© pearson & gnu su-jin kim plastics manufacturing processes plastics & frp associate...

© Pearson & GNU Su-Jin Kim© Pearson & GNU Su-Jin Kim

PlasticsPlasticsManufacturing ProcessesManufacturing Processes

Manufacturing ProcessesManufacturing Processes

Plastics & FRPPlastics & FRP

Associate Professor Su-Jin Kim

School of Mechanical EngineeringGyeongsang National University



Contents

1. Plastic Process• Extrusion ( 압출 )• Injection molding ( 사출금형 )• Blow molding• Thermo forming

2. Composite ( 복합재료 / 강화플라스틱 )• Composite process

3. Rapid prototyping ( 쾌속조형 )



Processing of Plastics

1. Extrusion ( 압출 )2. Injection molding ( 사출 )3. Blow molding4. Thermo forming



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.

http://kr.youtube.com/watch?v=Ct34UCjOr-c&feature=related

Throat

Barrel

Gear reducer Box

Thermocouples

Feed section

Barrel heater/cooler

Barrel liner

Melt thermocouple

Melt section

Adapter

Breaker plate

Melt-pumping section Screw

Die

Wire filter screen

Hopper

Motor

© 갈창우 , GNU



Injection molding

http://ma.gnu.ac.kr/vod/Plastic/Plastic_Injection.wmvhttp://ma.gnu.ac.kr/vod/Plastic/Plastic_Injection_Molding.MP4http://kr.youtube.com/watch?v=bit-D1NnfjI&NR=1http://kr.youtube.com/watch?v=NedTUB7YQE0&feature=related

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.



Injection molding

• Die structureSLIDE CORE

EJECTION PLATE EJECTION PIN RETURN PIN

GUARD BUSH

GUARD PIN

ROCKET RING

SPRUE BUSHINGANGULAR PIN

CORE

돌출판 돌출핀Injection Mold http://ma.gnu.ac.kr/vod/Plastic/Injection_Mold.wmvJY-Solutec http://www.jysolutec.com



Injection molding

Vacuum Cleaner: Hand grip

Blower: Housing

http://www.tsmould.com/cyberpr01.htm



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



Injection Molding

• MIT Lecture Node

• http://ocw.mit.edu/courses/mechanical-engineering/2-008-design-and-manufacturing-ii-spring-2004/lecture-notes/04_polymer_1_6_f.pdf

• http://ocw.mit.edu/courses/mechanical-engineering/2-008-design-and-manufacturing-ii-spring-2004/lecture-notes/05polymer_2_6f1.pdf



Blow molding

http://www.youtube.com/watch?v=vSabFFQUr9E&p=9B6D9EAE75875D9Dhttp://kr.youtube.com/watch?v=grIPNOHkdOc&feature=relatedhttp://kr.youtube.com/watch?v=3haIAsECzRchttp://www.youtube.com/watch?v=oR0gMKN58kY&p=9B6D9EAE75875D9D

• Blow up a plastic balloon to fill the mold.• Hollow thin-wall parts; beverage and food containers.



Blown film

• A thin-walled tube is extruded and expanded into a balloon shape by blowing air until the desired film thickness is reached.

http://kr.youtube.com/watch?v=W0QbPtYXsRs&NR=1



Thermo (Vacuum) forming

http://kr.youtube.com/watch?v=deeENCiuKWMhttp://kr.youtube.com/watch?v=YCGEKT3iHMs&feature=relatedhttp://www.metacafe.com/watch/1685267/thermoforming_machine_by_europack1_gmail_com/

• 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.



Economics of Processing Plastics

• Design and manufacturing decisions are based on costs of equipment, tooling and production volume.

10 102 103 104 105 106 107 Number of parts

Machining

Extrusion

Injection molding

Blow molding

Thermo forming

Pro

duc

tion

rate

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