Question

Question 1 2) Manufacturing processes can be classified into 2 (Two) major groups. Briefly describe the characteristics of each group. Aid your answer with hierarchy. (10 marles) 1) Sand casting is a process for casting metal in sand molds. Explain FIVE (3) sand casting benefits to the industry (marks) Riser, also known as feeder, is an important part in a sand mold. Briefly describe the function of a riser in a sand casting mold Hence, illustrate the possible types and positions for riser in a sand casting mold. (10 marks) (Total: 25 marks) Question 2 2) Machining cannot be eliminated from many manufacturing industries. Esplain the advantages and disadvantages of machining (10 marks) b) Discuss THREE () types of chips in metal cutting process. (9 marks) A slab-milling operation is being carried out on a 300-mm-long. 100-mm-wide annealed mild-steel block at a feed f= 0.25mm tooth and a depth of cut d = 3.0 mm. The cutter is D=50 mm in diameter, has 20 straight teeth rotates at N=100 rpm, and by definition is wider than the block to be machined Calculate the material-removal rate RR (4 marks) d) A 150-mm-long 125 mm diameter 304 stainless steel rod is being reduced in diameter to 120 mm by turning on 2 lathe The spindle rotates 2 = 400 rpm, and the tool is traveling at an asial speed of 200 mm min. Determine its cutting speed (2 marks) (Total: 25 marks)

Answer 1

a) Manufacturing can be broadly classified into two major categories.

1. Metal Additive Processes
2. Metal Removal/Subtractive Processes

(see fig 1 for hierarchy)

Manufacturing Үноо 08 Material & Addition Material Rencoval to Machining Drilling lalting Casceng → 3D printing lete) فاليريدها حل letes Peg 1. classifican of Manufacturing Pelousies

Characteristics of each group are:

Metal Additive Processes:

• Material / Metal Additive Processes are the processes where the material added in the process. For example, casting, 3D printing etc.
• This process leaves to less wastage of material
• It often requires less energy to produce the final products.

Metal Removal/Subtractive Processes:

• These are the manufacturing processes where the final product is formed by the removal of material example drilling, boring, cutting, machining,etc.
• This process leads to wastage of material.
• A higher amount of energy is required to remove the material.

b) Five major benefits of sand casting top industry are:

1. Removed metal from the casted product can be reused to reduce wastage of material
2. Sand molds are inexpensive and can be produced in large numbers.
3. Sand casts can include directional cooling, bu using chills, hence material properties can be altered to suit the needs.
4. Almost any metal can be sand cast therefore it gives a wide spectrum of choice to the industry.
5. The sand casting process can be easily automated for improved productivity.

c) The major functions of a riser in sand casting are:

• To store a sufficient amount of liquid metal so as to compensate for the volumetric shrinkages in the solidification stage of the casting.
• Open risers help provide enough pressure on the liquid metal in the mold to keep it from forming excessive blowholes.

Possible types of risers are:

• Top risers: This riser is placed on the top of the cavity.
• Side riser: This riser is placed along the cavity in the mold.
• Blind Riser: This riser is not open to atmosphere and can be placed both at top or side of the cavity.

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