INJECTION MOLD DESIGN PDT 317 PREPARED BY: EN. SHAYFULL ZAMREE BIN ABD RAHIM Email: shayfull@unimap.edu.my (019-4728377) shayfull@unimap.edu.my

COURSE CONTENT & COURSE OUTCOMES PDT 317 - INJECTION MOLD DESIGN COURSE CONTENT & COURSE OUTCOMES Study Week Course Content 1 – 2 CHAPTER 1: Introduction to Plastic Technology DEFINE and EXPLAIN the basic terminology process flow in plastic injection molding; EXPLAIN the differentiate type of mould, EXPLAIN, REVIEW and REPEAT the detail about injection molding machine. CO1: Ability to “define” and “describe” basic terminology process in plastic injection molding and mould design.

INJECTION MOLDING PROCESS PDT 317 - INJECTION MOLD DESIGN INJECTION MOLDING PROCESS What is Injection Molding Process??? A process that utilizes melted plastics injected into steel or aluminum molds which ultimately result in finished production parts. Method of forming a plastic to the desired shape by forcing the heat softened plastic into a relatively cool cavity under pressure. Manufacturing process where plastic is forced into a mold cavity under pressure.

PDT 317 - INJECTION MOLD DESIGN PLASTIC POLYMERS The word “polymer” is a combination of the Greek words: “poly" which means "many“ and “mer” which means “part” The basic structure of a polymer molecule can be visualized as a long chain of repeating units

Polymers’ Classification PDT 317 - INJECTION MOLD DESIGN Polymers’ Classification Thermoplastics: The word “thermoplastic” is a combination of the Greek words: “therm" which means “heat“ and “plastikos ” which means “capable of being molded” Once the polymer is formed it can be heated and reformed over and over again (allows recycling) Thermosets The word “thermoset” is a combination of the Greek words: “therm" which means “heat“ and “sets” irreversibly when heated Therefore, can not be remelted. Once these polymers are formed, reheating will cause the material to degrade

PDT 317 - INJECTION MOLD DESIGN PLASTIC MATERIALS

PDT 317 - INJECTION MOLD DESIGN PLASTIC MATERIALS

INJECTION MOLDING MACHINE PDT 317 - INJECTION MOLD DESIGN INJECTION MOLDING MACHINE

INJECTION MOLDING PRODUCTS PDT 317 - INJECTION MOLD DESIGN INJECTION MOLDING PRODUCTS

INJECTION MOLDING MACHINE PDT 317 - INJECTION MOLD DESIGN INJECTION MOLDING MACHINE The pellets are fed into heated cylinder and the melt is forced into the mold by hydraulic plunger or rotating screw of an extruder. Barrels are heated externally to promote melting of the polymer. The reciprocating screw will move backwards under pressure to a determined distance. The movement controls the volume of materials to be injected. The screw stops rotating and is pushed forward hydraulically forcing the plastic mold into the mold cavity.

INJECTION MOLDING MACHINE PDT 317 - INJECTION MOLD DESIGN INJECTION MOLDING MACHINE (a) (b) Injection Molding with (a) Plunger and (b) reciprocating screw

INJECTION MOLDING MACHINE PDT 317 - INJECTION MOLD DESIGN INJECTION MOLDING MACHINE Injection Pressure Injection Time Injection Speed Cooling Time Mold Temperature Barrel Temperature

PDT 317 - INJECTION MOLD DESIGN VIDEO : FUNDAMENTAL INJECTION MOLDING

PDT 317 - INJECTION MOLD DESIGN TYPE OF MOULDS Cold-runner, two-plate molds Cold-runner, three plate molds Hot-runner molds Multicomponent (Family Mold) Insert molding Overmolding 2 - Plates Mold 3-Plates Mold

PDT 317 - INJECTION MOLD DESIGN TYPE OF MOULDS Advantages of Two-Plate Molds Low fabrication cost Simple mold/tooling design Easy to setting injection molding machine parameter during molding Easy to maintenance the mold Short lead time for mold fabrication Easy to fitting and assembly the mold Simple ejection system of mold 2 - Plates Mold Disadvantages of Two-Plate Molds Runner and part not automatically separated (need secondary process to cut) The gate area can be seen clearly after cut

PDT 317 - INJECTION MOLD DESIGN TYPE OF MOULDS Advantages of Three-Plate Molds The runner automatic separated from the part during mold opening. The part cycle time can be reduced. (no need to cut the gate). Reduce production cost. Disadvantages of Three-Plate Molds The mold/tooling structures are complex. High cost of tooling fabrication. High maintenance cost of mold. Lead time for mold fabrication is long. 3-Plates Mold

PDT 317 - INJECTION MOLD DESIGN Phases of Moulding Filling Volumetrically fill the cavity Pressurization Build up pressure in the cavity Packing Add extra material to reduce shrinkage Pressurization Phase Filling Phase Packing Phase

GATING/DELIVERY SYSTEM PDT 317 - INJECTION MOLD DESIGN GATING/DELIVERY SYSTEM Sprue Polymer Entrance Point Primary Runner Part Cavity Gate Secondary Runner Cold Slug Well

PDT 317 - INJECTION MOLD DESIGN MOULDING STAGES Hopper Barrel Screw Mold Filling Mold closes Screw forward Frozen polymer skin forms at mold walls Packing Time Cavity filled Pressure applied to polymer Cooling occurs Gate freezes Screw is applying a specified pressure to the polymer melt in order to pack more plastic into the cavity.

MOULDING STAGES (Cont…) PDT 317 - INJECTION MOLD DESIGN MOULDING STAGES (Cont…) Cooling Part continues to cool until rigid enough to withstand ejection Screw moves back plasticizing resin for next shot Mold Open Part is ejected shayfull@unimap.edu.my

PDT 317 - INJECTION MOLD DESIGN MOULDING CYCLE TIME Cycle Time: Fill Time: Pack Time: Cooling Time: Mold Open Time: 22 Sec. 1 9 10 2

Defect and Causes in Injection Molding PDT 317 - INJECTION MOLD DESIGN Defect and Causes in Injection Molding Defect Causes Flashing Injection Pressure too high Clamping force to low Mold fitting not good Warping Non-uniform cooling rate Bubble To much moisture in material Shot Mold Air trap Injection Pressure not enough Sink Mark Injection Pressure too low Ejector Pin Mark Cooling time too short Ejection force too high

PDT 317 - INJECTION MOLD DESIGN Q&A

PDT 317 - INJECTION MOLD DESIGN SEKIAN TERIMA KASIH