Presentation on theme: "OBJECTIVES VARIOUS MOLDING TECHNIQUES FOR DIFFERENT TYPES OF COMPONENTSABOUT INJECTION MOLDING MACHINE.ABOUT MOLDFEEDING SYSTEMMOLD FLOW ANALYSISUNDERCUT."— Presentation transcript:
OBJECTIVES VARIOUS MOLDING TECHNIQUES FOR DIFFERENT TYPES OF COMPONENTSABOUT INJECTION MOLDING MACHINE.ABOUT MOLDFEEDING SYSTEMMOLD FLOW ANALYSISUNDERCUT AND REMOVAL PROCIDUREPLASTIC PRODUCT DESIGNCOMMON DEFECTS IN PLASTICS PARTS
VARIOUS MOLDING TECHNIQUES FOR DIFFERENT TYPES OF COMPONENTS.
ABOUT INJECTION MOLDING MACHINE.
MAJOR PARTS OF MOLDING MACHINE Injection UnitClamping& Ejection Unit
DETAIL PARTS OF INJECTION MOLDING MACHINE & THEIR FUNCTION
TYPES OF MOLD BASED ON FEEDING SYSTEM COLD RUNNER MOLD HOT SPRUE MOLD HOT RUNNER MOLD BASED MOLD OPENING 2 PLATE MOLD 3 PLATE MOLD BASED ON TYPE OF COMPONENT SINGEL PART MOLD FAMILY MOLD BASED ON NUMBER OF PARTS SINGLE CAVITY MOLD MULTY CAVITY MOLD BASED ON SPECALITY COINJECTION MOLD INSERT MOLD
DISADVANTAGE 1) MORE COSTLY 2) SLOWER PRODUCTION RATE 3) MOLD HEIGHT WILL BE MORE ADVANTAGE 1) MOLD SIZE WILL BE LESSER AS THE FEEDING SYSTEM WILL BE ON UPPER PLATE 2) AUTO DEGATING POSSIBLE FIRST OPENING SECOND OPENING 2 PLATE MOLD 3 PLATE MOLD SINGLE OPENING BASED ON MOLD OPENING ADVANTAGE 1)MOLD WILL BE SIMPLE & CHEAP 2) VARIOUS TYPE OF GATES CAN BE ADOPTED. DISADVANTAGE 1)MOLD WIDTH AND LENGTH WILL BE MORE THAN 3 PLATE MOLD 2) AUTO DEGATING WILL BE POSSIBLE ONLY IN SUBMARRINE GATE
BASED ON FEEDING SYSTEM HOT SPRUE MOLD Hot Runner Benefits Faster Cycles % Faster Eliminates Material Waste - No Sprue or Runners(IN HOT RUNNER SYSTEM) Improves Part Quality - Less Stress - Better Appearance HOT RUNNER MOLD
MOLD PARTS TOP PLATE CAVITY PLATE CORE PLATE SPRUE BUSH CORE BACK PLATE RETURN PIN GUIDE BUSH SPACER BLOCK BOTTOM PLATE GUIDE PIN SLIDER ASSLY GUIDE BUSH` EJECTOR GUIDE PIN COMPONENT
SPRUE -It is the connecting path between machine nozzle & runner system. RUNNER -It is the connecting path between sprue & gate. GATE -It is the connecting path between runner and component.
SPRUE Sprue is the beginning of the melt delivery system within the mold The interface between the nozzle & the mold Taper shape has been made for avoiding the back flow of material.
REVERSE TAPER BEST Z PULLER GOOD GROOVE TROUBLE- SOME SPRUE PULLER
RUNNER SYSTEM A runner system that has been designed correctly will: Achieve the optimal number of cavities Deliver melt to the cavities Balance filling of multiple cavities Balance filling of multi-gate cavities Minimize scrap Eject easily Maximize efficiency in energy consumption Control the filling/packing/cycle time.
RUNNER BALANCING -FOR UNIFORM FILLING OF COMPONENT -FOR MAINTAINING UNIFORM PRESSURE INSIDE MOLD -REDUCE FILLING TIME AA AA B BB B UNBALANCED RUNNER SYSTEM BALANCED RUNNER SYSTEM (CHANGING RUNNER DIA) A A A AA AAA BALANCED RUNNER SYSTEM (CHANGING RUNNER LAYOUT)
Flow Direction Cold SlugWell COLD SLUG WELL -Plastic looses its temp during flow through runner. -Cold slug well is provided to accommodate the initial cold material and release behind hot material into cavity.
GATING Direct (sprue) gate Tab gate Edge (standard) gate Disc/Diaphragm gate Spoke gate Fan gate Film(Flash) gate Ring gate Manually Trimmed Auto-Ejection Trimmed Pin gate Submarine (tunnel, chisel) gate Hot-runner (hot-probe) gate Valve gate * The shape of gate will be decided based no the shape & appearance requirement of component.
DIRECT SPRUE GATE Molded Part Sprue Suitable for single cavity large components.
Single Tab GateMultiple Tab Gate Gate Tab Sprue 6 in. Max 12 in. Max Tab Sprue Gate Tab TAB/OVERLAP GATE Suitable for stress free and high optical clarity components.
Land Length Inches Maximum EDGE GATE Most commonly used.
Runner Part Runner Sprue DISC/DIAPHARGM GATE
PART RUNNER GATE LAND FAN GATE RUNNER Suitable for larger area with thin wall components.
Runner Parallel Runner Gate Parallel Runner FILM /FLASH GATE Suitable for thin walled flat comopnents. Used for the components required with stress and warpage free. Used for transparent components where flow mark is not allowed.
Gate Part Runner Disk Gate RING GATE
0.020 Land Length PIN POINT GATE
Molded Part Sprue Parting Line Tunnel Gate Zero Land Length Knock Out Pin Grind Flat on Gate Side, Min. 2 0 Fasten Pin Head To Prevent Turning SUBMARRINE GATE
R R Gate SUBMARRINE GATE
MOLD FLOW ANALYSIS
UNDERCUT AND REMOVAL PROCIDURE
UNDERCUTS ARE THE SHAPES -WHOSE ORIENTATION ARE NOT ALLONG WITH MODLING DIRECTION OF THE ENTIRE PART -LOCATION OF THESE SHPAES WILL BE BELOW PARTING LINE. TYPES OF UNDERCUT INTERNAL UNDERCUT EXTERNAL UNDERCUT
INTERNAL THREAD SNAP LID TYPES OF UNDERCUT INTERNAL UNDERCUT It can be removed by Force ejection Use of collapsible core Use of lifters Use of unscrewing mechanism(for threads)
Detail on SideExternal Thread TYPES OF UNDERCUT EXTERNAL UNDERCUT It can be removed by Side core actuated by mechanical pins, Hydrolic &Phumatic cylinders
TECHNIQUES FOR UNDERCUT REMOVAL CORE CAVITY MATCHING AREA FOR HOLE CORE CAVITY MATCHING
Plastic Core Pin Cored Hole Core Hydraulic Cylinder Cavity MOLDING DIRECTION SIDE CORE MOVEMENT BY HYDRAULIC CYLINDER
PLASTIC PRODUCT DESIGN
The first requirement is to have a properly modeled part that is fully moldable Sufficiently drafted faces to easily eject the part. No undercuts (will require lifters or sliders)lifterssliders Wall thickness should be uniform(if changing then it has to be gradually for avoiding shrink mark) When creating internal ribs, they should be no greater than 1/3t of the part’s wall thickness to avoid sink marks on the outside of the part. Drafted faces No draft = difficult to eject BASIC DESIGN CONSIDERATIONS
COMMON DEFECTS IN PLASTICS PARTS
Short Shot Flash Weld Lines Ejector Pin Marks Sink Marks
Short Shot Short defect Cold material, cold mold, insufficient pressure, non uniform mold temperature, insufficient feed, entrapped air, insufficient external lubrication, insufficient plunger forward time, small gates.
Flash Part w/ Moderate-Heavy Flash Flash Material too hot, Inj Pressure too high, High packing pressure, Less clamping force, Poor parting lines or mating surfaces
Weld Lines Weld lines is the meeting face of 2 flows coming in opposite direction. Part is weak at Weld line. Unavoidable areas Can result from poor gate placement Weld lines occurs if material temperature is low, mold temperature will be improper, improper gate position, improper runner balancing. Gate Weld Line Weld Line
1) Pin above flush 2) Pin below flush 3) Clearance around pin Marks are often left on the part in the area where the ejector pins pushed. Four possible cause: 4) Improper cooling time 5) Ejection force more. 6) Part sticking. Ejector Pin Marks
Sink Marks Improved Design Thick sections cause sink marks Sink mark occurs due to abrupt change of thickness. Thickness to be considered for every shape(Rib, Boss, Clip mountings) Minor sink marks can be removed by texturing Bad Design
Sink due to ribs Result after redesigning the Internal Ribs to be 1/3t or less of the nominal wall thickness Sink mark removed by optimizing the rib thickness to 1/3 t.