Mechanical Engineering Metal Forming Virtual Simulation Lab-I Experiments

Multi Step Forging

1. Introduction

Forging is one of the oldest metal-forming processes, traditionally performed by a smith using a hammer and anvil. Modern industrial forging uses hammers or presses powered by electricity, hydraulics, steam, or compressed air.

Forged parts are preferred due to:

  • Compaction of metal and reduction of internal voids
  • Favorable grain flow along the shape
  • Low material waste
  • Ability to shape hard-to-machine materials

Metal forming is classified as:

  • Cold Working – done at room temperature
  • Hot Working – performed above recrystallization temperature

2. Need for Multi-Step Forging

Some components require progressive deformation that cannot be achieved in a single blow. To achieve accurate shape, strength and surface quality:

  • Multiple dies are used sequentially
  • Each die performs a specific deformation
  • Force is adjusted at each step
  • Metal is gradually shaped without defects

3. Steps of Multi-Step Forging

  1. Prepare all dies in the required sequence.
  2. Heat the billet to the correct forging temperature.
  3. Press the billet using the first die to perform initial deformation.
  4. Transfer billet to the next die and apply the second deformation.
  5. Repeat until the final die stage is complete.
  6. Final forged product is obtained after the last pass.

Applications:

  • Valve forming
  • Heading operations
  • Automotive parts, crankshafts, connecting rods

4. Heading Operation (Application of Multi-Step Forging)

Heading is an upsetting process used to produce a larger head on the end of a rod or wire.
Used for: bolts, screws, rivets, nails, fasteners.

Advantages:

  • Very high production rate
  • Can be combined with cold extrusion
  • Stronger parts due to grain flow

Steps of Heading Process

Step 1: Blank Preparation

  • Wire is fed from coil → straightened → cut to required length → blank is produced.

Step 2: Pre-Forming

  • Punch gives initial small deformation.
  • Allows metal to flow smoothly in next stages.

Step 3: Head Formation

  • Tapered head is formed.
  • Severe deformation → improved mechanical properties.

Step 4: Final Shaping

  • Punch presses the tapered head → final head shape (round / hex / square).
  • Final bolt or screw is obtained.

5. Valve Forming (Multi-Step Forging)

A valve controls fluid flow in pipelines, engines, compressors and many industrial applications.

Classification of Valves

  • Ball Valve – fast on/off control
  • Butterfly Valve – high capacity flow control
  • Ceramic Disc Valve – abrasive fluids
  • Check Valve – one-direction flow
  • Gate Valve – low pressure drop
  • Globe Valve – accurate flow control
  • Needle Valve – precise flow metering
  • Plug Valve – rugged on/off control
  • Thermal Expansion Valve – refrigeration systems

(And many more)

Ball Valve – Summary

  • Spherical disc with a port
  • Four types: Full Port, Reduced Port, V-Port, Trunnion
  • Used for emergency shut-off, household plumbing, industrial pipelines

Butterfly Valve – Summary

  • Disc rotates on shaft
  • Low cost
  • Used for large pipe flow regulation

Globe Valve – Summary

  • Regulates flow with disc and seat
  • Accurate throttling
  • Used in water taps, steam lines

Plug Valve – Summary

  • Cylindrical/conical plug rotates to open/close
  • Good for quick shutoff
  • Used in garden hose nozzles, chemical systems

6. Pressure Relief Valves (Safety Devices)

Used to protect equipment from over-pressure failures in boilers, reactors, storage tanks, pipelines.

Types:

  1. Conventional Spring-Loaded Safety Valve
  2. Bellows-Type Safety Valve
  3. Pilot-Assisted Safety Valve

Each operates differently but serves the same purpose—prevent catastrophic pressure buildup.

7. Steam Traps

Devices placed in steam lines to remove condensate and non-condensable gases.
Checked using visual, thermal or acoustic analysis.

8. Wheel Rim Cover – Manufacturing (Cold Forging + Punching)

Method:

  1. Punching holes in aluminum sheet
  2. Punching windows
  3. Cold forging to bowl the cover
  4. Trimming edges on a lathe

9. Summary of Multi-Step Forging Procedure

  1. Heat billet
  2. Use multiple dies sequentially
  3. Control deformation at each stage
  4. Prevent defects like laps, folds, and underfill
  5. Obtain final shape with proper grain flow

10. Applications of Multi-Step Forging

  • Bolts, screws, rivets
  • Valves and valve heads
  • Connecting rods
  • Crankshafts
  • Automotive and aerospace parts