Injection moulding ppt

Injection moulding is a manufacturing technique for making parts from both thermoplastic and thermosetting. Plastic material in production molten plastic is injected at high pressure into a mould.

1. Seminar on : INJECTION MOULDING BY:-KUNDAN KUMAR (Department of Mechanical Engg.) Camellia Institute of Technology & Management

2. Historical Background In 1868 john wesley hyatt become the first to inject hot celluloid in to a mould, producing billiard balls. He and his brother patented an injection moulding machine that used a plunger in 1872, this process is work until 1946. In 1946 James Hendry built the first screw injection moulding machine .

3. Injection Moulding process – over view Solid wide neck, flat product is made like bucket, cabinets, Automobile & Industrial parts etc.. By injecting molten thermoplastic material into a closed mould which is relatively cool . Type of Injection Moulding Machine Hand Injection Moulding M/C Plunger Type Injection Moulding M/C Reciprocating Screw Type Injection Moulding M/C

4. Hand Injection Moulding Machine Vertical machine consist of Barallel , Plunger, Band Heaters along with energy regulator, Rack & Pinion system for injecting the material by the plunger, a torpedo and nozzle.

5. Plunger Type Injection Moulding machine Vertical and Horizontal plunger type injection moulding machine:

6. Reciprocating Screw Type Injection Moulding Machine The feeding zone The compressing (or transition) zone The metering zone

7. Components of reciprocating screw moulding machine

8. The injection process Plasticises the material by reciprocating screw. Injects the molten material to a closed mould -via a channel system of gates and runners. Cools the Mould. Refill the material for the next cycle Eject the product. Closes the mould for further cycle.

9. Different parts of mould in injection moulding machine.

10. Blow Moulding process and mould

11. Screw Used in Injection Moulding machine The screw has three zones with a ring-plunger assembly. The Feed Zone. Where the plastic first enters the screw and is conveyed along a constant compressed and melted along a root diameter; the Transition zone , where the plastic is conveyed, compressed and melted along the root diameter that increases with a constant taper; and the Metering Zone . Where the meting of the plastic is completed and the melt is conveyed forward along a constant root diameter reaching a temperature and viscosity to form parts.

12. L/D Ratio The L/D ratio is the ratio of the flighted length (Effective Length) of the outside diameter. Most injection screws use a 20:1 L/D ratio. But it may range from 18:1 to 24:1 In the case of Thermoplastic it may range from 12:1 to 16:1 Compression Ratio (CR) The ratio of the first flight depth of feed zone to the last flight depth of meter zone. Or, First channel Volume of feed zone to last channel volume of metering zone. Typically ranges from 1.5:1 to 4.5:1 for most thermoplastic materials. Most Injection screws classified as general purpose have a compression ratio of 2.5:1 to 3:1. Thermo set screws have a 1:1 ratio.

13. Back pressure(Kg/ Cm 2 or bar ) Back pressure is the amount of pressure exerted by the material ahead of the screw, as the screw is pushed back in preparation for the next shot. Injection speed (Cm/Sec ) The injection speed is the forward speed of the screw during its injection operation per unit time. Screw Rotation Speed The screw rotation speed (RPM) is the rate at which the plasticizing screw rotates.

14. Cushion The cushion is the difference in the final forward position of the screw and its maximum allowable forward position. More cushion results more residence time, some time degrades. If the screw were allowed to travel its full stroke and stop mechanically against the nozzle, the cushion would be zero. With zero cushion no hold on works. Typically a cushion of 3 to 6mm is used.

15. Injection Moulded Items

16. Advantages of Injection Moulding process Parts can be produced at high production rates. Large volume production is possible. Relatively low labour cost per unit is obtainable. Process is highly susceptible to automation. Parts require little or no finishing. Many different surfaces, colours, and finishes are available. Good decoration is possible. For many shapes this process is the most economical way to fabricate. Process permits the manufacture of very small parts which are almost impossible to fabricate in quantities by other methods. Minimal scrap loss result as runners, gates and rejects can be reground and reused.

17. Limitations of Injection Moulding Intense industry competition often results in low profit margins. Mould costs are high. Moulding machinery and auxiliary equipment costs are high. Lack of Knowledge about the fundamentals of the process causes problems. Lack of knowledge about the long term properties of the materials may result in long-term failures. Materials for Injection Moulding 1. Acetal 8. Polyphenylene oxide 2. Acrylic 9. Poly phenylene 3. Polycarbonate (pc) 10. Polystyrene 4. Polyester 11. Polysulphone 5. Polyethylene 12. Polyvinyl chloride(PVC) 6. Fluoro plastic 13. Acrylonitrile butadiene styrene 7. Polyimide 14. Nylon

18. CLAMPING Types of clamping.:- TOGGLE TYPE CLAMPING 2 . HYDRAULIC CLAMPING 3. TIE-BAR LESS CLAMPING

19. Setting Machine Process conditions Set the melt temperature Set the mould temperature Set the switch-over position Set the screw rotation speed Set the back pressure Set the injection pressure to the machine maximum. Set the holding pressure at 0 Mpa Set the injection velocity to the machine maximum Set the holding time Set ample remaining cooling time Set mould open time Mould a short-shot series by increasing injection volume Switch to automatic operation Set the mould opening stroke Set the ejector stroke, start position and velocity Set the injection volume to 99% mould filled increase the holding pressure and minimize the holding time Minimize the remaining cooling time

20. Temperature History in an Injection Moulded part Pressure History in an Injection Moulded part

21. Cycle Time In Injection Moulding

22. Post Moulding Operation Chrome Plating In Mould Insert Moulding Post Mould Inserting Drilling Polishing 6. Heat inserting 7. Assembly

23. Secondary Operations Applique: A surface covering applied by heat and pressure Printing: A process of making a mark or impression onto a substrate for decorative or informational purposes. Painting Hard coating Metalizing/shielding Surface Treatment Annealing Machining

24. FAULTES & REMEDIES in Injection Moulding Products

25. FAULTES & REMEDIES in Injection Moulding Products

26. References: Internet Thanks