© Pearson & GNU Su-Jin Kim Plastics Manufacturing Processes Plastics & FRP Associate Professor Su-Jin KimSu-Jin Kim School of Mechanical Engineering Gyeongsang National University

© Pearson & GNU Su-Jin Kim Plastics Manufacturing Processes Contents 1. Plastic Process Extrusion ( 압출 ) Injection molding ( 사출금형 ) Blow molding Thermo forming 2. Composite ( 복합재료 / 강화플라스틱 ) Composite process 3. Rapid prototyping ( 쾌속조형 )

© Pearson & GNU Su-Jin Kim Plastics Manufacturing Processes Processing of Plastics 1.Extrusion ( 압출 ) 2.Injection molding ( 사출 ) 3.Blow molding 4.Thermo forming

© Pearson & GNU Su-Jin Kim Plastics Manufacturing Processes Extrusion The molten plastic is forced through a die and cooled. Long products with constant cross-section are extruded. High production rates, low tooling cost. © 갈창우, GNU

© Pearson & GNU Su-Jin Kim Plastics Manufacturing Processes Injection molding Hopper Barrel Mold Plastics are melted in a heated cylinder and forced into a mold by hydraulic plunger of rotating screw. Complex shape and good dimensional accuracy can be achieved, as in die casting.

© Pearson & GNU Su-Jin Kim Plastics Manufacturing Processes Injection molding Die structure SLIDE CORE EJECTION PLATEEJECTION PINRETURN PIN GUARD BUSH GUARD PIN ROCKET RING SPRUE BUSHING ANGULAR PIN CORE 돌출판돌출핀 Injection Mold JY-Solutec

© Pearson & GNU Su-Jin Kim Plastics Manufacturing Processes Injection molding Vacuum Cleaner: Hand grip Blower: Housing

© Pearson & GNU Su-Jin Kim Plastics Manufacturing Processes Design for Injection Molding Parting line is flat or simple-curved surface Flow path ratio (length/thickness < 200) Clamping force = Pressure x Area Draft angle 1~2˚ Shrinkage PE(1.5~6), PP(1~3), PS(.2~.6), PVC(0.1~0.5) Reinforcements (ribs and bosses) Defects : Sink mark, Weld line, Air traps, Deflection

© Pearson & GNU Su-Jin Kim Plastics Manufacturing Processes Injection Molding MIT Lecture Node design-and-manufacturing-ii-spring-2004/lecture- notes/04_polymer_1_6_f.pdfhttp://ocw.mit.edu/courses/mechanical-engineering/ design-and-manufacturing-ii-spring-2004/lecture- notes/04_polymer_1_6_f.pdf design-and-manufacturing-ii-spring-2004/lecture- notes/05polymer_2_6f1.pdfhttp://ocw.mit.edu/courses/mechanical-engineering/ design-and-manufacturing-ii-spring-2004/lecture- notes/05polymer_2_6f1.pdf

© Pearson & GNU Su-Jin Kim Plastics Manufacturing Processes Blow molding Blow up a plastic balloon to fill the mold. Hollow thin-wall parts; beverage and food containers.

© Pearson & GNU Su-Jin Kim Plastics Manufacturing Processes Blown film A thin-walled tube is extruded and expanded into a balloon shape by blowing air until the desired film thickness is reached.

© Pearson & GNU Su-Jin Kim Plastics Manufacturing Processes Thermo (Vacuum) forming The thermoplastic sheet is heated by an oven until it is softened, pressed into the mold using vacuum pressure, and held until it cools. Medium production rates, low tooling cost.

© Pearson & GNU Su-Jin Kim Plastics Manufacturing Processes Economics of Processing Plastics Design and manufacturing decisions are based on costs of equipment, tooling and production volume Number of parts Machining Extrusion Injection molding Blow molding Thermo forming Production rate