MACHINE TOOLS AND DIGITAL MANUFACTURING
a) Explain the working principle of lathe
b) With the help of a suitable sketch briefly explain the parts of a lathe
c) How do you specify a lathe. Prepare a detailed specification for the lathe available in College Production Engg Lab
2) Lathe operations
a) List the common lathe operations that can be carried out on a lathe.
b) With the help of suitable sketches explain how drilling and boring is done on a lathe
c) Explain with the help of a sketch how taper turning is carried out by swiveling of compound rest
d) List the different work holding devices used in lathe. Explain briefly any two with neat sketches
3) Lathe operations (Contd.)
a) With the help of a suitable sketch explain how taper turning is done using an attachment
b) What are the advantages of using a taper turning attachment
c) With the help of suitable sketches explain the lathe set-up for thread cutting operation
d) With the help of neat labelled sketches explain the Apron Mechanism and feeding mechanism
a) With the help of a suitable diagram explain the working principle of a drilling machine
b) With simple sketches briefly explain different types of drilling machines
c) Differentiate between gang drilling machine and turret drilling machine
a) With the help of a neat labelled sketch briefly explain the elements of a twist drill
b) With the help of neat labelled sketches explain the twist drill nomenclature
c) Differentiate between counterboring and countersinking
6) Metal cutting
a) Sketch and explain the basic machining operation and important parameters?
b) Explain how chip is formed in metal cutting? Explain briefly the different types of chips?
Under what conditions are these chips formed?
c) With the help of neat labelled sketches explain the tool elements and tool angles. Explain tool signature
d) Sketch, compare and differentiate between Orthogonal cutting and oblique cutting.
7) Mechanics of metal cutting
a) Differentiate between forces acting in orthogonal cutting and oblique cutting
b) From first principles derive expressions for shear angle and shear strain
c) During orthogonal cutting with a single point tool having a 0 degree rake angle, the chip thickness is measured to be 1.13 mm, the uncut thickness being 0.2 mm. Determine the
shear plane angle and also magnitude of the shear strain.
8) Merchant circle
a) With the help of a neat sketch explain how Merchant’s Circle Diagram is plotted and what is its uses
b) During orthogonal cutting test, the observations made are as follows: the uncut chip thickness =0.25 mm; measured chip thickness= 1.2 mm; width of cut = 2.5 mm; rake angle =
0 degrees; cutting force = 900 N ; normal force = 810 N. Calculate the mean shear strength of the work material. Also estimate the coefficient of friction between the tool and the chip
c) The following observations were made during an orthogonal cutting operation: rake angle =10 degrees; co-efficient of friction = 0.85; chip thickness = 2.5 mm; width of cut = 15 mm; cutting speed = 40 m/min; feed = 1.5 mm/rev; shear strength = 650 N/sq.mm. Determine the following: chip thickness ratio, shear angle; shearing force, friction angle; cutting force and power consumed at the cutting tool
a) Derive expressions for optimum cutting speed for minimum cost and maximum production rate
b) A cylindrical bar is to be turned. The maximum allowable feed is 0.2 mm/rev and at this feed rate Taylor’s tool life equation for a tool-work combination is found to be vT 0.25 = 75, where v is the cutting speed in m/min and T is the corresponding tool life in minutes. The labour cost and overheads is Rs. 10 per minute and the total cost involved in each regrinding of the tool is Rs. 160. On an average, it takes about 2 minutes to change the tool. Estimate the cutting speed that will lead to minimum cost and maximum production rate
c) When the rake angle is zero during orthogonal cutting, show that