Final print report

Powder Metallurgy Process Standardization of Synchronizer Hub 2013-2014

Department of Mechanical Engineering, PCCOE 1

1. INTRODUCTION:-

1.1 Introduction to Powder Metallurgy

Powder metallurgy is a process of making components from metallic powders. Initially, it

was used to replace castings for metals which were difficult to melt because of high

melting point. The development of technique made it possible to produce a product

economically, and today it occupies an important place in the field of metal process. The

number of material products made by powder metallurgy is increasing and includes

tungsten filaments of lamps, contact points. Self-lubricating bearings and cemented

carbides for cutting tools.

1.2 Characteristics of Metal Powder:-

The performance of metal powders during processing and the properties of powder

metallurgy are dependent upon the characteristics of the metal powders that are used.

Following are the important characteristics of metal powders.

(1) Particle shape

(2) Particle size

(3) Particle size distribution

(4) Flow rate

(5) Compressibility

(6) Apparent density

(7) Purity

1.2.1 Particle Shape:-

The particle shape depends largely on the method of powder manufacture. The shape may

be special nodular, irregular, angular, and dendritic. The particle shape influences the flow

characteristics of powders. Special particles have excellent sintering properties. However,



irregular shaped particles are good at green strength because they will interlock on

compacting.

1.2.2 Particle Size:-

The particle size influences the control of porosity, compressibility and amount of

shrinkage. It is determined by passing the powder through standard sieves or by

microscopic measurement.

1.2.3 Particle Size Distribution:-

It is specified in term of a sieve analysis, the amount of powder passing through

100, 200 etc., mess sieves. Different sieves are arranged one below the other as per their

mesh numbers, the coarsest being on the top and the entire stack of sieves is vibrated for

15 minutes by a standard shaking machine which gives circular and translator motions to

the screens. After this, the amount of powder retained on each sieve is accurately

measured. From these weights, size and size distribution can be found out. Size

distribution is expressed by weight fraction of powder retained on each sieve. Sieve

distribution method gives fairly accurate result when the powder is in the size range of 44

to 840 microns. Particle size distribution influences the packing of powder and its

behaviour during moulding and sintering.

1.2.4 Flow Rate:-

It is the ability of powder to flow readily and confirm to the mould cavity. It determines

the rate of production and economy. An apparatus used to determine flow rate is called

flow meter. Flow rate depends on particle size, shape, distribution, amount of absorbed

gases, amount of moisture, and coefficient of friction. In general, fine or irregular particles

have poor flowability and coarse or spherical particles have better flowability. Flow rate

increases with decreased particle irregularity and increased particle size. For rapid filling

of the die and uniform density of the cold compact, the powder must have high flowability.

There is a close relationship between apparent density and flowability and hence it is very



difficult to vary any one without altering the other. Flow rate, apparent density and tap

density are important properties because they affect transporting and pressing

characteristics of powders.

1.2.5 Compressibility:-

It is defined as volume of initial powder (powder loosely filled in cavity)to the volume of

compact part. It depends on particle size, distribution and shape. It is also defined as the

powders ability to undergo deformation under the applied pressure and is measured by

many ways as below:

A) Ratio of green density of compact to the apparent density of the powder.

B) Ratio of the height of the uncompacted powder in the die to the height of the

pressed compact.

C) Ratio of the volume of powder poured into the die to the volume of the pressed

compact(i.e. compression ratio)

1.2.6 Apparent Density:-

It depends on particle size and is defined as the ratio of volume to weight of loosely filled

mixture. Thus it includes internal pores but excludes external pores. It is governed by

chemical composition, particle shape, size distribution, method of manufacture of metal

powders and surface conditions. This strongly influences the pressing characteristics. The

lower the apparent density, the longer will be the compression stroke and deeper dies will

be required to produce a compact of given thickness and density.

1.2.7 Purity:-

Metal powders should be free from impurities as the impurities reduce the life of dies and

effect sintering process. The oxides and the gaseous impurities can be removed from the

part during sintering by use of reducing atmosphere.



1.3 Basic Steps of The Process:-

The manufacturing of parts by powder metallurgy process involves the following steps:

(1) Manufacturing of metal powders

(2) Blending and mixing of powders

(3) Compacting

(4) Sintering

(5) Finishing operations

Fig. 1.1 Basic Steps of the Process

1.3.1 Manufacturing of Metal Powders:-

There are various methods available for the production of powders, depending upon the

type and nature of metal. Some of the important processes are:

1. Atomization

2. Machining

3. Crushing and Milling

4. Reduction

5. Electrolytic Deposition

6. Shotting

7. Condensation



1.3.1.1 Atomization:-

In this method molten metal is forced through a small orifice and is disintegrated by a

powerful jet of compressed air, inert gas or water jet. These small particles are then

allowed to solidify. These are generally spherical in shape. Automation is used mostly for

low melting point metals/alloy such as brass, bronze, zinc, tin, lead and aluminium

powders.

1.3.1.2 Machining:-

In this method first chips are produced by filing, turning etc. and subsequently pulverised

by crushing and milling. The powders produced by this method are coarse in size and

irregular in shape. Hence, this method is used for special cases such as production of

magnesium powder.

1.3.1.3 Crushing and Milling:-

These methods are used for brittle materials. Jaw crushers, stamping mills, ball mills are

used to breakdown the metals by crushing and impact. In earlier stages of powder

preparation gyratory crushers are used to crush brittle metals. For fine powder, the metal

particles are fractured by impact. A ball mill is a horizontal barrel shaped container

holding a quantity of balls which are free to tumble about as the container rotates, crushes

and abrade the powder particles that are introduced into the container. Any type of material

can be powdered by milling method. However, it is widely used for carbide-metal mixtures

and cermet’s for particle size reduction and blending. All the above three methods have

low rates of powder production. The particle shape is neither perfectly irregular nor

spherical but is intermediate to the above two. This is suitable for the manufacture of large

number of components by P/M. The powders obtained from these methods are in work-

hardened condition and hence require annealing heat treatment prior to their compaction.



1.3.1.4 Reduction:-

Pure metal is obtained by reducing its oxide with a suitable reducing gas at an elevated

temperature (below the melting point) in a controlled furnace. The reduced product is then

crushed and milled to a powder. Sponge iron powder is produced this way

Fe3O4 + 4C = 3Fe + 4CO

Fe3O4 + 4CO = 3Fe + 4CO2

Copper powder by

Cu2O + H2 = 2Cu + H2O

Tungsten, Molybdenum, Ni and Cobalt are made by the method. The usual reducing

agents employed are carbon, hydrogen, ammonia and carbon monoxide. In few cases,

some metals have been used as reducing agents to reduce the other metal oxides; e.g. Cr

powder is produced by reduction of chromium oxide with Mg, and Zr powder by reduction

of Zirconium oxide with Ca or Mg. The powders obtained by this method are fine and the

shape of particles is irregular.

1.3.1.5 Electrolytic Deposition:-

This method is commonly used for producing iron and copper powders. This process is

similar to electroplating. For making copper powder, copper plates are placed as anodes in

the tank of electrolyte, where as the aluminium plates are placed into electrolyte to act as

anode. When D. C. current is passed through the electrolyte, the copper get deposited on

cathode. The cathode plates are taken out from electrolyte tank and the deposited powder

is scrapped off. The powder is washed, dried and pulverised to produce powder of the

desired grain size. The powder is further subjected to heat treatment to remove work

hardness effect. The cost of manufacturing is high.



1.3.1.6 Shotting:-

In this method, the molten metal is poured through a sieve or orifice and is cooled by

dropping into water. This produces spherical particles of large size. This method is

commonly used for metals of law melting points. The size and character of the powder

depends on the temperature of molten metal, size of openings in the screen and frequency

of vibrations of the screen.

1.3.1.7 Condensation:-

In this method, metals are boiled to produce metal vapours and then condensed to obtain

metal powders. This process is applied to volatile metals such as zinc, magnesium and

cadmium. Large quantities of Zn, Mg and Cd powders are manufactured by this method.

Due cares must be taken to avoid the formation of metal oxides.

1.3.2 Blending and Mixing of Powders:-

Powder blending and mixing of the powders are essential for uniformity of the product.

Lubricants are added to the blending of powders before mixing. The function of lubricant

is to minimise the wear, to reduce friction. Different powder in correct proportions are

thoroughly mixed either wet or in a ball mill.

1.3.3 Compacting:-

The main purpose of compacting is converting loose powder into a green compact of

accurate shape and size. The following methods are adopted for compacting:

1. Pressing

2. Centrifugal compacting

3. Slip casting

4. Extrusion

5. Gravity sintering

6. Rolling



7. Isostatic moulding

8. Explosive moulding

1.3.3.1 Pressing:-

The metal powders are placed in a die cavity and compressed to form a component shaped

to the contour of the die as illustrated in Fig. The pressure used for producing green

compact of the component vary from 80 Mpa to 1400 Mpa, depending upon the material

and the characteristics of the powder used. Mechanical presses are used for compacting

objects at low pressure. Hydraulic presses are for compacting objects at high pressure.

1.3.3.2 Centrifugal Compacting:-

In this method, the moulder after it is filled with powder is centrifugal to get a compact of

high and uniform density at a pressure of 3 Mpa. This method is employed for heavy

metals such as tungsten carbide.

1.3.3.3 Slip Casting:-

In this method, the powder is converted into slurry with water and poured into the mould

made of plaster of paris. The liquid in the slurry is gradually absorbed by the mould

leaving the solid compact within the mould. The mould may be vibrated to increase the

density of the compact. This technique is used for materials that are relatively

incompressible by conventional die compaction. The main drawback of this process is

relatively slower process because it takes larger time for the fluid to be absorbed by the

method.



1.3.3.4 Extrusion:-

This method is employed to produce the components with high density. Both cold and hot

extrusion processes are for compacting specific materials. In cold extrusion, the metal

powder is mixed with binder and this mixture is compressed into billet. The binder is

removed before or during sintering. The billet is charged into a container and then forced

through the die by means of ram. The cross-section of product depends on the opening of

the die. Cold extrusion process is used for cemented carbide drills and cutters of ram. The

cross-section of products depends on the opening of the die. Cold extrusion process is used

for cemented carbide drills and cutters. In the hot extrusion, the powder is compacted into

billet and is heated to extruding temperature in non-oxidising atmosphere. The billet is

placed in the container and extruded through a die. This method is used for refractive

barium and nuclear solid materials.

1.3.3.5 Gravity Sintering:-

This process is used for making sheets for controlled porosity. In this process the powder

is poured on ceramic tray to form an uniform layer and is then sintered up to48 hours in

ammonia gas at high temperature. The sheets are then rolled to desired thickness. Porous

sheet of stainless steel are made by this process and popularly used for fitters.

1.3.3.6 Rolling:-

This method is used for making continuous strips and rods having controlled porosity with

uniform mechanical properties. In this method, the metal powder is fed between two rolls

which compress and interlock the powder particles to form a sheet of sufficient strength as

shown in Fig. 4.3. It then situated, rerolled and heat treated if necessary. The metals that

can be rolled are Cu, Brass, Bronze, Ni, Stainless steel and Monel.



1.3.3.7 Isostatic Moulding:-

In this method, metal powder is placed in an elastic mould which is subjected to gas

pressure in the range of 65-650 Mpa from all sides. After pressing the compact is removed

from gas chamber. If the fluid is used as press medium then it is called as hydrostatic

pressing. The advantages of this method are: uniform strength in all directions, higher

green compact strength and low equipment cost. This method is used for tungsten,

molybdenum, niobium etc.

1.3.3.8 Explosive Compacting:-

In this method, the pressure generated by an explosive is used to compact the metal

powder. Metal powder is placed in water proof bags which are immersed in water

container cylinder of high wall thickness. Due to sudden deterioration of the charge at the

end of the cylinder, the pressure of the cylinder increase. This pressure is used to press the

metal powder to form green compact.

1.3.4 Sintering:-

Sintering involves heating of the green compact at high temperatures in a controlled

atmosphere [reducing atmosphere which protects oxidation of metal powders]. Sintering

increases the bond between the particles and therefore strengthens the powder metal

compact. Sintering temperature and time is usually 0.6 to 0.8 times the melting point of the

powder. In case of mixed powders of different melting temperature, the sintering

temperature will usually be above the melting point of one of the minor constituent and

other powders remain in solid state. The important factors governing sintering are

temperature, time and atmosphere. The sintering temperature and time of sintering for

different metal powders are given below:



Hot pressing:-

Hot pressing involves applying pressure and temperature simultaneously, so that the

compacting and sintering of the powder takes place at the same time in a die. Its

application is limited and can be used for compacting. Fe and Brass powders at much

lower pressure than conventional pressing and sintering operations.

1.3.5 Finishing Operations:-

These are secondary operations intended to provide dimensional tolerances, physical and

better surface finish. They are:

1. Sizing

2. Coining

3. Machining

4. Impregnation

5. Infiltration

6. Heat treatment

7. Plating

1.3.5.1 Sizing:-

It is repressing the sintered component in the die to achieve the required accuracy.

1.3.5.2 Coining:-

It is repressing the sintered components in the die to increase density and to give additional

strength.

1.3.5.3 Machining:-

Machining operation is carried out on sintered part to provide under cuts, holes, threads

etc. which can not be removed on the part in the powder metallurgy process.



1.3.5.4 Impregnation:-

It is filling of oil, grease or other lubricants in a sintered component such as bearing.

1.3.5.5 Infiltration:-

It is filling of pores of sintered product with molten metal to improve physical properties.

1.3.5.6 Heat Treatment:-

The Process of heating and cooling sintered parts are to improve

(i) Wear Resistance

(ii) Grain Structure

(iii) Strength

The following heat treatment process are used to the parts made by powder metallurgy:

1. Stress relieving

2. Carburising

3. Nitriding

4. Induction Hardening

1.3.5.7 Plating:-

Plating is carried out in order to:

1. Import a pleasing appearance (Cr plating)

2. Protect from corrosion (Ni plating)

3. Improve electrical conductivity (Cu and Ag plating)

1.4 Design Considerations For Powder Metallurgy Parts:-

In designing of powder metallurgy parts, the following are the some of tooling and

pressing considerations.



1) Side holes and side ways are not possible to achieve during pressing and must be made

by secondary machining operations.

2) Threads, knurling and other similar shapes cannot be formed compacting. They should

be produced by machining.

3) Abrupt changes in section thickness and narrow and deeper sections should be avoided

as far as practicable.

4) It is recommended that sharp corners be avoided wherever possible. Fillets with

generous radii are desirable.

5) Chambers can be made.

6) Under cuts that are perpendicular to the pressing direction can not be made, since they

prevent the part ejection.

1.5 Advantages Of Powder Metallurgy:-

1) Although the cost of making powder is high there is no loss of material. The

components produced are clean, bright and ready for use.

2) The greatest advantage of this process is the control of the composition of the product.

3) Components can be produced with good surface finish and close tolerance.

4) High production rates.

5) Complex shapes can be produced.

6) Wide range of properties such as density, porosity and particle size can be obtained for

particular applications.

7) There is usually no need for subsequent machining or finishing operations.

8) This process facilitates mixing of both metallic and non-metallic powders to give

products of special characteristics.

9) Porous parts can be produced that could not be made any other way.

10) Impossible parts (cutting tool bits) can be produced.

11) Highly qualified or skilled labour is not required.



1.6 Limitation of Powder Metallurgy:-

1) The Metal powders and the equipment used are very costly.

2) Storing of powders offer great difficulties because of possibility of fire and explosion

hazards.

3) Parts manufactured by this process have poor ductility.

4) Sintering of low melting point powders like lead, zinc, tin etc., offer serious difficulties.

1.7 Applications of Powder Metallurgy:-

Powder metallurgy techniques are used for making large number of components. Some of

the applications are as follows:

1.7.1 Self-Lubricating Bearing and Filters:-

Porous bronze bearings are made by mixing copper and tin powder in correct proportions,

cold pressed to the desired shape and then sintered. These bearings soak up considerable

quantity of oil. Hence during service, these bearings produce a constant supply of lubricant

to the surface due to capillary action. These are used where lubrication is not possible.

Porous filters can be manufactured and are used to remove, external undesirable materials

from liquids and gases.

1.7.2 Friction Materials:-

These are made by powder metallurgy. Clutch liners and Brake bands are the example of

friction materials.

1.7.3 Gears and Pump Rotors:-

Gears and pump rotor for automobile oil pumps are manufactured by powder metallurgy.

Iron powder is mixed with graphite, compacted under a pressure of 40 kg/cm and sintered



in an electric furnace with an atmosphere and hydrocarbon gas. These are impregnated

with oil.

1.7.4 Refractor Materials:-

Metals with high melting points are termed as refractory metals. These basically include

four metals tungsten, molybdenum, tantalum and niobium. Refractory metals as well as

their alloys are manufactured by powder metallurgy. The application are not limited to

lamp filaments and heating elements, they also include space technology and the heavy

metal used in radioactive shielding.

1.7.5 Electrical Contacts and Electrodes:-

Electrical contacts and resistance welding electrodes are made by powder metallurgy. A

combination of copper, silver and a refractory metal like tungsten, molybdenum and nickel

provides the required characteristics like wear resistant, refractory property and electrical

conductivity.

1.7.6 Magnet Materials:-

Soft and permanent magnets are manufactured by this process. Soft magnets are made of

iron, iron-silicon and iron-nickle alloys. These are used in D.C. motors, or generators as

armatures and in measuring instruments. Permanent magnets known as Alnico which is a

mixture of nickle, aluminium, cobalt, copper and iron are manufactured by this technique.

1.7.7 Cemented Carbides:-

These are very important products of powder metallurgy and find wide applications as

cutting tools, wire drawing dies and deep drawing dies. These consist of carbides of

tungsten, tantalum, titanium and molybdenum. The actual proportions of various carbides

depend upon its applications, either cobalt or nickle is used as the bonding agent while

sintering.



2. LITERATURE SURVEY

2.1 Synchronizer Hub

The transmission system is one of the main parts that determines the behaviour, power and

fuel economy of a vehicle. Transmission performance is usually related to gear efficiency,

gear noise and gear shift comfort during gear change. Synchronizer mechanisms allow

gear changing in a smooth way, noiseless and without vibrations, both for the durability of

the transmission and the comfort for the users. As a consequence, it is aimed an

improvement of the dynamic shift quality, by reducing shifting time and effort, especially

in heavy truck applications. Synchronization processes are used in order to get a smooth

gear shift and a good shift feel, by reducing the time of synchronization inside the gearbox

and the load required at the driver's hand. They prevent transmission gears from shocking,

reduce noise and gear wearing and make the driver feel comfortable inside the cabin.

Fig. 2.1 Synchronizer hub



2.2 Synchronizer Components:-

The synchronizer assembly includes:

Fig. 2.2 Exploded view of synchronizer assembly

2.2.1 Synchronizer hub:-

Is rigidly connected by a spline to the rotating shaft(input or output shaft).

2.2.2 Sliding sleeve / Gear shift sleeve / Synchronizer sleeve / Coupling sleeve:-

Has a groove on the outer periphery for the gear shift fork. Includes internal splines that

are in constant mesh with the synchro hub external splines, so it is only axially movable

from a neutral position to an engaged position.Both parts and the main shaft work as a

single unit hence they move at the same angular speed.

2.2.3 Synchronizer ring / Blocking ring / Balk ring / Friction ring:-

The external teeth interlock with the internal teeth of the sliding sleeve. It has a conical

surface that is fitted with the conical surface of the clutch body ring. Its purpose is to

produce the friction torque needed to synchronize the input and output shafts. The cone

surfaces are provided with thread or groove patterns and axial grooves in order to either

prevent or break the hydrodynamic oil film and minimize force increase.



2.2.4 Clutch gear with cone:-

Matches the speed of the gear with the speed of the synchro hub. It is either press fitted or

laser welded with the gear wheel. The external teeth with chamfer on both sides of the

teeth interlock with the chamfer on the internal teeth of shift sleeve.

2.2.5 Gear wheel:-

Normally is connected to the main shaft by a needle bearing for relative rotation between

both components and secured against axial movement relative to the shaft. It can also be

mounted on the shaft with a very smooth surface and proper lubrication (hydrodynamic

bearing).

2.2.6 Strut detent / Centring mechanism / Strut key:-

Spring loaded ball or roller fixed in a cage. Is arranged on the circumference of the

synchronizer body, positioned between the groove in synchro hub and the inner groove in

shift sleeve. Therefore can integrally rotate with the synchro hub and is axially movable

with the shift sleeve. This component is used for pre-synchronization; it means that

generates the load on synchro ring to perform the synchronization process. In addition,

maintains the sliding sleeve in a central position on the hub between both gear wheels and

below a limit axial force. Often, the synchronizers are composed by three of these

elements arranged at 120°. In the case of large synchronizers, there are four elements

arranged at 90°.



2.2 The Synchronization Process:-

Following figures shows the synchronization process when it is in operation.

Fig.2.3 Neutral Fig.2.4 Pre-Synchronization

Fig.2.5 Synchronization Fig.2.6Blocking Release

Fig.2.7Engagement Fig.2.8 Gear shifted



3. CHALLENGES:-

1) Complexity in Geometry.

2) Dimensional behaviour.

-Radial dimensions over size/under size.

-Axial dimensions over size/under size.

From above we have chosen to work on only radial dimensions because axial dimensions

can be easily controlled up to high accuracy where as it is not possible in radial

dimensions. If the radial dimensions are not controlled properly, the part will not fit into

the assembly which results into improper engaging and disengaging causing noise in the

gearbox.

As per the application stated above, to sustain function correctly which come on

synchronizer hub, we need to achieve dimensional accuracy and for this we are going to

standardise the process.

Fig. 3.1 Synchronizer hub showing different elements



4. ANALYTICAL AND THEORETICAL WORK:-

For process standardisation of synchronizer hub we have selected four major parameter of

synchronizer hub in which variation in dimensions occurs maximum are:-

1) DOP (Distance Over Pin)

2) DBP (Distance Between Pin)

3) Major OD External

4) Major ID Internal

Fig. 4.1 2D drawing of Hub

1) DOP (Distance Over Pin):-

There are two types of DOP fixtures:

a) Two pin fixture.

b) Three pin fixture.

These are selected as per the synchronizer hubs.



Fig. 4.2 Three pin fixture for DOP

Steps for measuring DOP:

1) Select the suitable fixture.

2) Check master value as per given in the process sheet. While checking confirm whether

the master value is correct or not is checked.

3) The pin diameter is decided and fixed pin in fixture.

4) A pressure of 2 bar is maintained throughout the measurement.

5) For our convenience we have decided the orientation to be clockwise and for the first

measurement the dimple should be away from the operator.

6) For the gauge setting it is tapped every time while measurement.

7) The sleeve and bolt also be checked for maintaining proper height.

8) If all setting is correct then take measurement at the three point ie. Top, mid, and

bottom of the hub.



2) DBP (Distance Between Pin) :

Fig. 4.3 Mechanical comparator for measuring DBP

Steps for measuring DBP:




3) A pressure of 2 bar is maintained throughout the measurement. While setting pressure

move dial up and down and then set 2 bar pressure on master .

4) For setting dimensions select last two digits of master value then set the value on dial

gauge.

5) For our convenience we selected two sections for measurement,

Oil groove which is exact at dimple.

Perpendicular to the oil groove

6) Then at each sections again take measurement at three point ie. Top, Mid and Bottom

of the hub.



3) Major ID ( Major Internal Diameter) :

Fig. 4.4 Mechanical comparator for measuring major ID

Steps for measuring Major ID:



2) The pin diameter is decided and fixed pin in fixture. For the Major Id flat pin is

selected.

3) A pressure of 2 bar is maintained throughout the measurement. While setting pressure

move dial up and down and then set 2 bar pressure on master.

4) For setting dimensions select last two digits of master value then set the value on dial

gauge.

5) For our convenience we selected two sections for measurement,

Oil groove which is exact at dimple.

Perpendicular to the oil groove.

6) Then at each sections again take measurement at three point ie. Top, Mid and Bottom of

the hub.



4) Major OD (Major Outer Diameter) :

There are two types of Major OD fixtures:

c) Two pin fixture.

d) Three pin fixture.

These are selected as per the synchronizer hubs.

Fig. 4.5 Three pin fixture for Major OD

Steps for measuring Major OD:

1) Select the suitable fixture.




4) A pressure of 2 bar is maintained throughout the measurement.

5) For our convenience we have decided the orientation to be clockwise and for the first

measurement the dimple should be away from the operator.

6) For the gauge setting it is tapped every time while measurement.

7) The sleeve and bolt also be checked for maintaining proper height.



8) For measurement of the Major OD the ball rest on outer surface of the teeth of hub at

exact middle of the teeth.

9) If all setting is correct then take measurement at the three point ie. Top, mid, and

bottom of the hub.



Dimensions taken by conventional method:

Forming Dimensions:

Table No. 1. Forming Dimensions

Initially we have measured the dimensions after forming for this, first the master value was

set for a pressure of 2 bar.

Then it was checked for three positions i.e. top, mid and bottom.

The sectional density of green part is also checked only after forming.

ParameterForming

specificationRow average

Min. Max. 1 2 3 4 5

Area [mm2] 2939.34 2939.34 2939.34 2939.34 2939.34

Compaction force

[kN]1686.4 1676.6 1689.1 1684.8 1686.3

Compaction

pressure [MPa]574 570 575 573 574

Weight [gm] 256.400 261.600 259.65 259.27 259.81 259.52 259.78

Top 71.512 71.510 71.513 71.512 71.513 71.512

Middle 71.504 71.501 71.502 71.502 71.503 71.502

Bottom 71.461 71.459 71.459 71.459 71.460 71.460

Top 66.553 66.556 66.554 66.552 66.553 66.554

Bottom 66.498 66.499 66.502 66.499 66.503 66.500

Top 32.981 32.983 32.982 32.982 32.989 32.983

Bottom 32.973 32.973 32.977 32.977 32.973 32.975

Top 30.882 30.875 30.880 30.881 30.883 30.880

Bottom 30.878 30.877 30.878 30.880 30.878 30.878

Top - Max 74.452 74.450 74.453 74.454 74.448 74.451

Top-Min 74.448 74.446 74.449 74.446 74.448 74.447

Middle - Max 74.439 74.439 74.440 74.438 74.433 74.438

Middle - Min 74.435 74.436 74.438 74.428 74.428 74.433

Bottom - Max 74.422 74.423 74.424 74.424 74.422 74.423

Bottom - Min 74.415 74.422 74.420 74.419 74.418 74.419

Top - Max 28.657 28.655 28.652 28.651 28.653 28.654

Top-Min 28.652 28.652 28.650 28.650 28.649 28.651

Middle - Max 28.660 28.655 28.657 28.656 28.656 28.657

Middle - Min 28.657 28.654 28.655 28.656 28.656 28.656

Bottom - Max 28.657 28.657 28.654 28.654 28.654 28.655

Bottom - Min 28.653 28.654 28.653 28.653 28.653 28.653

5.646 5.644 5.642 5.645 5.647 5.645

5.631 5.629 5.623 5.627 5.630 5.628

5.613 5.602 5.609 5.614 5.615 5.611

5.631 5.630 5.632 5.632 5.630 5.631

5.632 5.630 5.635 5.636 5.635 5.634

5.635 5.626 5.631 5.632 5.632 5.631

Forming Specification Forming Dimension

Major Dia OD 71.470 71.520

Minor Dia ID 30.860 30.900

Minor Dia OD 66.520 66.570

Major Dia ID 32.970 33.000

Top

Bottom

Slot Width 5.600 5.635

DOP 74.390 74.440

DBP 28.650 28.690



Sintering Dimensions:

Table No. 2. Sintering Dimensions

For sintering in conventional method only the belt speed and temperature are noted.

The part moves throughout the furnace for three hours and the dimensions checking

process is repeated with reference to master value.

The hardness of the part is also checked at various points on the web and boss as per the

specification on customer drawing.

ParameterSintering


Min Max 1 2 3 4 5

Top 71.547 71.553 71.552 71.555 71.548 71.551

Middle 71.560 71.559 71.564 71.558 71.557 71.560

Bottom 71.530 71.528 71.535 71.538 71.528 71.532

Top 66.587 66.594 66.589 66.595 66.586 66.590

Bottom 66.566 66.561 66.570 66.571 66.564 66.566

Top 33.013 33.009 33.012 33.010 33.007 33.010

Bottom 33.006 33.001 33.008 33.003 33.006 33.005

Top 30.912 30.919 30.913 30.910 30.908 30.912

Bottom 30.906 30.900 30.907 30.896 30.905 30.903

Top-Max 74.540 74.521 74.545 74.532 74.540 74.536

Top - Min 74.504 74.507 74.498 74.520 74.505 74.507

Middle - Max 74.510 74.481 74.498 74.498 74.510 74.499

Middle - Min 74.485 74.483 74.480 74.480 74.485 74.483

Bottom - Max 74.504 74.468 74.463 74.480 74.473 74.478

Bottom - Min 74.460 74.457 74.453 74.452 74.462 74.457

Top-Max 28.690 28.700 28.685 28.697 28.683 28.691

Top - Min 28.676 28.671 28.675 28.670 28.668 28.672

Middle - Max 28.693 28.702 28.690 28.698 28.688 28.694

Middle - Min 28.680 28.681 28.680 28.680 28.676 28.679

Bottom - Max 28.690 28.677 28.680 28.680 28.680 28.681

Bottom - Min 28.668 28.672 28.670 28.675 28.667 28.670

5.626 5.643 5.632 5.626 5.635 5.632

5.610 5.606 5.620 5.606 5.612 5.611

5.618 5.611 5.613 5.611 5.611 5.613

5.646 5.631 5.638 5.623 5.643 5.636

5.633 5.631 5.628 5.624 5.635 5.630

5.638 5.642 5.629 5.645 5.637 5.638

5.590

Sintering Specification Sintering Dimension

Top

Bottom

5.640Slot Width

DBP

DOP

33.020

30.870

Major Dia ID

Minor Dia OD

Major Dia OD

28.660 28.700

74.420 74.470

30.920Minor Dia ID

66.550 66.600

32.980

71.55071.500



Sizing Dimensions:

Table No. 3. Sizing Dimensions

In sizing the parts which are oversized are sized properly in the die, the dimensions chart

for the same is shown in above.

ParameterSizing


1 2 3 4 5

Top 71.501 71.507 71.503 71.503 71.494 71.502

Middle 71.537 71.552 71.561 71.545 71.539 71.547

Bottom 71.492 71.490 71.497 71.491 71.488 71.492

Top 66.536 66.555 66.534 66.547 66.527 66.540

Bottom 66.536 66.529 66.533 66.530 66.529 66.531

Top 33.015 33.023 33.016 33.020 33.011 33.017

Bottom 33.013 33.005 33.008 33.006 33.011 33.009

Top 30.918 30.918 30.918 30.916 30.913 30.917

Bottom 30.909 30.911 30.909 30.901 30.897 30.905

Top-Max 74.430 74.427 74.438 74.425 74.429 74.430

Top - Min 74.408 74.415 74.415 74.415 74.413 74.413

Middle - Max 74.432 74.430 74.432 74.425 74.421 74.428

Middle - Min 74.419 74.419 74.421 74.422 74.419 74.420

Bottom - Max 74.429 74.440 74.442 74.438 74.431 74.436

Bottom - Min 74.413 74.421 74.431 74.426 74.422 74.423

Top-Max 28.698 28.705 28.698 28.705 28.695 28.700

Top - Min 28.690 28.683 28.685 28.682 28.680 28.684

Middle - Max 28.700 28.702 28.695 28.706 28.694 28.699

Middle - Min 28.700 28.685 28.690 28.685 28.685 28.689

Bottom - Max 28.696 28.690 28.690 28.690 28.689 28.691

Bottom - Min 28.680 28.677 28.678 28.678 28.675 28.678

5.610 5.628 5.621 5.617 5.617 5.619

5.619 5.621 5.609 5.615 5.618 5.616

5.612 5.604 5.622 5.611 5.617 5.613

5.594 5.610 5.622 5.612 5.614 5.610

5.634 5.636 5.624 5.647 5.642 5.637

5.624 5.618 5.615 5.620 5.625 5.620

Top

Bottom

5.570

71.470

DOP 74.440

Major Dia ID 33.020

DBP 28.703

Slot Width 5.650

30.830 30.920

74.365

28.646

32.960

Minor Dia ID

Major Dia OD 71.550

Sizing Specification Sizing Dimension

Minor Dia OD 66.60066.520



Heat Treatment Dimensions:

Table No. 4. Heat Treatment Dimensions

To enhance the mechanical property like hardness, mechanical strength next step is

hardening.

The dimensions after hardening are taken which are displayed above.

Checklist:

The conventional method of measurement were leading to variations in dimensions

which in turn was leading to more scraping of parts.

Hence we prepared a standard checklist to reduce the scraping of parts and increase the

production rate.

This check list is shown below (fig. no.)

ParameterHeat Treatment


Top 71.542 71.530 71.538 71.539 71.537 71.537

Middle 71.545 71.557 71.546 71.558 71.542 71.550

Bottom 71.504 71.526 71.524 71.500 71.510 71.513

Top 66.588 66.573 66.582 66.582 66.577 66.580

Bottom 66.540 66.557 66.563 66.539 66.549 66.550

Top 32.993 32.993 32.996 32.998 32.988 32.994

Bottom 32.965 32.964 32.988 32.958 32.982 32.971

Top 30.898 30.892 30.895 30.893 30.892 30.894

Bottom 30.882 30.880 30.881 30.881 30.878 30.880

Top-Max 74.438 74.439 74.449 74.432 74.439 74.439

Top - Min 74.420 74.428 74.428 74.429 74.423 74.426

Middle - Max 74.418 74.424 74.428 74.424 74.424 74.424

Middle - Min 74.417 74.420 74.412 74.420 74.413 74.416

Bottom - Max 74.436 74.455 74.452 74.439 74.445 74.445

Bottom - Min 74.428 74.433 74.442 74.429 74.438 74.434

Top-Max 28.675 28.681 28.673 28.685 28.668 28.676

Top - Min 28.650 28.660 28.657 28.660 28.655 28.656

Middle - Max 28.684 28.690 28.678 28.675 28.677 28.681

Middle - Min 28.674 28.669 28.655 28.668 28.656 28.664

Bottom - Max 28.665 28.667 28.665 28.660 28.660 28.663

Bottom - Min 28.647 28.655 28.647 28.648 28.645 28.648

5.638 5.669 5.617 5.653 5.640 5.643

5.650 5.657 5.656 5.651 5.649 5.653

5.649 5.663 5.617 5.656 5.638 5.645

5.655 5.633 5.647 5.634 5.651 5.644

5.678 5.636 5.653 5.661 5.663 5.658

5.676 5.671 5.676 5.686 5.683 5.678

66.500

32.930Major Dia ID 33.029

DOP

Heat Treatment

SpecificationHeat Treatment Dimension

Minor Dia OD 66.600

Major Dia OD 71.55071.450

DBP 28.703

74.345

28.636

30.940

Top

Slot Width 5.650

Minor Dia ID

Bottom

5.550

30.800

74.445



Table No.5 Checklist

Through this checklist we analysed every parameter from powder mixing to hardening.



(Note: The powder is supplied by Hogonus Ltd. Therefore no changes are made in its

compositions in the company.)

Forming Dimensions:

In conventional method, we take the dimensions after each process but according to

checklist.

In forming we have also noted the compaction force, weight and compaction pressure for

each part under observance.

The tool dimensions for the same part are also noted.

The dimensions for the part are entered in the table and their average value is calculated.

The sprinback is calculated by the following formula,

Sprinback = (Avg. dimensions – tool dimensions) / tool dimensions



Para

meter

Form

ing

Row

aver

age

Over

all av

erag

e

Min.

Max

.1

24

5

Area

[mm2

]29

39.34

2939

.3429

39.34

2939

.34

Comp

actio

n for

ce

[kN]

1752

.317

55.1

1755

.517

60.8

Comp

actio

n

pres

sure

[MPa

]59

659

759

759

9

Weig

ht [g

m]25

6.400

261.6

0025

8.528

258.5

7525

8.706

258.7

28

Top

71.51

271

.510

71.51

271

.513

71.51

271

.269

0.34

Midd

le71

.504

71.50

171

.502

71.50

371

.502

71.26

90.3

3

Botto

m 71

.461

71.45

971

.459

71.46

071

.460

71.26

90.2

7

Top -

Max

33.00

032

.992

32.99

932

.994

32.99

6

Top-

Min

32.95

032

.955

32.94

832

.950

32.94

9

Midd

le - M

ax32

.985

32.97

632

.984

32.97

532

.980

Midd

le - M

in32

.954

32.95

432

.947

32.94

932

.949

Botto

m - M

ax32

.974

32.96

532

.970

32.96

332

.968

Botto

m - M

in32

.953

32.95

432

.946

32.94

932

.948

Top -

Max

74.41

074

.405

74.40

774

.406

74.40

7

Top-

Min

74.39

274

.389

74.38

574

.393

74.39

0

Midd

le - M

ax74

.400

74.40

474

.400

74.40

374

.402

Midd

le - M

in74

.400

74.39

974

.392

74.39

874

.398

Botto

m - M

ax74

.379

74.38

074

.376

74.38

074

.378

Botto

m - M

in74

.370

74.36

574

.370

74.36

574

.369

Top -

Max

28.70

028

.699

28.70

028

.700

28.69

9

Top-

Min

28.64

328

.651

28.64

828

.650

28.64

9

Midd

le - M

ax28

.690

28.68

928

.689

28.69

028

.689

Midd

le - M

in28

.640

28.64

628

.640

28.64

428

.643

Botto

m - M

ax28

.672

28.67

128

.674

28.67

228

.672

Botto

m - M

in28

.634

28.63

728

.635

28.63

928

.637

32.96

0

74.18

6

28.66

4

0.04%

0.01%

-0.01

%

0.29%

0.047

0.031

0.020

0.017

0.004

0.010

0.01%

28.66

6

-0.03

%28

.654

0.046

0.035

0.03%

28.67

4

28.70

028

.634

28.66

5

0.050

74.36

574

.391

74.40

0

74.37

4

DBP

28.65

028

.690

DOP

74.37

074

.430

74.39

9

74.41

00.2

9%

0.25%

Majo

r Dia

ID33

.000

33.00

032

.940

32.96

532

.970

32.97

3

32.96

4

32.95

8

71.49

1M

ajor D

ia OD

71.43

071

.500

71.51

371

.459

Form

ing S

pecif

icatio

nFo

rming

Dim

ensio

nDO

P DB

P

Avg f

or

Max

.M

in.Ov

ality

Tool

dimSp

ringb

ack

Tab

le N

o.6

Form

ing D

imen

sion

s



Sintering Dimensions:

Para

meter

Sinter

ing

Spec

ificati

on

12

45

Row

Avg.

Form

Dim

.DC

Ovali

ty

DOP

DBP

Avg f

or

grap

hs

Max

.M

in.Av

erag

e

Top

71.54

771

.553

71.55

571

.548

71.55

171

.512

0.05%

Midd

le71

.560

71.55

971

.558

71.55

771

.560

71.50

20.0

8%

Botto

m 71

.530

71.52

871

.538

71.52

871

.532

71.46

00.1

0%

Top-

Max

33.01

233

.008

33.00

433

.010

33.00

932

.996

Top -

Min

32.96

632

.970

32.97

332

.970

32.97

032

.949

Midd

le - M

ax33

.005

33.00

433

.004

33.00

333

.004

32.98

0

Midd

le - M

in32

.970

32.97

232

.971

32.97

332

.972

32.94

9

Botto

m - M

ax33

.003

33.00

533

.009

33.00

233

.004

32.96

8

Botto

m - M

in32

.976

32.97

932

.975

32.97

932

.978

32.94

8

Top-

Max

74.40

974

.417

74.41

874

.419

74.41

674

.407

Top -

Min

74.40

274

.391

74.40

074

.410

74.40

374

.390

Midd

le - M

ax74

.411

74.41

274

.428

74.42

774

.421

74.40

2

Midd

le - M

in74

.407

74.40

874

.411

74.42

374

.414

74.39

8

Botto

m - M

ax74

.404

74.40

574

.422

74.42

274

.415

74.37

8

Botto

m - M

in74

.397

74.39

374

.404

74.40

974

.402

74.36

9

Top-

Max

28.70

528

.700

28.69

628

.704

28.70

228

.699

Top -

Min

28.66

028

.664

28.66

528

.665

28.66

428

.649

Midd

le - M

ax28

.710

28.70

728

.708

28.71

028

.709

28.68

9

Midd

le - M

in28

.665

28.66

628

.669

28.67

128

.668

28.64

3

Botto

m - M

ax28

.696

28.69

928

.702

28.69

728

.698

28.67

2

Botto

m - M

in28

.664

28.66

428

.664

28.66

728

.665

28.63

7

0.05%

0.03%

0.08%

0.10%

0.05%

0.07%

0.10%

0.01%

0.02%

0.041

0.033

0.032

0.027

0.014

0.007

0.013

0.038

28.68

428

.689

28.68

2

74.41

8

74.40

9

DBP

28.66

028

.700

28.68

3

28.71

028

.660

DOP

74.39

074

.440

74.41

0

74.42

874

.391

74.41

2

32.98

9M

ajor D

ia ID

32.98

033

.020

33.01

232

.966

32.98

9

32.98

8

32.99

1

0.039

71.52

871

.547

Sinter

ing

Majo

r Dia

OD71

.480

71.53

071

.564

Tab

le N

o.

7 S

inte

rin

g D

imen

sion

s



In sintering we checked the belt speed with the help of scale and stopwatch for 1 m. length

(standard belt speed should be 128 mm/min).

We have noted the temperatures of all zones and also the compositions of gases like

Nitrogen, Ammonia and LPG in m3/hrs to avoid the oxidation of the part.

The dew point temperature and blower rpm are also noted.

The furnace constitutes of four zones,

Preheating zone (temp. 10000C)

Actual sintering zone

Sintering hardness zone (840 – 11400C)

Fast cooling zone

The hub is mounted on ceramic bobbin since ceramic can sustain in system high

temperature and the part gets equally heated from all sides.

After sintering the hardness of the part is checked.



Sizing Dimensions:

For sizing process, we note the tool dimensions and part are sized in the die.

The spring back of part are calculated after sizing.

Machining is done only if required and it is done only on Boss and web.

Param

eter

12

45

Row A

vg.To

ol Dim

Spring

back

Ovalit

y

DOP D

BP

Avg f

or

graphs

Max.

Min.

Avera

ge

Top

71.501

71.507

71.503

71.494

71.501

-0.03%

Middl

e71.

51271.

55271.

50971.

50371.

5190.0

0%

Bottom

71.

49271.

49071.

49171.

48871.

490-0.

04%

Top-M

ax33.

00933.

00133.

00033.

00633.

004

Top -

Min

32.961

32.962

32.966

32.962

32.963

Middl

e - M

ax32.

99732.

99632.

99732.

99732.

997

Middl

e - M

in32.

96332.

96332.

96232.

96532.

963

Bottom

- Max

32.993

32.994

33.000

32.994

32.995

Bottom

- Min

32.968

32.967

32.964

32.970

32.967

Top-M

ax74.

38474.

38474.

38374.

38274.

383

Top -

Min

74.374

74.374

74.377

74.378

74.376

Middl

e - M

ax74.

41074.

40974.

41274.

40974.

410

Middl

e - M

in74.

40174.

40374.

40574.

40474.

403

Bottom

- Max

74.373

74.374

74.383

74.378

74.377

Bottom

- Min

74.366

74.368

74.355

74.368

74.364

Top-M

ax28.

70828.

70028.

69828.

70428.

703

Top -

Min

28.663

28.663

28.665

28.662

28.663

Middl

e - M

ax28.

71428.

71028.

70828.

71128.

711

Middl

e - M

in28.

67028.

67028.

67028.

66928.

670

Bottom

- Max

28.696

28.695

28.699

28.695

28.696

Bottom

- Min

28.660

28.660

28.659

28.661

28.660

71.521

74.350

28.668

0.04%

0.08%

0.03%

0.041

0.036

0.033

0.028

0.008

28.714

28.659

28.684

28.690

28.678

74.407

74.371

DBP

28.646

28.703

28.683

0.007

0.013

0.039

DOP

74.335

74.410

74.380

74.412

74.355

74.386

32.982

Major

Dia ID

32.960

33.020

33.009

32.961

32.983

32.980

32.981

0.041

Sizing

Speci

fication

Sizing

Major

Dia OD

71.460

71.520

71.552

71.488

71.504

0.001

0.001

0.000

33.021

-0.001

-0.001

-0.001

Tab

le N

o.8

Siz

ing D

imen

sion

s



Heat Treatment Measurement:

12

45

Row

Avg.

Siz. D

im.

DCOv

ality

DOP

DBP

Avg f

or

graph

s

Max

.M

in.Av

erage

Top

71.54

271

.530

71.53

971

.537

71.53

771

.502

0.035

Midd

le71

.545

71.55

771

.558

71.54

271

.551

33.00

438

.547

Botto

m 71

.504

71.52

671

.500

71.51

071

.510

32.96

338

.547

Top-M

ax32

.998

32.99

132

.989

32.99

132

.992

33.00

4

Top -

Min

32.93

932

.939

32.93

932

.940

32.93

932

.963

Midd

le - M

ax32

.984

32.98

532

.985

32.98

232

.984

32.99

7M

iddle

- Min

32.94

132

.941

32.94

032

.942

32.94

132

.963

Botto

m - M

ax32

.978

32.98

332

.993

32.98

032

.984

32.99

5

Botto

m - M

in32

.953

32.95

132

.952

32.95

532

.953

32.96

7

Top-M

ax74

.392

74.40

074

.395

74.39

574

.396

74.38

3

Top -

Min

74.38

574

.383

74.37

574

.390

74.38

374

.376

Midd

le - M

ax74

.395

74.39

874

.405

74.39

874

.399

74.41

0M

iddle

- Min

74.39

174

.390

74.39

074

.395

74.39

274

.403

Botto

m - M

ax74

.400

74.40

274

.405

74.40

674

.403

74.37

7

Botto

m - M

in74

.385

74.38

974

.405

74.39

174

.393

74.36

4

Top-M

ax28

.678

28.66

828

.668

28.67

228

.672

28.70

0

Top -

Min

28.62

628

.626

28.62

528

.625

28.62

628

.604

Midd

le - M

ax28

.668

28.66

628

.671

28.66

428

.667

28.69

9M

iddle

- Min

28.62

828

.629

28.62

928

.628

28.62

928

.689

Botto

m - M

ax28

.660

28.66

428

.628

28.66

128

.653

28.69

1

Botto

m - M

in28

.630

28.63

028

.631

28.63

128

.631

28.59

8

-0.03

4

-0.04

2

-0.03

6

-0.01

8

-0.01

8

-0.01

3

0.010

-0.01

1

0.027

0.039

0.023

0.053

0.043

0.031

0.012

28.67

828

.625

28.64

628

.648

28.64

2

74.39

5

74.39

8

DBP

28.63

628

.703

28.64

9

0.008

0.011

0.046

DOP

74.34

574

.445

74.38

9

74.40

674

.375

74.39

4

Majo

r Dia

ID33

.029

32.99

832

.939

32.96

532

.930

32.96

6

32.96

3

32.96

8

71.53

3M

ajor D

ia OD

71.55

871

.500

Param

eter

Heat

Trea

tmen

t

Spec

ificati

on

Heat

Trea

tmen

t

Tab

le N

o. 9

Hea

t T

reatm

ent

Dim

ensi

on

s



We are noted the temperatures of all zones and also the compositions of gases like

Nitrogen, Ammonia and LPG in m3/hrs to avoid of the part the oxidations of the part.

The dew point temperature and blower rpm are also note.

The hub is mounted on ceramic bobbin since ceramic can sustain in system high

temperature and the part gets equally heated from all sides.

After sintering the hardness of the part is checked.

Pallets making:

Pallets are pressed using UTM (Universal Testing Machine) to check the actual

springback and compressibility of the component.

Pallets are prepared from the same mix as that of the part and are sintered at same

temperature.

The pallets dimensions checked are Diameter, height and Weight.

The standard pressure of 400 MPa, 500MPa, 600 MPa and 650 MPa are set on the

UTM.

The density of pallets are calculated as follows,

Density ( ϱ) = Mass/ Volume

Volume = (π/4)* d2*h

The graph of density Vs pressure and spring back Vs Green density is plotted as shown in

the fig.



Table No.10.Pallet Dimensions

Fig. 4.6 Density Vs Compaction Pressure



Fig. 4.7 Springback Vs Green Density



5. RESULT AND DISCUSSIONS:

Fig.5.1 DOP Variation (Before)

Fig.5.2 DOP Variation (After)

74.320

74.340

74.360

74.380

74.400

74.420

74.440

74.460

74.480

74.500

74.520

74.540

Forming Sintering Sizing Heat Treatment

DOP taper

UL

LL

Tool

ActualDim

ensi

on

s in

mm

74.320

74.340

74.360

74.380

74.400

74.420

74.440

74.460


DOP taper

UL

LL

Tool

Actual

Dim

ensi

on

s in

mm

Processes

Processes



Fig.5.3 DBP Variation (Before)

Fig.5.4 DBP Variation (After)

28.600

28.620

28.640

28.660

28.680

28.700

28.720

28.740


DBP taper

UL

LL

Tool

Actual

28.600

28.620

28.640

28.660

28.680

28.700

28.720

28.740


DBP taper

UL

LL

Tool

Actual

Processes

Dim

ensi

on

s in

mm

Processes

Dim

ensi

on

s in

mm



Fig.5.5 Major ID Variation (Before)

Fig.5.6 Major ID Variation (After)

32.860

32.880

32.900

32.920

32.940

32.960

32.980

33.000

33.020

33.040

33.060

33.080


Major ID taper

UL

LL

Actual

32.860

32.880

32.900

32.920

32.940

32.960

32.980

33.000

33.020

33.040

33.060

33.080


Major ID taper

UL

LL

Actual

Processes

Dim

ensi

on

s in

mm

Processes

Dim

ensi

on

s in

mm



6. CONCLUSIONS:-

1) Major variation in dimensions are seen in four parameters DOP, DBP, Major ID and Major

OD and we have selected them for our project purpose. Every minor change at every step is

noted and it is seen that on an average the top portion of the hub has major deviation i.e. the

hub appears to be slight taper.

2) The apparent density is the ratio of volume to weight of loosely filled mixture and it is

between 2.95 to 3.2 gm/cc. The flow of powder is for 30 sec max.

3) P/M technology has density dependent properties. Hence, compaction force has significant

effect on the properties of the component. The density specification for various synchronizer

hubs may vary from a minimum of 6.8gm/cc to a maximum of 7.1gm/cc. The variation of

density Vs compaction force is shown in fig no.4.6

4) The springback of the hub depends on compaction pressure. As the compaction pressure

increases, springback increases. The springpack of pellets and the parts is different. It is

more for the pellets than that of the part.

5) The change in dimensions in pellet and part are noted as shown in table no.10. The

dimensional change in such a record is useful in tool selection and also in regular production.

6) We have used two sided compaction method. Hence continuous usage of punch wears it

which leads to variation in fill height. The variation in fill height affects the sectional density

measured after forming. With increasing distance from the face of the compacting punch, the

axial stress which is available for the local densification of the powder decreases. , maximum

variation in the geometry of synchronizer hub is observed after sintering.

7) Compaction force and springback are interdependent. The calculation of springback gives us

values which we can use to study the condition of tool. If it is observed that the springback

values are more than expected, it is an indication to us to change the tool or redesign the tool.

Thus the springback is an important factor for tool design. The compressibility curve



(shown in fig no.4.6) helps us to understand how green density changes with the change in

compaction pressure. For example if we select 500 MPa pressure for a particular component

we get density as 6.9 gm/cc , but in regular practice if this value changes to +-500 , the small

change in green density is not possible to note. But this leads to change in tool dimensions

and its affects the part geometry.

8) We have kept a constant belt speed of 128mm/min (depend on length of sintering zone) since

variation in belt speed leads to the component being subjected to less or more amount of heat

which in turn affects the geometry of the component.

9) During sizing, only the radial dimensions are controlled i.e. taper reduction and profile

improvement is done. If there is taper, it becomes difficult for the hub to fit into the

assembly.



7. REFERENCES:-

[1] A.K.Sinha “Powder Metallurgy”.

[2] Shidney Avner “Introduction to Physical Metallurgy”.

[3] V.D.Kodgire “Material Science and Metallurgy for Engineers”.

[4] Myeong-Sik Jeong a, Jun-HwanYoo b, Sung-HanRhim c, Sang-KonLee a, Soo-IkOhb,n “A

unified model for compaction and sintering behaviour of powder processing”.

[5] www.sciencedirect.com

[6] H.Hofmann, P.Bowen “Powder Technology”.

[7] Ottmar Back, Head of Product Management “Basics of Synchronizers”.

[8] ANA PASTOR BEDMAR “Synchronization processes and synchronizer mechanisms

in manual transmissions” Modelling and simulation of synchronization processes

Department of Applied Mechanics Division of Dynamics CHALMERS

UNIVERSITY OF TECHNOLOGY Goteborg, Sweden 2013.

[9] Manufacturing Science and Technology.

http://www.sciencedirect.com/

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