high velocity forming

Seminar Seminar

onon

Thapar University, Patiala(Department of Mechanical Engineering)

Presented by:Presented by:Gopal Krishan DixitGopal Krishan DixitRoll No. – 800882001Roll No. – 800882001

M.E.(Prod. & Inds. Engg.)M.E.(Prod. & Inds. Engg.)

• Sheet metal forming is a process that materials

undergo permanent deformation by cold

forming to produce a variety of complex three

dimensional shapes.

SHEET METAL FORMING

HIGH VELOCITY FORMINGHIGH VELOCITY FORMING

High velocity forming processes began to make High velocity forming processes began to make

their mark and grow in application in 1960.their mark and grow in application in 1960.

Requirements such as the introduction of super Requirements such as the introduction of super

tough alloys for space vehicles., supersonic aircraft tough alloys for space vehicles., supersonic aircraft

and the need for shaping incredibly small, thin and and the need for shaping incredibly small, thin and

brittle materials for electronic components helped brittle materials for electronic components helped

in the growth of high velocity forming processes. in the growth of high velocity forming processes.

In high velocity forming of metals, the metal is In high velocity forming of metals, the metal is

shaped in micro-seconds with pressures generated shaped in micro-seconds with pressures generated

by the sudden application of large amounts of by the sudden application of large amounts of

energy.energy.

HIGH VELOCITY FORMINGHIGH VELOCITY FORMING

Pressures needed for forming are Pressures needed for forming are

generated by :generated by :

1.1. Detonating explosives.Detonating explosives.

2.2. Releasing compressed gases.Releasing compressed gases.

3.3. Discharging powerful electrical sparks orDischarging powerful electrical sparks or

4.4. Electromagnetic energy.Electromagnetic energy.

Explosive formingExplosive forming

Electro-hydraulic forming.Electro-hydraulic forming.

Magnetic formingMagnetic forming

Pneumatic- mechanical high velocity forging..Pneumatic- mechanical high velocity forging..

TYPES OF HIGH VELOCITY TYPES OF HIGH VELOCITY FORMING PROCESSESFORMING PROCESSES

EXPLOSIVE EXPLOSIVE FORMINGFORMING

Explosive forming has evolved as one of the most dramatic Explosive forming has evolved as one of the most dramatic

of the new metalworking techniques. Explosive forming is of the new metalworking techniques. Explosive forming is

employed in Aerospace and aircraft industries and has been employed in Aerospace and aircraft industries and has been

successfully employed in the production of automotive-successfully employed in the production of automotive-

related components. Explosive Forming can be utilized to related components. Explosive Forming can be utilized to

form a wide variety of metals, from Aluminium to high form a wide variety of metals, from Aluminium to high

strength alloysstrength alloys

EXPLOSIVE FORMINGEXPLOSIVE FORMING

In this process the punch is replaced by an explosive charge. In this process the punch is replaced by an explosive charge.

The process derives its name from the fact that the energy The process derives its name from the fact that the energy

liberated due to the detonation of an explosive is used to form liberated due to the detonation of an explosive is used to form

the desired configuration. The charge used is very small, but the desired configuration. The charge used is very small, but

is capable of exerting tremendous forces on the work piece.is capable of exerting tremendous forces on the work piece.

In Explosive Forming chemical energy from the explosives is In Explosive Forming chemical energy from the explosives is

used to generate shock waves through a medium (mostly used to generate shock waves through a medium (mostly

water), which are directed to deform the work piece at very water), which are directed to deform the work piece at very

high velocities.high velocities.

EXPLOSIVE FORMINGEXPLOSIVE FORMING

Explosive forming makes use of the pressure wave Explosive forming makes use of the pressure wave

generated by an explosion in a fluid to force the generated by an explosion in a fluid to force the

material being formed against the walls of the material being formed against the walls of the

female die. The fluid has the effect of rounding off female die. The fluid has the effect of rounding off

the pressure pulse generated by the detonation. the pressure pulse generated by the detonation.

Methods of Explosive Methods of Explosive FormingForming

The explosives are used in many forms- rod, sheet, The explosives are used in many forms- rod, sheet,

granules, liquid, stick etc. Depending upon the placement granules, liquid, stick etc. Depending upon the placement

of the explosive (charge), the operations fall into two of the explosive (charge), the operations fall into two

categories :categories :

Stand-off operations.Stand-off operations.

Contact operations.Contact operations.

Methods of Explosive FormingMethods of Explosive Forming

Standoff MethodStandoff Method

In this method, the explosive charge is located at some In this method, the explosive charge is located at some

predetermined distance from the work piece and the energy is predetermined distance from the work piece and the energy is

transmitted through an intervening medium like air, oil, or transmitted through an intervening medium like air, oil, or

water. Peak pressure at the work piece may range from a few water. Peak pressure at the work piece may range from a few

thousand psi to several hundred thousand psi depending on thousand psi to several hundred thousand psi depending on

the parameters of the operation.the parameters of the operation.

METHODS OF METHODS OF EXPLOSIVE FORMINGEXPLOSIVE FORMING

Contact MethodContact Method

In this method, the explosive charge is held in In this method, the explosive charge is held in

direct contact with the work piece while the direct contact with the work piece while the

detonation is initiated. The detonation produces detonation is initiated. The detonation produces

interface pressures on the surface of the metal up to interface pressures on the surface of the metal up to

several million psi (35000 MPa).several million psi (35000 MPa).

METHODS OF EXPLOSIVE METHODS OF EXPLOSIVE FORMINGFORMING

WORKING PRINCIPLEWORKING PRINCIPLE

The system used for Standoff The system used for Standoff

operation consists of following operation consists of following

parts: -parts: -

1) An explosive charge1) An explosive charge

2) An energy transmitted 2) An energy transmitted

mediummedium

3) A die assembly3) A die assembly

4) The work piece.4) The work piece.

- - Figure 1Figure 1 shows an arrangement of Standoff Explosive shows an arrangement of Standoff Explosive

forming operation. The die assembly is put together on the forming operation. The die assembly is put together on the

bottom of the tank. Work piece is placed on the die and blank bottom of the tank. Work piece is placed on the die and blank

holder placed above. A vacuum is then created in the die cavity. holder placed above. A vacuum is then created in the die cavity.

The explosive charge is placed in position over the centre of the The explosive charge is placed in position over the centre of the

work piece. The explosive charge is suspended over the blank at work piece. The explosive charge is suspended over the blank at

a predetermined distance. The complete assembly is immersed in a predetermined distance. The complete assembly is immersed in

a tank of water. a tank of water.

- After the detonation of explosive, a pressure pulse of high - After the detonation of explosive, a pressure pulse of high

intensity is produced. A gas bubble is also produced which intensity is produced. A gas bubble is also produced which

expands spherically and then collapses until it vents at the expands spherically and then collapses until it vents at the

surface of the water. When the pressure pulse impinges against surface of the water. When the pressure pulse impinges against

the work piece, the metal is displaced into the die cavitythe work piece, the metal is displaced into the die cavity

WORKING PRINCIPLEWORKING PRINCIPLE

Explosives are substances that undergo rapid chemical Explosives are substances that undergo rapid chemical

reaction during which heat and large quantities of gaseous reaction during which heat and large quantities of gaseous

products are evolved.products are evolved.

Explosives are divide into two classes;Explosives are divide into two classes;

- Low Explosives in which the ammunition burns rapidly rather Low Explosives in which the ammunition burns rapidly rather

than exploding, hence pressure build up is not large.than exploding, hence pressure build up is not large.

- High Explosive which have a high rate of reaction with a large High Explosive which have a high rate of reaction with a large

pressure build up. pressure build up.

EXPLOSIVESEXPLOSIVES

Various explosives used are:Various explosives used are:

Solid (TNT-trinitro toluene)Solid (TNT-trinitro toluene)

Liquid (Nitroglycerine) Liquid (Nitroglycerine)

Gaseous (oxygen and acetylene mixtures). Gaseous (oxygen and acetylene mixtures).

EXPLOSIVESEXPLOSIVES

Low capital investment is required to adapt the process to Low capital investment is required to adapt the process to

production. production.

Large and expensive presses are not needed for forming. Large and expensive presses are not needed for forming.

Component is generally formed in one shot only.Component is generally formed in one shot only.

Only one die – either male or female is needed. For this reason Only one die – either male or female is needed. For this reason

tooling costs are greatly reduced.tooling costs are greatly reduced.

In general terms, the ultimate strength and yield strength are In general terms, the ultimate strength and yield strength are

improved by high explosive forming.improved by high explosive forming.

Large size parts unable to be handled successfully by Large size parts unable to be handled successfully by

conventional presses can be formed easily.conventional presses can be formed easily.

Advantages of Explosive FormingAdvantages of Explosive Forming Over Conventional formingOver Conventional forming

Personnel must be highly trained in the safe Personnel must be highly trained in the safe

handling of high explosives.handling of high explosives.

The technique has not been developed to the The technique has not been developed to the

stage where a part can always be formed on the stage where a part can always be formed on the

first shot.first shot.

The noise developed during forming and the The noise developed during forming and the

strict laws prohibiting the use of high explosives strict laws prohibiting the use of high explosives

in populated areas, usually make it necessary to in populated areas, usually make it necessary to

locate the facility away from populated areas. locate the facility away from populated areas.

This increase transportation and handling costs. This increase transportation and handling costs.

Disadvantages of Explosive Disadvantages of Explosive Forming Over Conventional Forming Over Conventional

formingforming

UsesUses

Blanking Coining Powder Blanking Coining Powder compacting compacting

Cutting Embossing Drawing Cutting Embossing Drawing Expanding Flanging Sizing Expanding Flanging Sizing

etc.etc.

ApplicationsApplications

Aerospace components. Aerospace components.

ELECTRO ELECTRO

HYDRAULIC HYDRAULIC

FORMING (EHF)FORMING (EHF)

The ability to generate high intensity shock waves by discharging stored The ability to generate high intensity shock waves by discharging stored

electrical energy across electrodes submerged in a liquid medium has been electrical energy across electrodes submerged in a liquid medium has been

recognized for a great many years. recognized for a great many years.

Spark discharge in a liquid was pointed out as a potential source of power Spark discharge in a liquid was pointed out as a potential source of power

in 1944. in 1944.

Basic research on under water condenser discharges was the subject of Basic research on under water condenser discharges was the subject of

several investigations in the early 1950’s.several investigations in the early 1950’s.

The first attempts to use electro hydraulic forming ( also called capacitor The first attempts to use electro hydraulic forming ( also called capacitor

discharge forming or spark forming ) process for forming metals were in discharge forming or spark forming ) process for forming metals were in

the United States in 1953 to punch holes in 1.5 mm steel plates. the United States in 1953 to punch holes in 1.5 mm steel plates.

INTRODUCTIONINTRODUCTION

PRINCIPLE OF OPERATIONPRINCIPLE OF OPERATION

Electro hydraulic forming involves the conversion of Electro hydraulic forming involves the conversion of

electrical energy to mechanical energy in a liquid medium. electrical energy to mechanical energy in a liquid medium.

Discharging of an electric spark in a liquid produces shock Discharging of an electric spark in a liquid produces shock

waves and pressures which can be used for metal forming. waves and pressures which can be used for metal forming.

As the energy produced is less than that produced in As the energy produced is less than that produced in

explosive forming, it is usually necessary to repeat the explosive forming, it is usually necessary to repeat the

operation several times to achieve the desired resultsoperation several times to achieve the desired results

METHODS TO CONVERT ELECTRICALMETHODS TO CONVERT ELECTRICAL

ENERGY INTO MECHANICAL ENERGY ENERGY INTO MECHANICAL ENERGY

Capacitor discharge through a gap :Capacitor discharge through a gap : Voltages of Voltages of

10,000 to 30,000 volts are generally used when the 10,000 to 30,000 volts are generally used when the

spark discharge method is utilized. This potential spark discharge method is utilized. This potential

difference will jump the air gap present between two difference will jump the air gap present between two

electrodes, submerged in the liquid.electrodes, submerged in the liquid.

METHODS TO CONVERT ELECTRICAL ENERGY METHODS TO CONVERT ELECTRICAL ENERGY

INTO MECHANICAL ENERGYINTO MECHANICAL ENERGY

Capacitor discharge through a wire :Capacitor discharge through a wire : provides better control than the provides better control than the

previous method because the path of the electrical discharge can be previous method because the path of the electrical discharge can be

positively determined and shaped, also a more efficient energy conversion positively determined and shaped, also a more efficient energy conversion

results. Moreover, with wire method, the use of lower potential difference is results. Moreover, with wire method, the use of lower potential difference is

possible; the wire will initiate a path across a wider gap than a specified possible; the wire will initiate a path across a wider gap than a specified

voltage will jump without the wire. A disadvantage of the wire method, voltage will jump without the wire. A disadvantage of the wire method,

however, is that a new wire is to be loaded after each shot for parts however, is that a new wire is to be loaded after each shot for parts

requiring multiple shots for reaching the desired results.requiring multiple shots for reaching the desired results.

In electrohydrauylic forming, electrical energy replaces the explosive used In electrohydrauylic forming, electrical energy replaces the explosive used

in explosive forming. High voltage electrical energy is discharged from a in explosive forming. High voltage electrical energy is discharged from a

capacitor bank (a device used to store electrical energy) into a thin wire or capacitor bank (a device used to store electrical energy) into a thin wire or

foil suspended between two electrodes. The unit is immersed in water. As foil suspended between two electrodes. The unit is immersed in water. As

the water vaporizes, the vapour products expand converting the electrical the water vaporizes, the vapour products expand converting the electrical

energy to hydraulic energy. The shock wave forms (or shapes) the metal energy to hydraulic energy. The shock wave forms (or shapes) the metal

against the die. against the die.

Since the energy produced for forming is less than that associated with Since the energy produced for forming is less than that associated with

explosives, it is usually necessary to repeat the operations several times to explosives, it is usually necessary to repeat the operations several times to

achieve the desiredachieve the desired resultsresults

ADVANTAGES OF EHF OVER ADVANTAGES OF EHF OVER CONVENTIONAL CONVENTIONAL

FORMING:FORMING: Many designs requiring standard operations have some Many designs requiring standard operations have some

peculiarity which is not within the capability of conventional peculiarity which is not within the capability of conventional

equipment, at least not without some special provision or equipment, at least not without some special provision or

tooling. Such works can be easily undertaking by EHF. tooling. Such works can be easily undertaking by EHF.

When EHF is used, the cost of tooling will almost always be less When EHF is used, the cost of tooling will almost always be less

than that for conventional equipment. than that for conventional equipment.

Large amounts of energy can be directed into isolated areas as Large amounts of energy can be directed into isolated areas as

required in some piercing operations. required in some piercing operations.

Reproducibility is another main advantage. Reproducibility is another main advantage.

DISADVANTAGES OF EHF DISADVANTAGES OF EHF

One of the most significant limitations of the process is the One of the most significant limitations of the process is the

energy rating of the capacitor bank itself, and the amount energy rating of the capacitor bank itself, and the amount

of energy which can be dumped by the triggering device is of energy which can be dumped by the triggering device is

another. another.

Materials having critical impact velocities below 30 meters Materials having critical impact velocities below 30 meters

per second are not practical for electohydraulic forming. per second are not practical for electohydraulic forming.

Neither is EHF of parts from materials having low Neither is EHF of parts from materials having low

ductility, such as the titanium alloys, likely to be successful. ductility, such as the titanium alloys, likely to be successful.

APPLICATIONS OF EHF:APPLICATIONS OF EHF:

A wide range of part sizes are producible by A wide range of part sizes are producible by

EHF, and most materials can be worked. EHF, and most materials can be worked.

The process is widely accepted in aerospace The process is widely accepted in aerospace

industries to accomplish bulging , forming, industries to accomplish bulging , forming,

beading, drawing, blanking and piercingbeading, drawing, blanking and piercing. .

MAGNETIC PULSE MAGNETIC PULSE FORMING(MPF)FORMING(MPF)

One of the earliest developments in producing a short One of the earliest developments in producing a short

duration, high intensity magnetic field was reported in 1924. A duration, high intensity magnetic field was reported in 1924. A

special storage battery was used as the energy source.special storage battery was used as the energy source.

Harvey and Brower, around 1958, demonstrated the Harvey and Brower, around 1958, demonstrated the

application of a magnetic system for forming metals. application of a magnetic system for forming metals.

In 1962, first magnetic commercial forming machine was In 1962, first magnetic commercial forming machine was

marketedmarketed

Using this technique, it is possible to apply to a metallic work Using this technique, it is possible to apply to a metallic work

piece a powerful, uniform magnetic pulse to swage and expand piece a powerful, uniform magnetic pulse to swage and expand

tubular forms, as well as to coin, shear and form flat sheets.tubular forms, as well as to coin, shear and form flat sheets.

INTRODUCTION

PRINCIPLE OF OPERATION:

A basic magnetic pulse metal A basic magnetic pulse metal

forming circuit consists of forming circuit consists of

-An energy storage -An energy storage

capacitor, capacitor,

-A switch-A switch

-A coil-A coil

-A power supply that -A power supply that

provides energy to charge a provides energy to charge a

capacitorcapacitor

FIGURE : Schematic illustration of the magnetic-pulse-forming process. The part is formed without physical contact without physical contact with any object

PRINCIPLE OF OPERATION:

An insulated induction coil is either An insulated induction coil is either

wrapped around, or placed within the wrapped around, or placed within the

work, depending on whether the work work, depending on whether the work

piece (metal) is required to be piece (metal) is required to be

squeezed inward or bulged outward. squeezed inward or bulged outward.

The coil is shaped to produce the The coil is shaped to produce the

desired shape in the work. desired shape in the work.

The power source is a capacitor bank. The power source is a capacitor bank.

Magnetic pulse forming machines Magnetic pulse forming machines

generate the very high currents generate the very high currents

required to produce the magnetic required to produce the magnetic

fields by discharging the capacitor fields by discharging the capacitor

bank through the coil.bank through the coil.

As a very high momentary currents are passed As a very high momentary currents are passed

through the coil an intense magnetic field is through the coil an intense magnetic field is

developed that causes the work to collapse, developed that causes the work to collapse,

compress, shrink or expand depending upon the compress, shrink or expand depending upon the

designs and placement of the coil. designs and placement of the coil.

Energy storage capacity and ability of the unit to Energy storage capacity and ability of the unit to

utilize that energy determines the size of the work utilize that energy determines the size of the work

that can be formed. Highly conductive metals can that can be formed. Highly conductive metals can

be formed easily. Non conductive or low be formed easily. Non conductive or low

conductivity materials can be formed if they are conductivity materials can be formed if they are

wrapped or coated with a high conductivity wrapped or coated with a high conductivity

auxiliary material. auxiliary material.

ADVANTAGES OF MPF OVER ADVANTAGES OF MPF OVER CONVENTIONAL FORMING:CONVENTIONAL FORMING:

The pressure is applied to the work piece through the The pressure is applied to the work piece through the

medium of a magnetic field without any physical medium of a magnetic field without any physical

contact.contact.

Since no static forces are involved in the process, Since no static forces are involved in the process,

relatively high structures may be used for the support relatively high structures may be used for the support

of dies.of dies.

Since there is no friction between the magnetic field Since there is no friction between the magnetic field

and the work piece, no lubricants are required and the and the work piece, no lubricants are required and the

process leaves no tool marks.process leaves no tool marks.

Machines can be designed for repetition rates of Machines can be designed for repetition rates of

hundreds of operations per minute.hundreds of operations per minute.

LIMITATIONS OF MPF :LIMITATIONS OF MPF :

The configuration of the work piece must be such The configuration of the work piece must be such

that the area to be formed constitutes a closed that the area to be formed constitutes a closed

loop, as in the case of rings, tubes, circular areas loop, as in the case of rings, tubes, circular areas

on flat work pieces etc., thus permitting the on flat work pieces etc., thus permitting the

induced currents to flow. Slits interrupting the induced currents to flow. Slits interrupting the

paths of the induced currents have a detrimental paths of the induced currents have a detrimental

effect on MPF process. effect on MPF process.

It is not possible to apply high pressures in an It is not possible to apply high pressures in an

arbitrarily chosen area while applying a low arbitrarily chosen area while applying a low

pressure in a closely adjacent area. pressure in a closely adjacent area.

APPLICATIONS OF MPF :APPLICATIONS OF MPF :

The magnetic pulse forming process has been primarily applied in the The magnetic pulse forming process has been primarily applied in the

forming of excellent conductors, such as aluminum, copper, brass and forming of excellent conductors, such as aluminum, copper, brass and

low carbon steel. It has also been used effectively to form poor low carbon steel. It has also been used effectively to form poor

conductors such as stainless steel for use with highly conductive sheaths. conductors such as stainless steel for use with highly conductive sheaths.

MPF is used widely to expand, compress or form tubular shapes and MPF is used widely to expand, compress or form tubular shapes and

has also been used effectively to form conical, ellipsoidal and flat work has also been used effectively to form conical, ellipsoidal and flat work

pieces and assembly operations in a single step. The method is also used pieces and assembly operations in a single step. The method is also used

for piercing, shearing, embossing, cupping, sizing, banding etc. for piercing, shearing, embossing, cupping, sizing, banding etc.

Tubular members can be joined to end fittings by magnetic swaging. Tubular members can be joined to end fittings by magnetic swaging.

PNEUMATIC PNEUMATIC MECHANICAL MECHANICAL

HIGH VELOCITY HIGH VELOCITY FORGINGFORGING

Just as a turret lathe can be set up to machine hundreds of Just as a turret lathe can be set up to machine hundreds of

identical parts, so also pneumatic mechanical, high velocity identical parts, so also pneumatic mechanical, high velocity

forging machine can be set up to produce hundreds of forging machine can be set up to produce hundreds of

identical forging without depending on the skill of the identical forging without depending on the skill of the

operator. operator.

High velocity forging is a closed die hot or cold forging High velocity forging is a closed die hot or cold forging

process which unlike conventional forging, deforms work process which unlike conventional forging, deforms work

metal at unusually high velocities. Identify, the final metal at unusually high velocities. Identify, the final

configurations of the forging is developed in one blow, or at configurations of the forging is developed in one blow, or at

most, in a few blows. most, in a few blows.

High velocity forging can be used for hot forging of the parts High velocity forging can be used for hot forging of the parts

of the same general shapes as those produced in of the same general shapes as those produced in

conventional forging hammers and presses. conventional forging hammers and presses.

COMPARASION WITH COMPARASION WITH CONVENTIONAL FORGINGCONVENTIONAL FORGING

The forces developed in high velocity forging are many The forces developed in high velocity forging are many

times more powerful and are sufficient to shape hard to times more powerful and are sufficient to shape hard to

work materials. work materials.

High velocity forging, single blow, hammers require less High velocity forging, single blow, hammers require less

moving weight than do conventional hammer to achieve moving weight than do conventional hammer to achieve

the same impact energy per blow.the same impact energy per blow.

This machine also requires considerably less space than This machine also requires considerably less space than

the conventional forging press. the conventional forging press.

COMPARASION WITH COMPARASION WITH CONVENTIONAL FORGINGCONVENTIONAL FORGING

Pneumatic-mechanical forging machines Pneumatic-mechanical forging machines

use:use:

the energy stored in a compressed gas the energy stored in a compressed gas

e.g. nitrogen e.g. nitrogen

the energy released from burning fuel the energy released from burning fuel

(petrol) oxidizer mixture to accelerate a (petrol) oxidizer mixture to accelerate a

ram to a high velocity for accomplishing ram to a high velocity for accomplishing

a deformation stroke or hammer.a deformation stroke or hammer.

PRINCIPLE OF OPERATION:PRINCIPLE OF OPERATION:

In the gas operated pneumatic mechanical machines, energy in obtained by expandingIn the gas operated pneumatic mechanical machines, energy in obtained by expanding

A High pressure gas to drive a piston down a cylinder. In most machines, theA High pressure gas to drive a piston down a cylinder. In most machines, the

pressurized gas is stored and made to act on the top of the ram with the help of quickpressurized gas is stored and made to act on the top of the ram with the help of quick

release mechanism for rapid acceleration of the ram. The gas accelerates the ram torelease mechanism for rapid acceleration of the ram. The gas accelerates the ram to

high speeds. During the process there is a very rapid build up on the work piece.high speeds. During the process there is a very rapid build up on the work piece.

Subsequent to each hammer blow the gas is recompressed. The original quantity ofSubsequent to each hammer blow the gas is recompressed. The original quantity of

gas is used time after time or no loss, resulting in very low operating cost. gas is used time after time or no loss, resulting in very low operating cost.

Repeatability is an important feature.Repeatability is an important feature.


There is an inner frame and an outer frame within which the There is an inner frame and an outer frame within which the

inner frame is free to move vertically. As the trigger gas steel inner frame is free to move vertically. As the trigger gas steel

is opened, high pressure gas from the firing chamber acts from is opened, high pressure gas from the firing chamber acts from

the top face of the ram and forces the ram and the upper die the top face of the ram and forces the ram and the upper die

downward. downward.

Reaction to the downward Acceleration of the ram raises the Reaction to the downward Acceleration of the ram raises the

inner frame and lower die. The machine is made ready for the inner frame and lower die. The machine is made ready for the

next blow by means of hydraulic jacks that elevate the ram until next blow by means of hydraulic jacks that elevate the ram until

the trigger gas seal between the upper surface of the firing the trigger gas seal between the upper surface of the firing

chamber and the ram top is re established. chamber and the ram top is re established.

The machine uses air springs and thus the shock is not The machine uses air springs and thus the shock is not

transmitted to the floor. Therefore, a special foundation is not transmitted to the floor. Therefore, a special foundation is not

needed, and the ,machine can be placed directly on the factory needed, and the ,machine can be placed directly on the factory

floor. floor.


ADVANTAGES OF PNEUMATIC-MECHANICAL FORGING :

• Metals difficult to forge by other methods can be forged successfully.

• Complex parts can be forged in one blow.

• Forging are made to size or within a minimum of machining allowance.

• Dimensional accuracy, surface details and often, surface finish are improved.

• Draft allowances can be reduced.

• Severe deformation results in greater gain refinement in some metals.

• Deep, thin sections can be forged.

DISADVANTAGES OF PNEUMATIC-MECHANICAL FORGING :

1. Process generally is limited to symmetrical parts.

2. Sharp corners and small radii can not be forged without causing

undue die wear.

3. The production rate is about the same as in hammer or hydraulic

press forging, but slower than in mechanical press forging.

4. Part size is limited to about 10 kg fore carbon steel forging, and to

lesser weights for forging made of stainless steel or heat resisting

alloys.

APPLICATIONS OF PNEUMATIC-MECHANICAL FORGING :

1. Symmetrical or concentric forging such as gears

and wheels.

2. Parts with thin webs and high rib height to width

ratios.

3. Forging of super alloys, refractory alloys, as cast

materials, low alloy steels, aluminum alloys,

titanium alloys, stainless steels etc.

4. Turbine blades and turbine wheels.

5. Valve bodies.

6. Rifle parts.

7. Missile components.

8. Housings for electronic devices.

9. Engine housings.

10.Rocket nozzle inserts, etc.

ECONOMIC CHARACTERISTICS

When making a cost comparison to aid in

selecting in between one of these special

processes and a conventional one, or when

choosing between two different special

processes, each of which appears capable of

accomplishing the necessary forming, the

engineer is advised therefore, to contact

manufacturers of the respective equipment to

obtain the most current information available.

ECONOMIC CHARACTERISTICSExperience indicates that the HVF processes are

generally more useful in the production of

smaller quantities of parts. For the production of

small number of parts, the unit cost makes a

HVF operation more favorable because of the

generally lower initial cost of tooling, capital

equipment etc. However as the number of parts

is increased and the unit cost for the

conventional method becomes the lower .In

industries that produce extremely large numbers

of parts, such as the stamping industry, are not

economically feasible for most HVF techniques.

CAPABILITY OF HVF PROCRSSESCharacteristics Characteristics Electro hydraulic Forming

High Explosive(stand-off)Bridge wire Spark discharge

Metal working operations

Tube bulging, drawing sizing, flanging, coining , blanking, stretching

Tube bulging, sizing, flanging, expanding, coining , blanking, stretching, embossing

Draw forming, sizing, flanging, expanding, coining ,blanking,stretching,embossing,beading,joining

Size limitations 6.1542mm diameter or larger

6.1542mm diameter or larger Limited only by available blank size

Shape complexity

Complex surface and shapes, especially tubular

Complex surface and shapes, especially tubular

Small and intricate, large and simple

Capital investment

Moderate Moderate low

Tooling cost low low low

Labor cost moderate moderate moderate

Production rate 360 parts per hr depending on part and equipment

360 parts per hr depending on part and equipment

0.5-4 parts per hr or less depending on part and facility

CAPABILITY OF HVF PROCRSSESCharacteristics Characteristics Electro hydraulic Forming High

Explosive(stand-off)Bridge wire Spark discharge

Cycle time Long medium medium

Energy costs low low high

Safety considerations Equipment interlocks, high voltage safety practices, trained personnel

Equipment interlocks, high voltage safety practices, trained personnel

Trained personnel

Method of energy release

Vaporization of wires Vaporization of medium Chemical detonation

Pressure wave velocity

20,000(6096)

20,000 (6096)

4,000 to 25,000(1219-7620)

Pressure wave duration

microseconds microseconds microseconds

Energy range(KJ) 20,000 to 175,000(27 to 237)

10,000 to 110,000(13.5 to 150 )

100,000 to 2,000.000(136-2712) per lb of explosive, up to 100 lb 45 kg detonator

Work-piece deformation velocity(m/s)

50 to 700 (15-213)

50 to 700 (15-213)

60 to 400 (18 to 122)

Energy transfer medium

Water or other suitable liquid Water or other suitable liquid Water, elastomers sand, molten salts

Characteristics Characteristics High Explosive(direct contact)

Electromagnetic Mechanical-Pneumatic forging

Metal working operations

draw forming, sizing, flanging, expanding, coining , blanking, stretch forming,embossing,beading, cutting, powder compacting, joining,

Hardening,welding, perforating, cladding, powder compacting

Hot, warm, cold forming water compacting, powder forging, cropping, blanking, piercing, coining

Size limitations Part size not limiting 0.1-72(2.5-1830mm) diam. and larger in some operations

Up to 24 (610mm) diam. larger on future machines

Shape complexity Simple shapes Compound surfaces, corrective forming on large complex shapes

Complex shapes thin forged sections

Capital investment low Moderate to high moderate

Tooling cost None to low High if work coil is regarded as part of tooling

moderate

Labor cost moderate Moderate to low moderate

Production rate 0.5-4 parts per hr or less depending on part and facility

Up to 12,000 parts per hr for simple parts and automated transfer equipment

60 to 100 parts per hr with automatic equipment, depending upon part complexity

CAPABILITY OF HVF PROCRSSES

ECONOMIC CHARACTERISTICSCharacteristics Characteristics High Explosive(direct

contact)Electromagnetic Mechanical-

Pneumatic forging

Cycle time medium Medium to short long

Energy costs high low moderate

Safety considerations

Trained personnel Equipment interlocks, high voltage safety practices, trained personnel

Guards and shields, trained personnel

Method of energy release

Chemical detonation Expanding magnetic fieldExpanding magnetic field Quick-release valveQuick-release valve

Pressure wave velocity

4,000 to 25,000(1219-7620)

Not applicableNot applicable Not applicableNot applicable

Pressure wave duration

Microseconds Microseconds Microseconds Microseconds Microseconds

Energy range(KJ) 0.5-8 psf high explosive 0-175,00(0-237)0-175,00(0-237) Up to Up to 400,000(542)400,000(542)

Work-piece deformation velocity(m/s)

Not applicable 50-1000(15-305)50-1000(15-305) 50-700(15-213)50-700(15-213)

Energy transfer medium

Direct contact or buffer material

Magnetic field (to be Magnetic field (to be operated in vacuum)operated in vacuum)

High – velocity High – velocity ramram

REFERENCES :REFERENCES :““Production Technology” by O.P.Khanna, Dhanpat Rai Publishers,1998.Production Technology” by O.P.Khanna, Dhanpat Rai Publishers,1998.

Materials and Processes in Manufacturing” by DeGarmo, Black & Kosher, Prentice-Materials and Processes in Manufacturing” by DeGarmo, Black & Kosher, Prentice-

Hall Publishers, 1997Hall Publishers, 1997

archive.metalformingmagazine.com/1997/01/7mfjan5.htm archive.metalformingmagazine.com/1997/01/7mfjan5.htm

www.metalwebnews.com/howto/explosive-forming/explosive-forming.html www.metalwebnews.com/howto/explosive-forming/explosive-forming.html

en.wikipedia.org/wiki/Electromagnetic_formingen.wikipedia.org/wiki/Electromagnetic_forming

www.fsb.hr/deformiranje/Presentation_Wentzel_TNO_PML_Rijswijk.pdf

web.mit.edu/3.082/www/team1_s03/presentation4.10.ppt web.mit.edu/3.082/www/team1_s03/presentation4.10.ppt

www.engineershandbook.com/MfgMethods/ehforming.htm www.engineershandbook.com/MfgMethods/ehforming.htm

en.wikipedia.org/wiki/Electromagnetic_forming en.wikipedia.org/wiki/Electromagnetic_forming

www.iap.com/metalfor.html www.iap.com/metalfor.html

high velocity forming

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