Development Of Aerospace and Materials Engineering
Project Aim And Summary: This thesis consists of six main chapters.
Chapter 1 gives a general introduction to the thesis.
Chapter 2 discusses the general concepts involved with process and material selection as well as brief descriptions of aluminum alloys, casting processes and simulation of casting processes.
Chapter 3 lays down the main tasks performed and decisions made prior to simulation, which includes modification of the geometry as well as choice of material (alloy) and process. Chapter 4 presents some simulation results and discusses various changes and improvements made on the simulation of the processes.
Chapter 5 gives a rough cost estimation of the chosen processes and the last chapter.
Chapter 6 gives the conclusion part of the whole thesis.
In addition, reference materials used for this thesis and an appendix, consisting of various tables and figures, are provided in chapters 7 and 8 respectively.
The aim of this thesis work was to:
1. Modifying the products geometry to have better castability
2. Choose a casting process
3. Choose an alloy material
4. Have a sample gating system
5. Show areas susceptible to defects
6. Proposal of secondary processes and testing
7. A rough cost estimation
Abstract: Most aircraft component are currently being manufactured by machining, forging, welding and also assembling such parts. However, the possibilities of cutting cost from a single component has brought about a growing trend towards looking into casting as a possible option for manufacturing aircraft parts. This thesis was done at the request of Saab Avitronics. It evaluates the possibilities of one aircraft part, a chassis for an electronic unit that was first designed to be machined from a blank, to be cast. The thesis goes through the multifaceted tasks of product development. Casting process selection, cast alloy selection as well as geometry modification were some of these tasks that were performed in this thesis. It also evaluates the performances of chosen casting processes, the design of gating systems as well as various process parameters set, by simulating the casting processes. The alloy chosen was A356.0 with a T6 temper and the casting processes chosen were plaster mold casting and rheocasting. The geometry of the original chassis, which had very thin sections and undercuts which were complex to cast, was modified and made easier to cast with an acceptable slight increase of mass and size. The modification done on the geometry as well as the gating systems used had proven to be worthwhile, as the simulation of both process showed that such a part can be casted with no crucial defects foreseen. However, probable cavities might occur at the very tip of the chassis‟s thin-fins – that it has for carrying away heat. Minor subsurface porosities might also be formed, which would not impair the function of the chassis. The modified chassis was made as close to as finished piece as possible, for the purpose of reducing machining costs. The cost of producing such a part by casting was also seen to be much less than machining it from blank. This could be taken as rationale for casting the chassis with thicker sections, to avoid problems that may arise in casting, and to subsequently machine these faces later, as it would still be cheaper than machining the chassis from a blank.
Key Words: design for casting, casting process selection, simulation of rheocasting, simulation of plaster mold casting, casting cost estimation.
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