Question

A face milling operation is used to machine 5 mm from the top surface of a rectangular piece of aluminium 400 mm long by 100 mm wide. The cutter has four teeth (cemented carbide inserts) and is 150 mm in diameter. Cutting conditions are: v=3 m/s,f=0.27 mm/ tooth, and d=5.0 mm. Determine: (a) time to make one pass across the surface, and (5) (b) metal removal rate during cutting. (5) [10]

Answer 1

The time to make one pass across the surface is approximately 282.8 seconds, and the metal removal rate during cutting is approximately 1.215 mm³/s.

Step-by-step explanation:

To determine the time to make one pass across the surface, we need to calculate the cutting speed. The cutting speed (v) can be calculated using the formula v = n * π * D, where n is the rotational speed of the cutter in rev/min and D is the diameter of the cutter in mm. In this case, the rotational speed is 3 rev/min and the diameter is 150 mm. Substituting these values into the formula, we get v = 3 * π * 150 = 450π mm/min. To convert this to m/s, divide by 1000: v = 450π / 1000 = 1.414 m/s.

The cutting time can be calculated using the formula t = l / v, where l is the length of cut in mm and v is the cutting speed in m/s. In this case, the length of cut is 400 mm. Substituting the values, we get t = 400 / 1.414 = 282.8 seconds. Therefore, the time to make one pass across the surface is approximately 282.8 seconds.

The metal removal rate during cutting can be calculated using the formula MRR = f * v * n, where f is the feed per tooth in mm/tooth, v is the cutting speed in m/s, and n is the number of teeth. In this case, the feed per tooth is 0.27 mm/tooth, the cutting speed is 1.414 m/s, and the number of teeth is 4. Substituting these values into the formula, we get MRR = 0.27 * 1.414 * 4 = 1.215 mm³/s. Therefore, the metal removal rate during cutting is approximately 1.215 mm³/s.