Manufacturing Processes Plastics & FRP Professor Su-Jin Kim Mechanical Engineering Gyeongsang National University 1

Contents 1. Plastic Process Injection molding (사출금형) Blow molding Thermo forming Extrusion (압출) 2. Composite (복합재료/강화플라스틱) Composite process 3. Rapid prototyping (쾌속조형)

Processing of Plastics Injection molding (사출) Blow molding Thermo forming Extrusion (압출)

Plastic Injection molding Molten plastic is injected into a mold by hydraulic plunger Good dimensional accuracy as die-casting Hopper Mold Barrel Plastic injection molding: https://youtu.be/RMjtmsr3CqA

Injection mold Mold structure Sprue busing Guard busing Ejection pin Injection Mold http://ma.gnu.ac.kr/vod/Plastic/Injection_Mold.wmv JY-Solutec http://www.jysolutec.com

Injection Mold

Flow analysis MAPS-3D Plastic injection process analysis VMTech: http://www.wincapa.com

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

Blow molding Blow up a plastic balloon to fill the mold. Hollow thin-wall parts; beverage and food containers. http://kr.youtube.com/watch?v=grIPNOHkdOc&feature=related http://kr.youtube.com/watch?v=3haIAsECzRc http://www.youtube.com/watch?v=oR0gMKN58kY&p=9B6D9EAE75875D9D

Thermo (Vacuum) forming The thermoplastic sheet is heated, pressed into the mold using vacuum pressure Medium production rates, low tooling cost Vacuum http://kr.youtube.com/watch?v=deeENCiuKWM http://kr.youtube.com/watch?v=YCGEKT3iHMs&feature=related

Plastic Extrusion The molten plastic is forced through a die and cooled. Long products with constant cross-section High production rates, low tooling cost Throat Barrel Gear reducer Box Thermocouples Feed section Barrel heater/cooler liner Melt thermocouple Melt section Adapter Breaker plate Melt-pumping section Screw Die Wire filter screen Hopper Motor ©갈창우, GNU https://youtu.be/Tp2Rdx69SSo

Blown Film Extrusion A thin-walled tube is extruded and expanded into a balloon shape by blowing air until the desired film thickness is reached. https://youtu.be/WLyaZbT97EI https://youtu.be/W6V0w-ajtN8

Economics of Processing Plastics Design and manufacturing decisions are based on costs of equipment, tooling and production volume. Extrusion Injection molding Blow molding Production rate Thermo forming Machining 10 102 103 104 105 106 107 Number of parts

Reference Wook-Ryol Hwang, GNU : http://rmp.gnu.ac.kr Plastic injection molding process analysis, VM Tech: http://wincapa.com Mold: http://asis.co.kr Mold: http://www.naramnd.com Mold http://www.tsmould.com Injection machine : http://dongshin.net Plastic : http://lgchem.com

Fiber Reinforced Polymer, FRP (Composites) FRP (복합재료) Fiber(섬유) + Plastic matrix (모재) Fiber: Kevlar, Glass fiber, Graphite fiber, Boron Plastic matrix: Epoxy, Polyester Process Impregnation: fiber+resin Molding Compression molding Vacuum bag molding Open molding Resin transfer molding http://vimeo.com/13769356

Molding Reinforced Plastics Prepreg & Autoclave Vacuum bag molding Open molding (Contact molding) Resin transfer molding (RTM) Filament winding

Prepreg Prepreg is a term for "pre-impregnated" composite fibers containing polymer matrix. The pre-preg are mostly stored in cooled areas since activation is most commonly done by heat.

Vacuum-bag molding Prepregs lay in mold and apply pressure in a vacuum. Atmospheric pressure Clamping bar Vaccum trap Gel coat Gasket Vacuum trap Flexible bag Room temperature or oven cure hand or spray lay-up Mold release Resin and glass Mold ©갈창우, GNU

Autoclave Hence, composite structures built of pre-pregs will mostly require an oven or autoclave to cure out. Temperature 180 °C, Pressure 600kPa, Time 3 h

Sheet molding compound (SMC) & Compression Molding Compression molding: SMC is placed between two molds and pressure is applied. Compression Molded Composite Sheet molding compound

Open-molding Open-molding process use single male or female mold and also called contact-molding Used in making products with high surface-area-to-thickness ratios. Hand lay-up Spray lay-up http://ma.gnu.ac.kr/vod/Plastic/FRP_Boat.MP4

Resin Transfer Molding (RTM) Resin Transfer Molding (RTM) allows the molding of components with complex shapes and large surface areas with a good surface finish on both sides. http://www.youtube.com/watch?v=1u-2GvhghQA

Filament winding Glass fibers are embedded in thermosetting resin matrix materials and winded around a pipe. FRP pipe CNG tank

Composite Machining & Joining

Rapid prototyping 3d CAD  Real part

Rapid prototyping Making a physical prototype directly from 3D CAD drawing. CAD solid model Translation to STL format Slice the model into layers Send data to RP machine Curing each layer by laser

Rapid Prototyping Usage

Rapid Prototyping Usage

3D Printing Roller spreads powder Inkjet traces the shape of each section http://ma.gnu.ac.kr/vod/Plastic/3d_printer.MP4 http://ma.gnu.ac.kr/vod/Plastic/3d_pirinter_objet.mpeg

SLA (Stereo Lithography Apparatus) Vat filled with photo-curable liquid resin Laser beam solidifies liquid resin of 2d cross-section Elevator drops enough to cover the solid polymer with another layer of liquid Cured Resin XY Scanning UV Laser Beam Photo-curable Resin (Liquid) Top of the Liquid Elevator Vat

SLS (Selective Laser Sintering) Roller spreads powder across the top of the elevator Laser traces the shape of each cross-section, fusing powder in the thin layer

FDM (Fused Deposition Manufacturing) Dispenser heats the plastic and extrudes it at the desired position. Deposited plastic solidifies to form a hardened layer.

Reference Polymer Mixing (W. R. Whang) : http://rmp.gnu.ac.kr/ Mechanical Properties of Composite (J. H. Choei): http://gsnu.ac.kr/hb/11176/

Injection molding insert label in pet mold

Multiple injection molding (복합사출) Product with hard and soft plastics. Sliding split mold S778T + TPE Turn table mold