detail assembly drawings All parts are drawn in their working position with a completed dimensions. 1. EXPLODED ASSEMBLY Pictorial representation Pictorial representation Finished product 1. EXPLODED ASSEMBLY Isometric representation Isometric representation 1. EXPLODED ASSEMBLY Orthographic representation Orthographic representation 2. GENERAL ASSEMBLY Pictorial Pictorial Orthographic Orthographic NO DIMENSION AT ALL 2. GENERAL ASSEMBLY Only dimensions relate to machine’s operation are given. Only dimensions relate to machine’s operation are given in tabulated form (not shown). 2. GENERAL ASSEMBLY 3. DETAILED ASSEMBLY (working-drawing assembly) REQUIRED INFORMATION IN GENERAL ASSEMBLY DRAWING 1. All parts, drawn in their operating position. 2. Part list (or bill of materials, BOM) 1. Item number 2. Descriptive name 3. Material, MATL. 4. Quantity required (per a unit of machine), QTY. 3. Leader lines with balloons around part numbers. 4. Machining and assembly operations and critical dimensions related to operation of the machine. PLACING AN INFORMATION - Assembled parts - Reference numbers Part list General notes Title block PART LIST (BOM) Locate above or beside the title block. Fill the table from the bottom. 3 SET SCREW 1 Stainless Steel, M3 HEX SOCK CUP PT 2 SHAFT 1 Stainless Steel 1 SUPPORT 2 Cast Iron NO. PART NAME REQD. MATL. & NOTE PART LIST (BOM) Also can be locate at top-right corner. Fill the table from the top. EXAMPLE : Another allowable place for BOM STEPS TO CREATE ASSEMBLY DRAWING 1. Analyze geometry and dimensions of all parts in order to understand the assembly steps and overall shape of device or machine. 2. Select an appropriate view. 3. Choose major parts, i.e. parts that have several parts assembled on. 4. Draw a view of major parts according to a selected viewing direction. STEPS TO CREATE ASSEMBLY DRAWING 5. Add detail view of the remaining parts at their working positions. 6. Apply section technique where relative positions between adjacent parts are needed to clarify. 7. Add balloons, notes and dimensions (if any). 8. Create BOM. GENERAL PRACTICE The number of views can be one, two, three or more as needed, but it should be minimum. A good viewing direction is that represents all (or most) of the parts assembled in their working position. EXAMPLE : Selection of a necessary view Given Part A Student A Part B Student B Which is an appropriate view for assembly drawing ? GENERAL PRACTICE Hidden lines usually omit unless they are absolutely necessary to illustrate some important feature that the reader might otherwise miss. EXAMPLE : Hidden lines omit or not ? A Part A B C Part B Good Poor EXAMPLE : Hidden lines omit or not ? A Part A B Part B Good Poor EXAMPLE : Hidden lines omit or not ? A Part A B Part B Good Poor GENERAL PRACTICE Section technique is usually need to clarify mating of the parts. Use different section line styles for adjacent parts. Correct Part A Better Part B Color OFF ON SECTION LINE PRACTICE Do not draw section lines on sectional view of standard parts. - Threaded fastener - Washer - (longitudinal cut of) Solid shaft, Pin, Key EXAMPLE 1 : Assembly steps 1 CLEVIS, Steel, 1 REQD. 2 ARM, Steel, 1 REQD. 3 PIN, Steel, 1 REQD. EXAMPLE : Section line practice A B Which is an appropriate full section view of this assembly ? Good Poor Color OFF ON EXAMPLE 2 : Assembly steps 1 SUPPORT, Steel, 1 REQD. 2 SHAFT, Steel, 1 REQD. 3 TAPER PIN, Steel, 1 REQD. EXAMPLE : Section line practice A Which is an appropriate full section view of this assembly ? Good Color Poor OFF ON B C D EXAMPLE 3 : Assembly steps 2 ARM, Steel, 1 REQD. 1 CLEVIS, Steel, 1 REQD. 3 PIN, Steel, 1 REQD. EXAMPLE : Section line practice A B C Which is an appropriate section view of the joint ? Good Poor Color OFF ON LEADER LINE PRACTICE Drawn from the inside of the part to the balloon and placed a filled circle at the beginning of a line. Drawn in the oblique direction. 1 2 EXAMPLE Shaft Bearing Cap screw Cover plate Housing Mating of Parts POINTS TO CONSIDER 1. Surface finishing 2. Tolerance - Size - Geometry SURFACE FINISHING Surface finishing means the quality of a surface. It relates to the level of roughness of a surface. Purpose 1. To control the accuracy in positioning and tightness between mating parts. 2. To reduce the friction, especially for the part moves relative to other parts. TOLERANCE Tolerance is the total amount dimension may vary. It is defined as the difference between the upper and lower limits. Purpose 1. To control an interchangeability of parts. 2. To ensures the mating part will have a desired fit. ...
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This note was uploaded on 02/02/2012 for the course DRAW 101 taught by Professor Laosimkim during the Spring '11 term at University of Macau.

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