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Unformatted text preview: MIT OpenCourseWare http://ocw.mit.edu 2.007 Design and Manufacturing I
Design Released For production Mfg docs produced: purchase specs, assy instructions, design drawings for tool/fixtures, instruction manuals, etc. Hard tooling produced: dies, molds, fixtures, etc. Manufacturing, Assembly, Testing Design Ramifications: Early decisions have large leverage Late changes are very costly Time Motivation
Computer-based models permit designers to better understand how their products will look and function before physical models are made
Make better early decisions Eliminate late changes (Enables you to work on your machine even when the shop is closed...) History of New CAD/CAM Functionality 1960's - Design of complex surfaces, programming of NC machine tools 1970's - Automation of Drawings 1980's Solids 1990's - Parametric Feature-based Solids Key Concept
Changes in dimensions propagate between parts, drawings, assemblies Movie Philosophy of CAD Lectures
Demonstrate small fraction of available functionality
Ideally the most useful fraction... Accelerate your learning process
Get you up-to-speed as quickly as possible... Promote self-discovery
Motivate you to learn more on your own... Demonstrate use as a design tool
Not (just) a detailing/documentation tool Reminder
To those who have "seen it before":
bear with us help those who haven't Features
2D geometry (sketch) swept along a 3D path Applied
Attached to existing geometry Sketched Feature Types
Constant cross-section along a straight line Revolve
Constant cross-section around an axis of revolution Sweep
Constant cross-section along a space curve Loft
Multiple cross-sections along a space curve Sketched Features
May add or subtract material !
Extrude Revolve Sweep Loft (add) boss/base boss/base boss/base boss/base (subtract) cut Hole Wizard cut cut Require cut more
complex mfg methods Applied Features
Attached to existing geometry
e.g. edges, faces Types
Fillet Pattern Shell Draft Rib Injection-molded parts The Drill... Drill...
Series of demonstrations/exercises
Demonstration: You watch it done Exercise: You do it Demonstrations / Exercises
Screen/window layout View control Make a simple part Dimensions & sketch relations Linkages & Blocks Symmetry Make a simple part Dimensions & Sketch Relations Linkages & Blocks Symmetry Case Study Ramp
Drop-down ramp (see geometry) Companion robot drives onto ramp Companion robot (150 lb)
is lifted off the ground Powered by pneumatic cylinder(s) Geometry
Virtual Work Principle: F1 dx1 = F2 dx2 dx2 F2 F1 dx1 END ...
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- Spring '11