21 polymer - ME250 Design and Manufacturing I Polymers...

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Polymers shaping processes ME250 Design and Manufacturing I
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2 Introduction Injection molding Blow molding Rotational molding Thermoforming Product design considerations Summary Outline
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3 Polymer processing process Heat to molten state to form in molds, cool (or cure at high temp.) to solidify. Involves large equipments: Economical only for high production volume. Introduction
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4 Injection molding process Pressurized molten plastic injected into a closed mold Open shape, sometimes with complex features Injection molding
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5 Injection-mold products Injection molding
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6 Injection-mold products Injection molding
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7 Injection molding machine Injection molding Injection unit Clamping unit
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8 Typical molding cycle Injection molding Mold is closed Melt is injected into cavity Screw is retracted Mold opens & Part is ejected http://www.youtube.com/watch?v=1-WjM0it9jI&NR=1 http://www.youtube.com/watch?v=349lszWKfZY&feature=related
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9 Two-plate mold Injection molding cavity plate core plate
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10 Injection mold Cavity plate Cavity (external part shape) runners gates side-pins (for under-cuts) Core plate core (internal part shape) core lifters (for under-cuts) Injection molding
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11 Undercuts complicates mold increased tooling/running cost increased cycle time Injection molding
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12 Angle-pin side- action molds Injection molding Unscrewing molds
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13 Three-plate mold Injection molding
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14 Other types of injection units Injection molding
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15 Other types of clamping units Injection molding
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16 Shrinkage allowances Dimensions of mold cavity must be larger than specified part dimensions: D c = D p + D p S + D p S 2 where:
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21 polymer - ME250 Design and Manufacturing I Polymers...

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