Question

1. Casting Process Selection (25 marks). The component, shown in Figure 1 is a manifold jacket used in a space vehicle. It is to be made of nickel. It is large — weighing about 7 kg — and has a 3D-hollow shape. The section thickness is 2–5 mm. The requirement on precision is strict (precision = 0.1 mm). Because of its limited application, only 10 units are to be made. Table 1 lists the requirements. Please identify the best manufacturing process for this manifold jacket from the following choices and justify your answer. (a) Sand casting; (b) Permanent mold casting; (c) Shell casting; (d) Investment casting; (e) Centrifugal casting; (f) Die casting Figure. 1 Table 1. Manifold Jacket: design requirements Material Class nonferrous metal Process Class primary, discrete Shape Class 3D-hollow-transverse features Mass 7 kg Minimum Section (thickness) 2-5 mm Precision (Tolerance) 0.1 mm Batch Size

Answer 1

To design any component we have to focus on some important aspects regarding design :-

1.Material

2.Complexity of Design

3.Precision and Tolerance

4.Size and shape

5.Production Rate

Explanation :

1.Material :- Here we have to use Nickle which is a non- ferrous material so for this reason the best method available here is shell casting and Die casting method both can be used.

2.Complexity of design :- the design seems to be complex. so for that we have to simply the design when we produce it so we make a pattern in a semi circular cylinder so the best option for that by using this pattern is shell casting process.

3.Precision and tolerance :- As we can see the precision in.    the design is too high so to maintain these kind of precision we can choose either shell casting or investment casting process.

4.Size and shape :- the size of the casting is medium and . shape is hollow so the best method we can use for that is shell moulding process.

5. Production rate:-  As we can see the production rate is not a problem here we have to produce it in a batch quantity so best method available here is shell casting process and investment casting process.

Conclusion :- from the every aspects we can figure it out the best method would be option (c) shell casting.

Shell casting process :-

- In this process we use fine silica with a small amount of thermosetting phenolic resin (6-10%) which is act as a binder.

-This mixture of sand and thermosetting resin make easier to cast thin section with any precision.