Unit 16 Engineering Drawing

Engineering Drawing Objectives Interpret different assembly drawings. Aims Introduce assembly drawing practices. Objectives Interpret different assembly drawings.

DEFINITION Working drawing Detail drawing Assembly drawing 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 1. completed shape of the product. 2. overall dimensions. 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.

TYPES OF ASSEMBLY DRAWING 1. Exploded assembly drawings The parts are separately displayed, 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.

Pictorial representation EXPLODED ASSEMBLY Pictorial representation Finished product

2. GENERAL ASSEMBLY Pictorial Orthographic

3. DETAILED ASSEMBLY

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 is 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.

EXAMPLE 1 : Assembly steps 3 PIN, Steel, 1 REQD. 2 ARM, Steel, 1 REQD. 1 CLEVIS, Steel, 1 REQD.

Parts List Item No. Description Qty Material Remarks 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: Item No. Description Qty Material Remarks

Item Number A table of parts Or BOM Leader lines

REQUIRED INFORMATION IN GENERAL ASSEMBLY DRAWING 1. All parts, drawn in their operating position. 2. Part list (or bill of materials, BOM) Item number Descriptive name Material, MATL. 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.

EXAMPLE : Hidden lines omit or not ? Part A Part B A B

GENERAL PRACTICE Section technique is usually need to clarify mating of the parts. Use different section line styles for adjacent parts. Part A Part B Correct Better

Task- draw these components individually and then assembled. Supply your own dimensions. 3 PIN, Steel, 1 REQD. 2 ARM, Steel, 1 REQD. 1 CLEVIS, Steel, 1 REQD.