Lego Blocks ( Material Engineering )
- 2. LEGO BLOCKS
- 3. INTRODUCTION Plastic construction toys that are manufactured by The Lego Group, a privately held company based in Billund, Denmark. Consists of colorful interlocking plastic bricks accompanying an array of gears, figurines called minifigures, and various other parts. Lego pieces can be assembled and connected in many ways, to construct objects; vehicles, buildings, and working robots.
- 4. LEGO BLOCKS Anything constructed can then be taken apart again, and the pieces used to make other objects.
- 5. RAW MATERIAL FOR PRODUCTION: ABS (ACRYLONITRILE- BUTADIENE-STYRENE COPOLYMER )
- 6. WHAT IS THIS? Acrylonitrile Butadiene Styrene (ABS) is an opaque thermoplastic and amorphous polymer. A hard, tough, heat-resistant engineering plastic . This material has excellent impact resistance and toughness making it ideal for applications. ABS also exhibits a strong resistance to corrosive chemicals. Widely used in appliance housings, luggage, pipe fittings and automotive interior parts.
- 7. CHEMICALLY: ABS is a graft copolymer—that is, a giant molecule. Made up of chains of polybutadiene growing from a backbone chain of styrene-acrylonitrile copolymer . It is made by dissolving polybutadiene in liquid acrylonitrile and styrene monomers and then polymerizing the monomers by the introduction of free- radical initiators.
- 8. CONSTITUENTS: Essentially the three constituents provide a balance of properties: The butadiene units imparting good impact strength. The acrylonitrile units affording heat resistance. Polystyrene gives a shiny and hard surface.
- 9. WHAT ARE THESE ? 1.Acrylonitrile : Synthetic monomer produced from propylene and ammonia.
- 10. 2. Butadiene: This petroleum hydrocarbon obtained from the C4 fraction of steam cracking gives Lego bricks resilience at low temperature.
- 11. 3. Styrene: Styrene is made by dehydrogenating ethyl benzene (which, in turn is made by reacting ethene with benzene).
- 12. Potassium peroxydisulfate, K2S2O8 initiates the polymerization reaction.
- 15. Manufacturing: Lego pieces have been manufactured from a strong, resilient plastic known as acrylonitrile butadiene styrene (ABS). Lego engineers use the NX CAD/CAM/CAE PLM software suite to model the elements. The software allows the parts to be optimized by way of mold flow and stress analysis. Prototype molds are sometimes built before the design is committed to mass production.
- 16. •The ABS plastic is heated to 232 °C (450 °F) until it reaches a dough-like consistency.
- 17. • It is then injected into the molds at pressures between 25 and 150 tones, and takes approximately 15 seconds to cool
- 18. •The molds are permitted a tolerance of up to 2micrometers, to ensure the bricks remain connected.
- 19. •Human inspectors check the output of the molds, to eliminate significant variations in color thickness.
- 22. INTRODUCTION: Injection molding is the most widely used polymeric fabrication process. Unlike molten metals, polymers melts have a high viscosity and cannot simply be poured into a mold. Instead large force must be used to inject the polymer into the hollow mold cavity. More melt must also be packed into the mold during solidification to avoid shrinkage in the mold. The injection molding process is primarily a sequential operation that results in the transformation of plastic pellets into a molded part.
- 23. INJECTION MOLDING MACHINE: An injection molding machine produces components by injection molding process. The main unit of typical injection molding machine are the clamping unit, the plasticizing unit and the drive unit.
- 24. Clamping unit: • The clamping unit holds the mold. It is capable of closing, clamping, and opening the mold. •Its main components are the fixed and moving plates, the tie bars and the mechanism for opening, closing and clamping.
- 25. INJECTION UNIT: •The injection unit or plasticizing unit melts the plastic and injects it into the mold. •The drive unit provides power to the plasticizing unit and the clamping unit.
- 27. Injection molding cycle: STAGE ONE: The mold is closed and the nozzle of the extruder is pushed against the sprue bushing of the mold. The screw, not rotating at this point, is pushed forward so that the plastic melt in front of the screw is forced into the mold.
- 28. STAGE TWO: When the mold is completely filled, the screw remains stationary for some time to keep the plastic in the mold under pressure; this is called the “hold” time. During the hold time additional melt is injected into the mold to compensate for contraction due to cooling.
- 29. Later, the gate, which is the narrow entrance into the mold, freezes. At this point the mold is isolated from the injection unit. However, the melt within the mold is still at high pressure. As melt cools and solidifies, the pressure should be high enough to avoid sink-marks, but low enough to allow easy removal of the parts.
- 30. During the plastication stage, the material is pushed forward from the feed hopper through the barrel towards the nozzle by a rotating screw. When the gate freezes, the screw rotation is started. The period of screw rotation is called screw “recovery”.
- 31. The rotation of screw causes the plastic to be conveyed forward. As the plastic moves forward, heat from the electric heater bands along the barrel and shear starts to melt the plastic. At the discharge end of the screw the plastic will be completely melted. The melt that accumulates at the end of the screw pushes the screw backward. Thus the screw rotates and moves backward at the same time. The rate at which plastic melt accumulates infront of the screw can be controlled by the screw back pressure, that is, the hydraulic pressure exerted on the screw. This also controls the melt pressure infront of the screw.
- 32. STAGE THREE: When the material in the mold has cooled sufficiebtly to retain its shape, the mold opens parts are rejected from the mold. When the molded part has been ejected, the closes and the cycle start over again.
- 33. THE MOLD: Each mold, sometimes referred to as a tool, and is built to exact specifications of the part or parts required by the customers. The mold typically consists of two mold halves. Usually one mold half contains the cavity and forms the outer shape of the part,called the cavity side.
- 34. The other mold half contains a protruding shape and forms the inner shape of the part, this mold part is called the core. When the core is clamped against the cavity, the hollow space that is formed defines the shape of the part to be molded
- 35. MOLD COOLING: During the mold cycle, heat is first required to be put into the material and then the heat must be removed as quickly, as consistently as possible. Cooling allows the plastic to solidify and become dimensionally stable before ejection.
- 36. Heat that has been transferred to the mold by the molten plastic is carried away by acoolant that circulates through cored passages in the mold. Usually running water is used as a coolent for injection molding process.
- 37. PROCESSING PROPERTIES: Processing Temperature 177 - 232 °C Nozzle Temperature 191 - 274 °C Adapter Temperature 200 - 250 °C Die Temperature 200 - 250 °C Melt Temperature 149 - 323 °C Mold Temperature 10.0 - 90.0 °C Injection Velocity 200 - 240 mm/sec Roll Temperature 60.0 - 100 °C Drying Temperature Moisture Content 0.0100 - 0.300 % Dew Point -29.0 - -17.8 °C Injection Pressure 4.14 - 130 MPa Vent Depth 0.00380 - 0.00760 cm Cushion 0.317 - 0.635 cm
- 38. Speed related process and variables: Mold opening and closing speed Injection speed Screw rotation speed Screw recovery speed Component retraction speed
- 39. Pressure related process variables: Injection pressure Holding pressure Hydraulic back pressure
- 40. TIME RELATED PROCESS VARIABLES: Injection time Holding pressure time Pause (dwell) time Cooling time Cycle time
- 41. TEMPERATURE RELATED PROCESS VARIABLES: Melt temperature Mold temperature Barrel temperature Cooling water temperature.
- 42. RECYCLING OF THIS THERMOPLASTIC: As virgin ABS is somewhat expensive, recycling ABS is economically very attractive. Recycled ABS can be blended with virgin material to produce products with lower cost while preserving the high quality.
- 43. ABS is recycled by first shredding used plastics to produce shredded plastics. After this step, metals and undesirable plastics are separated from the shredded plastics to produce separated plastics. This separation process is often accomplished by using a water system with different velocity water streams on top of each other.
- 44. After the material composition of the separated plastics has been analyzed, the recovered ABS can be blended with virgin ABS to produce a desirable recycled plastic. In LegoCompany there is only 1% of scarp plastic.
- 45. Produced Lego Block & It’s Draft Angle:-
- 46. MARKET RESEARCH: LEGO’S MARKET RESEARCH LEGO can be clearly cited as the success story in the toys and games industry over the last few years. Its global toy sales stood at us$ 3.7bn in retail value terms , making company the third largest traditional toy player in the world with 5%of the global market.
- 47. LEGO’S MARKET RESEARCH THROUGH ONLINE COMMUNITIES LEAD USERS: These are the people who are actively engages with on product designs of Lego. COMMUNITY USERS: These are the people whose names and addresses are known to Lego. CONNECTED COMMUNITY USERS: These are the people who have bought Lego product and have also been to either a Lego shop or park.
- 48. PRODUCT INNOVATION DRIVES GROWTH : Lego has traditionally focused on its home category, construction toys, where it has enjoyed dominant status for many years. Lego games were introduced, featuring buildable board games, which gained enough consumer appreciation . Similarly in 2010, LEGO released Minifigures.
- 49. COMBATING AGE COMPRESSION: Another key aspect of LEGO’s strategy has been its successful partnership with a number of developers to release LEGO branded video games. This idea is not so new, HASBRO partners with Electronic ARTs to release electronic versions of its games.
- 50. LEGO BLOCKS MANUFACTURING COUNTRIES: DENMARK PORTUGAL FEBULAND SWITZERLAND HUNGRY CANADA SPAIN MEXICO GERMANY UK FINLAND
- 51. CONCLUSION: The production of Lego blocks seems to be very easy and it can also produce by different plastic molding processes such as extrusion process or compression process etc. The blocks can also produce by different materials such as very well-known thermoplastic PVC or by PLA. The right and suitable material for the production is ABS as describe above its toughness, strength, heat resistance and chemical resistance makes it the material of our choice.
- 52. The Lego group recycled all its waste plastic and only 1% of scarp is produce there. The Lego group also started the virtual games for the children of new generation. The Lego group setup different industries at different places all around the world and continue to spread its roots all around the world.