1.
Technological Trends in Hot Forging Practice
Manohar M Hegde

2.
Blending of traditional practice with the latest developments in
computational, sensing, and control technologies in all stages of
the complete process chain
Technological Trends in Hot Forging Practice
Predict and optimize the process outcome using computational
simulation method, and achieve the process parameters using
closed loop control techniques.
Trend :
Principle:

3.
Technological Trends in Hot Forging Practice
Motivating factors shaping the trends
1. Reduction in wastage of raw material - Net /Near net shape
2. Improved accuracy and finish – Precision forming
5. Reduction in development time – faster to market
3. Reduced energy consumption through minimum billet re-heating
4. Increased productivity / reduced in-process rejection

4.
Typical Process Chain in a Hot Forging Shop
Billet
Preparation
Die
Manufacturing
Billet
Heating
Billet
Pressing
Heat
Treat
ment
Materi
al
Inwar
ding
Technological Trends in Hot Forging Practice

5.
Process
Parameters
Manufacturing
Loop
Simulation
Loop
Process
Results
Prediction of Process Output Through Digital Simulation
Technological Trends in Hot Forging Practice

6.
Simulation of Metal Flow - Main Control Factors
Realization of prediction depends upon the ability to
control the process parameters
1. Precision of the die cavities
2. Shape and weight of billet
3. Temperature of billet and die surfaces
6. Metal flow pattern in the die cavity
4. Friction between die surface and flowing metal
5. Forging force and rate of force application
Technological Trends in Hot Forging Practice

7.
1. Precision of The Die Cavities
a) Direct machining – using conventional (high speed) machining
process
b) Die sinking – using Electro-Discharge Erosion (EDM)process
- Achieve dimensional accuracy
- Achieve surface finish
- Maintain productivity
Objectives :
Technological Trends in Hot Forging Practice

8.
Technological Trends in Hot Forging Practice – Precision of the die cavities
a) Direct machining :
Die blockCutting tool
Clean operation
Flexibility
Rate of material removal
Cutting Complex shapes
Cutting extremely hard material

9.
Technological Trends in Hot Forging Practice-Precision of The Die Cavities
b) Die sinking
Complex shape creation
Extremely hard material
Repeatability
Rate of material removal
Safety (fire hazard)
Power consumption
1. Graphite Electrodes
2. Metal Electrodes
Die Sinking
Spark
Liquid
Electrode
Choice of electrodes:

10.
Die making methods and the achievable accuracies
( microns)
Technological Trends in Hot Forging Practice-Precision of The Die Cavities
SurfaceRoughness,inµmlessthan→
Dimensional Accuracy, in µm, less than →
20015105
0 10050 150 200
Hot Hobbing Milling
Cold Hobbing
EDM
Turning

11.
2. Precision of The Billet Shape and Size
Objective
Technology
a. Achieve dimensional accuracy
b. Maintain productivity
a. Metal cutting
b. Metal shearing
Methodology a. Saw cutting (band or circular cutter)
b. Shearing (precision billet shearer )
d
l
Technological Trends in Hot Forging Practice

12.
3. Accurate Thermal Status of The Billet
Objective
Technology
Methodology
2. Temperature sensing
3. Modular Induction Billet Heating to achieve uniform heating
1. Predicting the temperature profile of the billet by simulation
Achieve uniform temperature field in the billet
Simulation of Billet
Heating Process Control
Billet Heating Controller
Induction Billet Heating Modules
Technological Trends in Hot Forging Practice

13.
3. Accurate Thermal Status of The Dies
Objective
Technology
Controller
Methodology
Predicting the temperature profile of the dies by simulation,
die bulk temperature sensing, and controlled heating and
cooling of die to achieve consistent die temperature.
Achieve uniform distribution of temperature value used
in forging simulation
Infrared Sensor-Optical FiberDie Heating Element
Technological Trends in Hot Forging Practice
Upper die
Lower die

14.
4. Frictional Characteristics During Metal Flow
Objective Reduce resistance to the flow of hot metal by suitable
lubrication
Technology
Controlled delivery of lubricant
(composition, spraying equipment,
pressure, duration) and maintain die
surface temperature
Methodology
Technological Trends in Hot Forging Practice
Sensitivity trials through multiple step
forging simulations to determine the right
friction value and the corresponding die
temperature for a given choice of
lubricant.

15.
5. Forging Force and Rate of Force Application
Closed loop control of ram to achieve an optimized ram
movement
Modulate forging press ram movement to match the
movement pattern used during simulation
Servo controlled
forging presses.
Objective
Technology
Methodology
Modulation of ram movement as per program
Technological Trends in Hot Forging Practice

16.
Closed loop servo control of ram movement to reduce the
contact time between dies and the hot billet
Modulate forging press ram movement to reduce the heat
transferred to the tool, to increase tool life
Predict the thermal load
transfer behavior through
simulation
Objective
Technology
Methodology
StrokeofRam
Time
Conventio
nal drive
Servo drive
Die contact
time due to
servo drive
Original Die
contact
time
Scope of
forging stroke
Technological Trends in Hot Forging Practice
5. Forging Force and Rate of Force Application

17.
Create forged part to Net shape /Near net shape
Accurate thermo mechanical simulation of pre-forming
and final forming stages, considering billet condition,
ram movement, die movement and punch movements.
Objective
Technology
Methodology Create closed die environment using multiple die elements,
nudge the metal in the direction where metal filling is
required by selective movement of individual die elements.
6. Metal flow Pattern in The Die Cavity
Technological Trends in Hot Forging Practice
a. Closed Die with optimized gutter
b. Closed Die with die holding /locking mechanism
c. Closed Die with spring /cushion and counter punch

18.
Closed die with optimized gutter
Technological Trends in Hot Forging Practice – Flashless /Flash reduced Forging
Optimize flash gutter parameters using simulation
Upper Die
Lower Die Ejector Pin
Billet
Forging Force
Parting Line
Land
Flash
Thickness
Gutter
Flash
Flash
- Reduced in-process rejection
- Reduced flash
- Reduced forging force

19.
Closed die with die holding /locking mechanism
Technological Trends in Hot Forging Practice – Flashless /Flash reduced Forging
Use Positive mechanical locking between upper and lower
dies during press action, enclosed die cavity and counter
pressure to achieve flow of hot metal in the optimum path
Die Closing
Force
Upper Punch
Lower Punch
Upper Die
Lower Die
Billet
Forged Job
Metal Flow
Lines
- Improved material yield

20.
Closed die with spring/cushion and counter punch
Technological Trends in Hot Forging Practice – Flashless /Flash reduced Forging
Use of cushions/ springs for upper and lower dies during press
action, enclosed die cavity and counter pressure to achieve flow of
hot metal in the optimum path
Slider
Upper Die
Lower Die
Bolster
Billet
Lower
Punch
Upper
Punch
Upper Die
Cushion
Lower Die
Cushion
Forging
- Reduced number of forging steps
- Reduced in-process rejection

21.
To conclude…
2. The industry has to supplement the traditional
practice with state-of-the-art technologies to fulfil the
increased customers’ expectations.
1. In the current environment, economic considerations
demand that hot forging industry be more efficient in
resource utilization and new product development.
3. Combining the use of computational simulation tools,
latest sensing technology, and software based closed
loop control system enables the industry to meet the
market challenges