6 Mold Design Different Kinds of Moulds PDF

20.11.2024 Different Kinds of Moulds 1 Task & Functions of a Mould Tasks: Function: Gating Transfer motion...

20.11.2024 Different Kinds of Moulds 1 Task & Functions of a Mould Tasks: Function: Gating Transfer motion Venting Absorb Forces / Tempering the mould Retain Shape (cooling/heating) Demoulding Guiding of mould  No undercut parts Moving half  Outer undercut Fixed half  Inner undercut Long lifetime Guide & centre Mould Design/WS 2024/2025. Michael Kaisser. Page: 2 20.11.2024 2 1  20.11.2024 Mould Standard Parts  Standard (Not unique items)  Tried, tested & reliably used for many years  Functional guarantee  Quickly available  Replaceable for repairs & modifications  Cheaper  CAD data available Source: Strack Normalien Mould Design/WS 2024/2025. Michael Kaisser. Page: 3 20.11.2024 3 Parts of a Injection Mould Part: Description: Mould Core 1. Moving half back Fits the moving platen (injection moulding machine) & provides the plate framework for the core or cavity to be mounted on. When open, part can be ejected 2. Bolts 3. Risers Provide Space for the ejector plate to move 4. Ejector Plate Create a small gap between fixed plate and ejector plate to prevent the Feet accumulation of dirt 5. Ejector locating Location plate guides the ejector pins to the correct place & the retainer plate & Retainer prevents the ejector pins from pushing back too far. The stability of the ejector plate is partially reinforced by bushes 6. Bolster sleeves Keeps all elements of the bolster together, square & aligned 7. Moving half Fits the moving part of injection moulding machine & provides support plate framework for the core or cavity to be mounted on. When opened: molded part can be ejected Moving Half 8. Guide Bushes Provide the bearing surface for the quide pins, protecting core plate from wear 9. Retaining Plate Core can be mounted on top or recessed into this Source: toolcraft plastics Mould Design/WS 2024/2025. Michael Kaisser. Page: 4 20.11.2024 4 2  20.11.2024 Parts of a Injection Mould Part: Description: 10. Mould Core & Shaped sections in either half of the mould tool which give the part the final 11. Mould Cavity shape. Hot material is injected into the core & cavity. Design of core & cavity is essential for formation of the product. Essential Elements are: Gate: Point between runner & cavity Runner: Allow the passage of molten plastic material to core & cavity. Runners can be hot & cold Temperature canals: for uniform or controlled heat distribution. Common are: (pressurized) water, oil or electric systems 13. Guide Pins Slide into the holes in the ohter half. Guides ensure the two halves of the mold are correctly aligned so the the product is correctly formed. 14. Cavity retaining pl. Core can be mounted on top or recessed into this. 15. Sprue bush Where plastic is injected from machine into cavity. Can be hot tip (less material, greater moulding flexibility) or cold tip (less costly). Fixed Half 16. Fixed half back Fits fixed platen of injection moulding machine and provides the framework plate for the core or cavity to be moulded on 17. Bolts 18. Location ring Ensure allignment beween fixed half platen & injection moulding machine Source: toolcraft plastics Mould Design/WS 2024/2025. Michael Kaisser. Page: 5 20.11.2024 5 Steels for Functional Pars/Standard Parts Application DIN EN 10027 Material Mechanical Properties Ejector Pins 115CrV3 1.2210 Cold work steel Hardened & strengthen: 60-63 HRC C110W2 1.1650 Unalloyed steel Hardened & strengthen: 60-63 HRC Guide Pins C110W1 1.1550 Unalloyed steel Hardened & strengthen: 55-62 HRC Boltster sleeves 16MnCr5 1.7131 Cold work steel Surface hardness: 60 HRC Back plate Ck 22 1.1151 Unalloyed steel Strengthen: 400-500N/mm² Ejector locating plate Ck 45 1.1191 Unalloyed steel Strengthen: 400-500N/mm² Retaining plates Ck 60 1.1221 Unalloyed steel Strengthen: 800-900N/mm² 55NiCrMoV 6 1.2713 Hot work steel Strengthen: 800-950N/mm² 21MnCr45 1.2162 Cold work steel Surface hardness: 60 HRC Locating Ring St 50 1.0530 Low carbon steel (soft steel) Strength: 500-600 N/mm² Sprue busing 14NiCr14 1.2735 Cold work steel Surface hardness: 60 HRC 56NiCrMoV7 1.2714 Hot work steel Soft annealed: 2500 HB Source: Menges/Mohren: Spritzgiesswerkzeuge Mould Design/WS 2024/2025. Michael Kaisser. Page: 6 20.11.2024 6 3  20.11.2024 Tolerances of Shafts and Bushes Guide Pin 690 + 70 HV 30 1.0401 1 Guide Pin 11.0401 or C15 is an unalloyed case-hardening steel Source: Hasco Strack: 1.7131 (60+2 HRC) → 16MnCr5 Mould Design/WS 2024/2025. Michael Kaisser. Page: 7 20.11.2024 7 Kinds of Injection Moulds Basic Mould  Easy design Fixed half Moving half  2 mould halves, one parting line  One opening direction  Demoulding by gravity & using ejector pins, sockets  (normaly) no undercut (except: forced demoulding) Centring Element 3xØ1 1xØ2 Mould Design/WS 2024/2025. Michael Kaisser. 20.11.2024 Page: 8 8 4  20.11.2024 Kinds of Injection Moulds Mould Design/WS 2024/2025. Michael Kaisser. 20.11.2024 Page: 9 9 Kinds of Injection Moulds Isolation Boards Source: Meusburger Georg GmbH / Wolfurt (A) Lifting unit Composits from resin bonded glass fibres and fillers: Application temperature: 210°C Source: LMK Präzisionswerkzeuge ( Coburg Thermal Conductivity: 0.18 W/mK Mould Design/WS 2024/2025. Michael Kaisser. 20.11.2024 Page: 10 10 5  20.11.2024 Kinds of Injection Moulds Slider Mould  Construction similar basic mould  At least 2 opening directions. Activated by mechanic force (slider) or core puller (hydraulic force) bolt wedge  Two opening direction  Flat parts, containing undercuts, breakthrough  Wedge area hardened & exchangable αb = αw - 2° αw = 15° to 30° Why αb = αw - 2° ? Mould Design/WS 2024/2025. Michael Kaisser. Page: 11 20.11.2024 11 Kinds of Injection Moulds Slider Mould - Principle Mould partly opened Main opening direction Moving Half Mould closed Additional opening direction Slider Slider Fixed Half Why are sliders normally on the moving half of a mould? Mould Design/WS 2024/2025. Michael Kaisser. Page: 12 20.11.2024 12 6  20.11.2024 Example Slide Mold: Undercuts  Undercuts can be moulded, but require a lateral pull or action as they are an additional part of the mold that moves independently of the two halves.  Undercuts can drive up the cost of the molded part by increasing the cost of the mold itself by 15-30%  Undercuts may increase the cycle time & increasing the complexity of the injection molding machine & maintanance  Instead of mechanical force, a hydraulic cylinder can be used to demould undercuts → large strokes or special movements Mould Design/WS 2024/2025. Michael Kaisser. Page: 13 20.11.2024 13 Kinds of Injection Moulds Core Puller In a core-puller mould, the moving parts are actuated hydraulically or pneumatically according to the run-on program. The individual positions are controlled by switch For bigger cores (“Fittinge”) or big lengths. The quality of the molded parts depends on the condition of the guides and closing surfaces: Maintenance and lubrication! Source: Nolden Mould Design/WS 2024/2025. Michael Kaisser. Page: 14 20.11.2024 14 7  20.11.2024 Kinds of Injection Moulds Split-Mould Splits  Construction similar to slider mould  For bigger parts with outer thread or undercusts  2 mould halves, one parting line  2 opening directions: vertical & horizontal  Demoulding by gravity & using ejector pins, sockets Source: Meusburger /Wolfurt (A) und LAMY Mould Design/WS 2024/2025. Michael Kaisser. Page: 15 20.11.2024 15 Kinds of Injection Moulds 3-Plate Mould  Complex shape  2 parting lines  Degating of multi gates  Operation by ratchet („Klinke“) or tension rod („Zuganker“)  Direct gating with cold runner & multiple cavities Mould Design/WS 2024/2025. Michael Kaisser. Page: 16 20.11.2024 16 8  20.11.2024 Kinds of Injection Moulds Principle of 3-Plate Mould Closed Position 2 Steps opening process 1. Steps opening 2. Steps opening To avoid deformation the ejector  Plate movement to break gate & pull sprue system can be stabilized by bushes  Main parting line gap must allow for the full stripper plate action & also for molded part to be ejected  Plate movement to strip the runner Mould Design/WS 2024/2025. Michael Kaisser. Page: 17 20.11.2024 17 Kinds of Injection Moulds 3-Plate Mould Video 7 Source: Strack Normalien / Lüdenscheid Mould Design/WS 2024/2025. Michael Kaisser. Page: 18 20.11.2024 18 9  20.11.2024 Kinds of Injection Moulds Screw-Mould  Stripper Plate Mould → Forced Demoulding → Unrotating  Stripper Plate Mould → Collapsing Core → Unrotating  Rack steering → Rotating Elements  Spindle – Thread Unscrewing Unit → Rotating Elements  Hydraulic force → Rotating Elements Mould Design/WS 2024/2025. Michael Kaisser. Page: 19 20.11.2024 19 Kinds of Injection Moulds Inner Thread – Forced demoulding  Forced demoulding limited solution  Depending on material → low E-Modulus Ø-ε Ø  Kind of thread  Common materials: PE, PP & PA Material Elongation [%]  Same design rules as for demoulding PA