1. Two thousand bars 80 mm in diameter and 300 mm tong must be turned down to 65 mm diameter for 150 mm of their length. The surface- finish and accuracy requirements are such that a heavy roughing cut (removing most of the material) followed by a light-finishing cut are needed. The roughing cut is to be taken at maximum power. The light- finishing cut is to be taken at a feed of 0.13 mm, a cutting speed of 1.5 m/s, and at maximum power, If the lathe has a 2-kW motor and an efficiency of 50%, calculate the total production time in kiloseconds (ks) for the batch of work. Assume that the specific cutting energy for the work material is 2.73 GJ/m}, the time taken ¢o return the tool to the beginning of the cut is 15 s, and the time taken to load and unload a workpiece is 120 s. 2. A workpiece in the form of a bar 100 mm in diameter is to be turned down to 70 mm diameter for 50 mm of its length. A roughing cut using maximum power and a depth of cut of 12 mm is to be followed by a finishing cut using a feed of 0.1 mm and a cutting speed of 1.5 m/s. Tt takes 20 s to load and unload the workpiece and 30 s to set the cutting conditions, set the tool at the beginning of the cut and engage the feed. The specific cutting energy for the material is 2.3 GJ/m’, and the lathe has a 3-kW motor and a 70% efficiency, Estimate: a, The machining time for the rough cut b. The machining time for the finish cut c. The total production time for each workpiece3. A 50 mm diameter bar is to be screw-threaded, for 250 mm of its length, on a lathe. The included angle of the thread is 60 degrees, the pitch is 2.5 mm, and the outside diameter of the threaded portion is to be 50 mm. a, If the undeformed chip thickness is limited to 0.13 mm, how many Passes of the tool will be required to complete the operation? b. If the rotational frequency of the workpiece is 0.8 s~' and it takes 20 s to return the tool and engage the carriage with the lead screw after each pass, what will be the total production time? 4. A 1.5 m diameter disc with a 600 mm diameter hole in the center is to be faced, starting at the outside, on a vertical-boring machine, The rotational frequency of the table is 0.5 s*, the feed is 0.25 mm, and the back engagement (depth of cut) is 6 mm. The specific cutting energy for the work material and the particular cutting conditions is 3.5 GJ/m. Calculate: a. The machining time, in kiloseconds b. The power consumption (in kW) at the beginning of the operation ¢. The power consumption just before the end of the operation 5. In a pipe flange facing operation carried out on a lathe, the depth of cut is 12 mm, and the inside and outside diameters of the flange are 250 mm and 500 mm, respectively, The specific cutting energy of the work material is 2.6 GJ/m*, the maximum rotational frequency of the lathe spindic is 6 s~!, and the maximum feed that can be applied is 0.25 mm. The major cutting-edge angie of the tool is 60 degrees. Find: a, The maximum power required for machining when the machine is operating at maximum capacity b. The cutting force c. The machining time