MANUFACTURING PROCESSES

Which of the following helps in entrapping impurities and debris flowing towards the casting?

How can we calculate the solidification time?

In a machining operation, chip thickness ratio is 0.3 and back rake angle is $10^\circ$. What is the value of shear strain?

Sprue design is made tapered instead of straight

The percentage of total energy dissipated due to friction at the tool-chip interface is

The operation of milling two sides of a workpiece simultaneously is called

Which is the incorrect statement about results of hot working?

Arc length in arc welding should be equal to

The bending force required for V-bending, U-bending and edge bending will be in the ratio of

The material used for coating the electrode is called

Explain the following : $4 \times 2 = 8$ (i) Metal casting elements with neat and clean sketch (ii) Broad classification of casting defects and their subcategories

In a single-pass rolling operation, a 20 mm thick plate with plate width of 100 mm is reduced to 18 mm. The roller radius is 250 mm and rotational speed is 10 r.p.m. The average flow stress for the plate material is 300 MPa. Calculate the power required for the rolling operation in kW.

Differentiate between bulk and sheet metal forming using suitable example.

Write down the assumption in rolling process. With neat sketch of geometry of rolling process, explain the following : Leading zone, lagging zone, location of neutral plane.

A 200 mm long down sprue has an area of cross-section of $600\text{ mm}^2$ where the pouring basin meets the down sprue. A constant head of molten metal is maintained by the pouring basin. The molten metal flow rate is $6.5 \times 10^5\text{ mm}^3/\text{sec}$. Consider the end of down sprue to be opened to atmosphere and an acceleration due to gravity of $10^4\text{ mm}/\text{sec}^2$. Avoid the air aspiration effect. Calculate (i) the height of the pouring basin and (ii) the area of down sprue in $\text{mm}^2$.

With a neat sketch, explain the working principle and recent advancement in the field of additive manufacturing. Also highlight its advantages.

Two castings, a cube and a slab of same material solidify under identical mould condition. The volumes of the castings are equal but the slab dimensions are in the ratio of 1 : 2 : 4. Find the ratio of solidification time of the cube to the slab.

Highlight the properties required for cutting tool materials. List and explain four tool materials along with their key features.

Explain the following welding defects with suitable figures : Slag inclusions, incomplete fusing and penetration, under filling, lamellar tear and distortion.

Following data from the orthogonal cutting test is available : Rake angle = $10^\circ$; Chip thickness ratio = 0.35; Uncut chip thickness = 0.51 mm; Width of cut = 3 mm; Yield shear stress of work material = $285\text{ N/mm}^2$; Coefficient of friction at tool-chip interface = 0.65. Determine (i) cutting force, (ii) thrust force, (iii) normal force at interface and (iv) shear force on tool.

With a neat sketch, explain the metallic powder production using gas atomization method.

State and explain the types of chips formed in machining operation using suitable sketch.

A slot 25 mm deep is to be cut through a workpiece 200 mm long with the help of HSS side and face cutter whose diameter is 150 mm and has 10 teeth. The cutting speed is 50 m/min and feed is 0.25 mm per teeth. Find— (i) table feed in mm/min; (ii) total cutter travel; (iii) time required to machine the slot.

Calculate the melting efficiency in case of arc welding of steel with a potential of 20 V and current of 200 A. The travel speed is 5 mm/sec and the cross-sectional area of the joint is $20\text{ mm}^2$. Heat required to melt steel may be taken as $10\text{ J/mm}^3$ and the heat transfer efficiency as 0.85.

Sketch and explain the geometry and working of an end milling cutter. Also derive the expression for maximum chip thickness in end milling operation.

A steel cup of height 30 mm, internal diameter of 40 mm with a flange of 10 mm width is to be deep drawn from a metallic sheet of 1 mm thickness. Calculate the diameter of blank and drawing force required to perform the operation. Can the cup be drawn in a single operation? Comment based on your observation. [Assume $\sigma_y = 150\text{ MPa}$].

With neat sketch, explain the construction and working principle of a lathe machine.

The pattern used for mass production is

The low permeability in sand can cause which of the following defects in casting?

Power consumption in metal cutting is mainly due to

In orthogonal cutting test, the cutting force = 900 N, the thrust force = 600 N and chip shear angle is $30^\circ$. Then the chip shear force is

In the grinding wheel of $A60\ G7\ B23$, B stands for

Lathe bed is usually made of

Which of the following types of stresses is/are involved in the wire drawing operation?

In rolling process, roller separating force can be decreased by

In straight polarity welding

Arc stability is better with

What is cooling curve in metal casting? With neat sketch, explain the different regions of the cooling curve for a pure metal.

Explain the interparticle friction associated with powder flow. With neat sketch, correlate the interparticle friction with angle of repose.

In a metal cutting operation, chip thickness = 0.62 mm, feed = 0.2 mm/revolution and rake angle = $15^\circ$. Calculate— (i) cutting ratio; (ii) shear angle; (iii) shear strain.

Differentiate between up and down milling operations.

Two castings of same material having similar surface area and in the shape of sphere and cube, find out the ratio of solidification time of sphere to that of cube.

In a wire drawing operation, initial wire diameter is 5.5 mm and final diameter is 5 mm. The die angle is $16^\circ$, die land is 3 mm and coefficient of friction is 0.1. Calculate the drawing load if flow stress is 240 MPa.

Calculate the force acting on the cope box for a casting of cast iron pipe of 12.5 cm outer diameter, 10 cm of inner diameter and length of 180 cm. The metal head is to be about 20 cm and moulding box size is $200 \times 25 \times 20\text{ cm}^3$. Assume the moulding sand and core material is same and having density of $0.0165\text{ N/cm}^3$ and density of molten metal is $0.0771\text{ N/cm}^3$.

Describe the mechanics of rolling process and derive the expression for location for neutral plane and roller separating force.

What is a grinding wheel? Explain the grinding wheel specification.

Determine drawing stress to produce 20% reduction in a 10 mm diameter steel wire. The stress is given by $\sigma = 1300\ \epsilon^{0.3}\text{ MPa}$, die angle = $12^\circ$, coefficient of friction = 0.09. Also calculate the power in the wire drawing when wire is moving through the die at a speed of 3 m/sec.

In a metal cutting operation with a cutting speed of 50 m/min, tool life of 45 min was observed. When the cutting speed was increased to 100 m/min, the tool life decreases to 10 min. Estimate the cutting speed for maximum productivity, if tool changing time is 2 min.

In a machining operation, derive the expression for optimum cutting velocity and tool life for maximum production rate condition.

Two 1 mm thick steel sheets are to be spot welded at a current of 5000 A. Assume $R_c = 200\ \mu\Omega$ and time = 0.2 sec. Calculate total heat generated.

Explain the geometry of a twist drill using suitable figure.

Classify the coating technology based on physical principles. Also highlight the criterion for selection of coating materials and processes.

What is a CNC? Explain its salient features which makes the CNC more effective.

State different types of solid-state welding. Explain any two types.

Write a short note on rapid tooling.

What is turret lathe? State and explain different types of turret lathe with suitable figure.