me_350_-_lect_19_-_dfa.20091104.4af252924c1257.72561375

me_350_-_lect_19_-_dfa.20091104.4af252924c1257.72561375 -...

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Design for Assembly: 1. By knowing part information and manufacturing method – DFA programs can quantify: 1. Assembly Time 1. Manufacturing cost 2. The purpose of DFA programs are to provide a guidance and methodology to: Optimize Assembly Assembly typically occupies between 40% and 60% of the total production period (manufacture time). ME 350 – Lecture 19 – DFA
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Assembly Software Assembly software programs are based upon years of industrial data to accurately determine: 1. Handling Time 1. Insertion Time 2. Securing (or fastening) Time Software can propose alternative designs and which parts are candidates for elimination or simplification
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Handling time depends upon: Grasping method (tweezers, tool, one hand, two hands, two person, etc.) Presentation (fetching distance, entanglement potential if in a bin with similar parts, conveyor, automated dispense, tray, slide feeder, etc.) Size (smaller parts take longer, and large parts take longer than “medium” or “ideal” sized parts) Part symmetry, if rotation or orientation is needed for alignment
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Insertion time depends upon: Part alignment or tolerance Part size Insertion symmetry (α and β symmetry) Insertion force, access, depth, etc. Secure time depends upon method: Thread, bolt, or screw (hand or machine) Snap, Rivet (solid, tubular, blind, two part) Press fit, Self-stick Crimp, etc.
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Example problem Can we determine and compare the assembly time for these parts? First we need to learn terminology and make assumptions
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α symmetry: rotational symmetry about an axis perpendicular to the axis of insertion α = 180° DFA Part Symmetry - α α = 360° α (cube) = 90 α (rectangle) = 180
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β symmetry: rotational symmetry about the axis of insertion DFA Part Symmetry - β β = 0° β = 180° β = 60
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: length of the longest side of the smallest rectangular prism that can enclose the part. Aspect ratio
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This note was uploaded on 01/15/2010 for the course ME 350 taught by Professor Staff during the Spring '08 term at University of Illinois, Urbana Champaign.

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