(c) Elaborate the principles of vacuum forming process for thermoplastics, given a shaped form. Question 5 [4] (a) i. Explain the Spin welding process with the help of a diagram. [6] ii. Name the two requirements for the process to be successful? [4] i. Which are the most common fastners used in assembly? [2] ii. Which joining process could be suitable for joining rubber sheet material? [2] (0) i. Give three reasons why mechanical fastners must be kept to a minimum for the assembly process. [37 What are the three things recommended to lower the assembly costs? [3]

I will rate immediately, thank you!

9. During the operation of an extruder in making thin-walled tubing several defects have been encountered that appear to be small globules of resin. Investigation of these globules reveals that they will soften but not melt when heated. Explain what these globules might be and suggest two possible remedies for eliminating them.

What type of polymer: elastomer (rubber), thermoplastic, or thermoset exhibit low creep? Explain why

Question 3 For a 40 wt% Sn-60 wt% Pb alloy at 150 °C and taking the densities of Pb and Sn at 150 °C to be 11.23 and 7.24 g/cm?, respectively. Composition Cats Sn) 20 60 100 327C 600 300 Liquid 500 232'C 200 400 183°C 18.3 61.9 97.8 300 100 200 100 60 80 100 (Pb) Composition (wt% Sn) (Sn) The lead-tin phase diagram a) AN6 marks b) W c) calculate raction. CROmarks d) calculate the relative amount of each phase present in terms of mass fraction volume fraction Temperature ("C) Temperature (F)

Clearly show your work

Compare thermoplastic and thermosetting polymers: (a) according of mechanical characteristics upon heating; and (b) on the basis of possible molecular structures.

Define the term redox reaction.