Answers Answers to the Robin Day ''Polyprop'' questions. 1. Polypropylene was invented in 1953. 2. Functionality and longevity are factors that, for Day, are absolutely fundamental to good design. "Things should be made because they are better and with regard to the limited resources of the planet, so they should be re-usable and long-lasting''. 3. The Royal Festival Hall. Day was commissioned to design the tip-up seating for the new Hall in 1951. ''Cinema and theatre seating had always had upholstery over wooden frames, and I did the whole thing in steel. The seating had anatomical sections with moulded latex foam fitted into pressed seat-pads - the construction was quite enterprising for those days. People said I was absolutely crazy, but, in fact, it's still there, working and comfortable." Answers to the Injection moulding questions. 1. Moulds used in Injection moulding should be hardwearing and durable. Choose which material should be chosen to make a mould for a run of 10,000 mouldings? Brass copper lead Stainless Steel 2. In an Injection moulding machine the plastic is forced into the mould by? Air Pressure Gravity A Hydraulic Ram Pneumatic Pressure 3. Name three thermosetting plastics which are commonly used to create Injection Moulded products ? ABS U.P.V.C High Impact Polystyrene (H.I.P.S) 4. Injection Moulding usually uses which type of plastic? Thermoplastics Thermosetting plastics 5. Which type of screw is used to carry the plastic to the mould? Half Round Archimedean Screw Slot Head 6. Explain how gears were made before the introduction of Injection moulding? They were machined individually. 7. II the gears were made individually instead of on mass what effect would this have on the unit cost of each gear? The unit cost would be far more expensive.