Production Engineering Notes for SSC JE Mechanical Engineering

Production engineering (manufacturing) covers the processes by which raw materials are changed into useful products, such as casting, welding, machining and forming. It gives easy and scoring questions in the Mechanical Engineering paper of SSC JE. These production engineering notes for SSC JE explain the main processes, the machine tools, the formulas and the measuring instruments in simple tables with practice questions.

Casting

• The properties of moulding sand are permeability, refractoriness, cohesiveness and collapsibility.
• Common casting defects are blow holes, misrun, cold shut, shrinkage cavities and hot tears.
• Types of casting: sand casting, die casting, centrifugal casting and investment (lost wax) casting.

Welding

Machine Tools and Operations

Cutting Parameters and Tool Life

Example. A job of 100 mm diameter turns at 300 rpm. Cutting speed = π × 100 × 300 / 1000 = 94.2 m/min.

Metal Forming

Metrology (Measurement)

• Vernier calliper: least count = 1 main scale division − 1 vernier scale division.
• Micrometer screw gauge: least count is usually 0.01 mm.
• Limits, fits and tolerances: clearance fit (shaft is smaller than the hole), interference fit (shaft is larger than the hole) and transition fit (in between).
• Slip gauges are used as the standard of length, and go and no-go gauges are used to check the size of the parts quickly.

Heat Treatment of Steel

Modern Manufacturing

• CNC machines are controlled by computer programs and give high accuracy.
• Non-traditional machining includes EDM (electrical discharge machining), laser and ultrasonic machining.
• 3D printing (additive manufacturing) builds a part layer by layer.

Quick Tips

• Remember the allowances of a pattern: shrinkage, machining, draft, shake and distortion.
• Remember the 450 degrees Celsius limit between soldering and brazing.
• Use V = π D N / 1000 with D in mm and N in rpm.
• Remember the order of the heat treatments and their purpose.

Quick Revision Points

• Pattern is made larger than the casting by allowances.
• TIG uses a non-consumable electrode and MIG uses a consumable electrode.
• Soldering is below 450 degrees Celsius and brazing is above.
• Cutting speed V = π D N / 1000.
• Annealing softens steel and hardening makes it hard.

Practice Questions With Answers

1. What is the purpose of a riser in casting?
   Answer: To feed the molten metal and compensate for shrinkage
2. Which welding uses a non-consumable tungsten electrode?
   Answer: TIG welding
3. Which flame is used for welding steel in gas welding?
   Answer: Neutral flame
4. What is the limit between soldering and brazing?
   Answer: 450 degrees Celsius
5. What is the formula of cutting speed?
   Answer: V = π D N / 1000
6. Find the cutting speed for D = 50 mm and N = 600 rpm.
   Answer: 94.2 m/min
7. Which tool material is 18-4-1?
   Answer: High speed steel
8. Which fit has the shaft larger than the hole?
   Answer: Interference fit
9. Which heat treatment softens the steel?
   Answer: Annealing
10. Which operation makes a hole in sheet metal?
    Answer: Piercing

How to Practise This Chapter

Make tables for casting terms, welding types and heat treatments and revise them daily, and practise two cutting speed numericals. Then solve questions from our practice papers and the previous year papers page. Read the previous chapter, Fluid Mechanics and Hydraulic Machines, and see all topics on the SSC JE Mechanical Engineering notes page. Also read the General Science notes for materials.

Frequently Asked Questions

What is production engineering?

Production engineering is the study of the manufacturing processes that change raw materials into finished products.

What is a pattern in casting?

A pattern is a replica of the product, used to make the cavity in the mould. It is made bigger than the product by allowances.

What are pattern allowances?

They are the extra dimensions given to the pattern for shrinkage, machining, draft, shake and distortion.

What is the difference between soldering and brazing?

Soldering uses a filler metal that melts below 450 degrees Celsius, and brazing uses one that melts above 450 degrees Celsius.

What is the difference between TIG and MIG welding?

TIG uses a non-consumable tungsten electrode, while MIG uses a consumable wire electrode.

What are the operations of a lathe?

The main operations are turning, facing, taper turning, threading, knurling, boring and drilling.

What is the formula of cutting speed?

Cutting speed is pi times the diameter in mm times the rpm, divided by 1000, in metres per minute.

What is Taylor's tool life equation?

It is V T to the power n equals C, which relates the cutting speed to the life of the tool.

What is the least count of a vernier calliper?

It is the difference between one main scale division and one vernier scale division.

What is tempering?

Tempering is heating the hardened steel to a lower temperature to reduce its brittleness and to increase its toughness.

Is production engineering important for SSC JE Mechanical?

Yes. It gives easy factual questions in the Mechanical Engineering section every year.

How many questions come from production engineering in SSC JE?

Usually three to six questions come from production engineering, but the number changes from year to year.