Extrusion blow molding

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1. EXTRUSION BLOW MOLDING PRESENTED BY Fahad Rafiq Reg # 2014-UET-KIT-Mech-21

2. D.R AQ Khan Instetute Mianwali Subject Code : 241 Name Of Subject : Manufacturing Technology Name of Unit : Molding Topic : Extrusion Blow Molding

3. BLOW MOLDING:

4. What Is Blow Molding? “ Blow molding , also known as  blow forming , is a manufacturing process by which hollow plastic parts are formed.” It is used to made hollow parts such as plastic bottles. vido

5. Blow Molding Process The blow molding process begins with melting down the plastic and forming it into a parison . The parison is a tube-like piece of plastic with a hole in one end in which compressed air can pass through. The parison is then clamped into a mold and air is pumped into it. The air pressure then pushes the plastic out to match the mold. Once the plastic has cooled and hardened the mold opens up and the part is ejected. vido

6. Compnents for Blow Molding: 7

7. Historical Development Year Development 1930 The first applications for blow molding were for cellulose nitrate 1940 Introduction of LDPE (Low Density Polyethylene ). With LDPE, the plastic industry growth rapidly 1942 The first polyethylene bottle was manufactured using the blow molding process 1950 The demand for blow molding increases by the mass production of High Density Polyethylene (HDPE) and Polypropylene (PP) for various applications

8. The principle of blow molding A simple explanation of the principle of blow molding is similar to inflating a balloon

9. BASIC PROCESS TWO MAIN PROCESSES TO preform (or parison) of hot plastic resin in a somewhat tubular shape is created. A pressurized gas, usually air, is used to expand the hot preform and press it against a mold cavity. The pressure is held. until the plastic cools.

10. Blow molding processes Blow molding processes Extrusion blow molding Injection blow molding Stretch blow molding ( Classification based on parison/preform formation )

11. What is Extrusion? Extrusion is the process by which a block/billet of metal is reduced in cross section by forcing it to flow through a die orifice under high pressure. Vido

12. Extrusion blow molding ( Courtesy : h ttp://www.et.byu.edu/groups/mfg355/pages/lectures/powerpoint_ppt/13%20blow%20molding.ppt )

13. Extrusion Blow Molding: In  Extrusion blow molding  (EBM), plastic is melted and extruded into a hollow tube (a parison). This parison is then captured by closing it into a cooled metal mold. Air is then blown into the parison, inflating it into the shape of the hollow bottle,  container  or part. After the plastic has cooled sufficiently, the mould is opened and the part is ejected. 1)Reciprocating screw. 2)Compressed air. 3)Hopper. 4)Granules. 5)Barrel. 6)Heaters. 7)Grinding, Mixing. 8)Actuator's hydraulic generator. 9)Draw plate. 10)Core/Punch.

14. Extrusion Blow Mold (Courtesy : http://industrialblowmolding.com/?page_id=22)

15. Extrusion Blow Mold Neck-ring insert Cooling water ports Cut-off insert 1 2 3 1 3 2 (Courtesy : http://industrialblowmolding.com/?page_id=22)

16. Extrusion blow molding: 1 2 3 4 5

17. Blow molding

18. Two important terms: Parison and preform : Parison is the part that is used in blow molding where air is inflated to from the desired shape. It is closed on one end. Here the preform is same as parison but there is thread in the open end in preform. Preform is mostly used in bottles . Figure : Parison Figure : Preform

19. Step 1 Step 2

20. Step 3 Step 4 ( Courtesy : h ttp://www.et.byu.edu/groups/mfg355/pages/lectures/powerpoint_ppt/13%20blow%20molding.ppt )

21. Blow Molding

22. Blow Molding

23. Blow Molding

24. Blow Molding

25. Types of Extrusion blow molding: Continuous Extrusion molding: In extrusion molding, plastics is continuously extruded and the individual parts are cut off by knife. vido Intermittent extrusion molding: In straight intermittent extrusion, extruder screw run ,stops and pushes melt out. Here, accumulator is used to gather the mold. Extrusion blow molding Continuous extrusion molding Intermittent extrusion molding

26. CLASSIFICATION OF EXTRUSION PROCESSES Extrusion By Direction By Equipment By Operating Temperature Indirect / Backward Direct / Forward Hot Cold Horizontal Vertical

27. Process Parameters Parison characteristics size, shape, straightness, wall thickness, mechanical properties Inflation pressure Mold design cooling, venting Blow ratio= Mold diameter/Parison Diameter (1.5 to 3 are common

28. Most thermoplastics can be blow molded Some typical applications are HDPE : High Density Polyethylene (stiff bottle, toys, cases, drum) LDPE : Low Density Polyethylene (flexible bottle) PP : Polypropylene (higher temperature bottle) PVC : Polyvinyl Chloride (clear bottle, oil resistant containers) PET : Polyethylene terephthalate (soda pop bottle) Application (Courtesy : http://industrialblowmolding.com/?page_id=22)

29. Extrusion blow molding: Advantage: Low molding cost resulting from lower pressure used Low tool cost due to simple structure Fast production due to small processing cycle Ability to mold complex part Disadvantage: Limited to hollow parts Low strength of the product

30. Materials used in blow molding: Most thermoplastics can be blow molded Some typical applications are HDPE : High Density Polyethylene (stiff bottle, toys, cases, drum) LDPE : Low Density Polyethylene (flexible bottle) PP : Polypropylene (higher temperature bottle) PVC : Polyvinyl Chloride (clear bottle, oil resistant containers) PET : Polyethylene terephthalate (soda pop bottle)

31. Materials Considerations One critical requirement is that the polymer must have good melt strength. The common blow molded plastics are: Polyolefins HDPE LDPE Polypropylene (PP) PVC PET December 09, 2006 Mitchel Plamondon http:// upload.wikimedia.org/wikipedia/en/2/2a/Soft_drink_shelf.JPG PET bottles are excellent barrier materials and are widely used for soft drinks

32. Factor effecting blow molding : Parison characteristics: Size, shape, straightness, wall thickness, mechanical strength. Inflation pressure: Pressure will be set according to the process. Mold design : Size of the mold, the material the mold is made with. Blow ratio  Here, the blow ratio must be 1.5 to 3 Mold diameter Parison diameter

33. Process Material Blow molded parts can be formed from a variety of thermoplastic materials, including the following: Low Density Polyethylene (LDPE) High Density Polyethylene (HDPE) Polyethylene Terephtalate (PET) Polypropylene (PP) Polyvinyl Chloride (PVC)

34. Advantages of Blow Molding Well suited to low and high production rates. Quick product revisions for increased flexibility. Tooling is less expensive than other molding. Each part price is less than Rotational Molding. Trim and flash reusable into finished parts .

35. Disadvantages of Blow Molding Environmental Disadvantages effecting. Process and Material Limitations. Inability to produce bottles with calibrated neck finishes. Machines typically dedicated to a narrow range of sizes. Trimming required

36. Blow Molding Applications Milk bottles Pharmaceutical bottles Antifreeze bottles Polypropylene bottles Coliseum seats One-piece chair Ice chests and coolers Double-wall player case Garbage cans Drums Fuel tanks

37. Application In Pakistan Industries Tabraiz mold engineering Lahore Pakistan. ( products: pet blow mold, machine parts, labeling parts) Thermosole industries (pvt) ltd. Kotlakhpat. (covering 90% of blow molding automotive market in Pakistan) Kalson engineering in Lahore. (services in mold making) vido

38. Any question?

39. Thank You ! The end