please help. Instructions: You will be considering important parameters that wil

Question

please help.

Instructions: You will be considering important parameters that will guide the design of a casting process. Choose o cast part from the back of this sheetid Hd These parts are all made by casting (as well as other processes). Give at least 2 reasons casting is a good way to make the part you have chosen. 1. What environment will this part experience and what requirements will that put on the material you choose? (e.g.- high heat or cold or water or high forces or..) Consider normal and abnormal use conditions. 2. Choose a cast material for your part. Base your decision off of the material's strength, corrosion resistance, looks, purpose, weight, etc. Section 7-3 in the book (p154/194) will be helpful. Remember that sometimes a material that has most characteristics that you need can adopt other characteristics using coatings (like paint) and surface treatments (like galvanized steel or anodized alum.) JUSTIFY your decision -how does the material meet your needs and where does it lack? 3. What is an estimated volume and weight for your part? (very rough estimate of volume based on estimated dimensions, then calc mass) 4. List important service characteristics for your part (smooth, rough, aesthetics, internal passages, etc.) What part characteristics will be important in selecting a casting process? Examples include surface finish, complex geometry, part size, holes or cavities at many angles, temperature of material, etc. 5. Make an estimate of how many parts you might need to make during a year. This will be a guess, but give some reasoning (example: downtown B'Ham has parking bollards, I think we could sell this design to 5 cities per year, therefore I need bollards, or most buildings have _bollards around them, our design is good so we could outfit 700 buildings per year so we need bollards.) 6. Using the material you chose and the number of parts, select a casting process to make your parts. JUSTIFY your decision. Table 7.3 on page 197/237 will be helpful. NOTE: you may NOT select Permanent Mold or Die Casting 7.

Explanation / Answer

Cabinet Hardware (Handle):

?1) Advantages of casting process:

2) This component will be used in offices so it will be experiencing room temperature conditions (about 20°C). Its function will be to pull or push the door (or any other drawer) in the office. Thus it will face both compressive and tensile forces whose magnitude depends upon the moment arm applied by the user. (Moment arm = Force applied by user x Distance of handle from door hinge).

3) Cabinet hardware materials normally include solid brass, Bronze, Stainless Steel, Crystal, Marble, Zinc, Pewter, Glass, Stone and Wood. Among these materials, Stainless Steel is the best choice for door handles. It is due to its high tensile yield strength of 215 MPa and Young’s modulus of 200 GPa with 70% elongation at break which can sustain the forces exerted by user with a high factor of safety. It can also provide good surface finish, corrosion and wear resistance with minimum gross weight. All these properties make it suitable for the cabinet handle to function properly. One disadvantage is that casting of Stainless Steel is a slower process as compared to other casting materials due to oxidation process involved.

4) Normally, the handles are 96 to 128mm in sizes (center to center distance from one screw hole to another). The rod diameter is 20 to 30mm. Assuming it as a cylinder, its volume be,

V = ?r2h = 3.1415 x (15)2 x 128 = 90475.2 mm3

W = Volume x density = 90475.2 x 10-3 (cm3) x 7.86 (g/cm3) = 711.13 grams

5) Service Characteristics that are important in selecting a casting process: surface finish, complex shape, overall dimensions of part, geometrical tolerances for screw holes, ergonomics (easy for user to grab the handle) and internal stresses induced.

6) We will target a city having around 10000 offices. Out of them, we can deliver our product to only, say 2000 offices (due to huge market competition). Each office has around 200 doors which need this handle. So total handles needed in a year will be 2000x200=400000 items/year.

7) Since our part does not have any internal or external features, shell mold casting is best suitable for this part as it lowers the complexity of the manufacturing process and cost as well.

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