Questions
8 questions in major PSU papers
Difficulty
Medium
Importance
Core — never skip
Overview
Manufacturing and Production Engineering covers the transformation of raw materials into finished components through processes like casting, forming, and machining. It is a cornerstone of mechanical engineering exams, requiring a deep understanding of process parameters, material behavior, and tool geometry. Mastering this topic is essential for securing high marks in PSU technical assessments.
Casting & Metal Forming
Casting focuses on solidification patterns and gating systems, while metal forming deals with plastic deformation without loss of material. In exams, questions often center on fluidity, cooling time, and force calculations in rolling or forging.
- Chvorinov's Rule: ts = C(V/A)^n
- Draft allowance in forging
- Rolling load: P = L * w * avg_flow_stress
- Pouring basin and riser design principles
- Defects: Misrun, cold shut, blowholes, porosity
Welding Technology
Welding involves joining metallic parts through fusion or pressure, with distinct characteristics for arc, gas, and resistance welding. Candidates must be familiar with power sources, heat input, and the identification of common weld discontinuities.
- V-I characteristics: V = V0(1 - I/Is)
- Heat Input formula: H = (V * I * eff) / v
- Types: TIG, MIG, Submerged Arc, Friction Stir
- Weld defects: Undercut, slag inclusion, spatter, lack of fusion
Metal Cutting & Tool Geometry
This section covers the mechanics of chip formation, tool wear, and the geometry of single-point cutting tools. Understanding the relationship between cutting forces and shear plane angles is critical for solving numerical problems.
- Merchant's circle diagram and force analysis
- Taylor's Tool Life Equation: VT^n = C
- Tool geometry: Orthogonal vs Oblique cutting
- RAKE angle, clearance angle, and nose radius influence
- Chip thickness ratio: r = tc/tc_un = sin(phi) / cos(phi - alpha)
Machining Operations & CNC
Operations include turning, milling, and drilling, characterized by specific kinematics and material removal rates. Modern exams increasingly focus on basic G-code programming, coordinate systems, and precision metrology instruments.
- MRR for turning: MRR = f * d * v
- Milling: Up-milling vs Down-milling characteristics
- CNC G-codes: G00 (rapid), G01 (linear interpolation)
- Metrology: Limits, fits, tolerances, and comparator types
- Drilling time: t = (L + approach + overtravel) / (f * N)
Formula Sheet
V * T^n = C
F_s = F_c cos(phi) - F_t sin(phi)
ts = C(V/A)^2
MRR = f * d * v
r = tc/t = sin(phi) / cos(phi - alpha)
Exam Tip
Memorize the Taylor's Tool Life Equation and Merchant's Circle relations as they are the source of most high-frequency numerical problems in PSU exams.
Common Mistakes
- Confusing the specific geometry angles in ASA vs ORS systems for single point tools.
- Neglecting the effect of tool nose radius on surface finish and cutting force calculations.
- Miscalculating cooling time in casting by failing to account for the actual surface area of the riser.
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