Manufacturing Practices (BT-106) - Important Questions

Explain the steps involved in the sand casting process. Discuss types of patterns, pattern materials, pattern allowances and the role of the gating and riser system in ensuring casting quality.

Explain the principles of Shielded Metal Arc Welding (SMAW) and Oxy-Acetylene welding. Describe common welding defects and their remedies.

Explain the working principles of TIG and MIG welding. Compare TIG, MIG and SMAW with respect to heat input, weld quality, productivity and typical applications.

Describe common machining operations (turning, milling, drilling). Derive the expression for Material Removal Rate (MRR) and give the formula to calculate spindle speed for turning. Use the relation $$MRR = A_c \times V$$ where $A_c$ is the cross-sectional area of cut and $V$ is the cutting speed. Also give spindle speed as: $$N = \left( \frac{1000\,V}{\pi\,D} \right)$$ where $D$ is diameter in mm and $V$ is in m/min.

Define tool life and explain the factors affecting it. State and explain Taylor's tool life equation $$V\,T^{n} = C$$ where $V$ is cutting speed, $T$ is tool life, and $n,\,C$ are constants. Explain how this relation is used to determine cutting speed for a desired tool life.

Explain the processes of annealing, normalizing, hardening and tempering of steels. Describe the microstructural changes associated with each process and typical temperature ranges used.

Draw the Iron–Carbon (Fe–C) equilibrium diagram and explain the eutectoid and eutectic reactions and the critical points. Describe the transformations occurring during slow cooling of a 0.8% C steel (eutectoid composition).

Explain the system of limits, fits and tolerances. For a shaft of nominal size 50 mm, explain the H7/h6 fit and calculate the maximum clearance and maximum interference given limits: H7 = +0.025/+0.000 mm and h6 = +0.000/−0.013 mm.

Explain the principles, advantages and limitations of the following non-destructive testing (NDT) methods: Ultrasonic Testing (UT), Radiographic Testing (RT), Dye Penetrant Testing (DPT) and Magnetic Particle Testing (MPT).

List and explain the Personal Protective Equipment (PPE) commonly used in manufacturing workshops. Describe general workshop safety rules and fire safety measures, including classes of fire and appropriate fire extinguishers.

Explain the basic elements of CNC programming. Write a simple G-code sequence to face a 100 mm length of a 50 mm diameter shaft on a CNC lathe at a spindle speed of 800 rpm and feed of 0.2 mm/rev. Assume the starting position is $Z = 0$.