Powder metallurgy is a process that involves producing metal powder and compacting and sintering it to form objects. It has three main steps - powder production, compacting, and sintering. Powder metallurgy allows for near-net shape production with few secondary operations and can be used to make complex parts from various alloys. Some examples where it is used include auto transmission sprockets and main bearing caps for automobile engines. The process offers advantages like net-shape production, ability to use high-melting metals, and high production rates. However, it also has disadvantages such as high powder production costs and limited part geometries.

1. Powder Metallurgy

2. Powder Metallurgy
• Introduction
• The Use Of metal powder in industrial application
• P/M Manufacturing Techniques
• Application general Case studies
• Advantages
• Disadvantages

3. Introduction…..
• Definition:
“ Powder metallurgy is an art and science of producing fine metal
powder and then making objects from individual , mixed or alloyed
metal powder with or without the inclusion of non metallic
constituents”

4. Continue…
• For making a component by P/M
(i) The metal in The Powder Form must be able to respond to solid
phase welding
(ii) The metal powder must be capable of sufficiently close packing
under pressure to permit welding to take place and in case of alloying
, be capable of being sufficiently intimately mixed

6. Powder metallurgy consist three main steps
• A) Powder Production
• B) Compacting
• C) Sintering

7. (A)Powder Production
•Atomization
• Reduction
• Electrolysis
• Crushing
• Etc…

8. (A) Powder production By Atomization
• Gas Atomization
---Spherical powder Particals
---Good “flow ability”
• Water Atomization
---Irregular powder Particals
---Good Compatibility

12. (B) Compacting of Metal Powder
• Compaction is the step where the blended powders are pressed
into various shapes in dies

13. Continue….
• Purposes of compaction are to obtain the required shape,
density and particle-to-particle contact
• Pressed powder is known as green compact
• Density depends on the pressure applied
• Higher the density of the compacted part, the higher are its
strength and elastic modulus

14. Continue…….
• May be necessary to use multiple punches to ensure that the
density is more uniform throughout the part

15. Continue
• Compacting pressure required depends on the characteristics
and shape of the particles, method of blending and lubricant

16. ( c ) Sintering
Heat treatment to promote metallurgical integrity
•Metallurgical bonding
• Densification (Shrinkage)
•Pore Elimination

17. Sintering
• Sintering is the process whereby green compacts are heated in
a furnace to below the melting point but high enough to allow
bonding (fusion) of the individual particles

18. Continue….
• Strength of the bond between the particles depends on the
complex mechanisms of diffusion of:
1. Plastic flow
2. Evaporation of volatile materials in the compact
3. Recrystallization
4. Grain growth
5. Pore shrinkage

19. Continue…..
• Continuous-sintering furnaces have 3 chambers:
1. Burn-off chamber
2. High-temperature chamber
3. Cooling chamber
• The sintering mechanisms are diffusion, vapor-phase
transport, and liquid-phase sintering

20. Continue….
Mechanical Properties
• Affecting mechanical properties are temperature, time, and
processing history
• Porosity cannot be avoided completely due to voids remaining
after compaction and gases evolve during sintering

22. Case Study 1
Component: Auto Transmission sprockets

23. Parameter of auto transmission sprockets
• Size: OD drive:90-100mm
OD driven:100-106mm
• Weight: Drive:450-590 g
Driven:505-570g
• Alloy :steel
• Tensile strength: 860MPa
• Elongation:1.5%
• Apparent Hardness: 60 HRC
• Density:7.8 g/cm3,surface density
7.0g/cm3,core density
• Heat Treatment: vacuum carburizing
• Annual Production:20,00,000

24. Description:-
• Steel is mainly used in manufacturing process of auto transmission
sprockets.
• Auto transmission sprockets are commonly manufacture by powder
metallurgy process.
• High-performance PM steel automatic transmission sprockets-one
drive and one driven-are compacted, sintered and selectively
densified.
• The teeth are further densified by cold working process and then
vacuum carburized, producing a precisely controlled case on critical
journal and tooth flank surface.

25. • This provides high strength ,exceptional bearing and surface
durability.
• The surface density of parts is 7.8g/cm3,and its gradually falling to
lower level towards the core.
• The core regions are not highly stress and remain at a density of 7
g/cm3.
• There are two components in a set in each transmission that transmit
power from the engine to the transmission via silent chain.

26. Case studies : 3 Main Bearing Cap for
Automobile Engines

27. Details
• Weight : 0.755 kg
• Alloy : proprietary steel
• Tensile Strength : 450 MPa
• Elongation : 3%
• Apparent Hardness : 70 HRB
• Density : 6.6 g/cm^3
• Fatigue Endurance Limit : 160 Mpa
• Secondary Operations : Machining
• Alternative Process : Nodular iron casting

28. Description :
• This main bearing cap (mbc) is used in general motors engines. The
engine contains three caps weighing about 2.2 kg.
• Main bearing caps guide and retain the engine crankshaft which must
be held securely in place but turn freely.
• The MBC is attached to the engine block with bolts through long bolt
holes which also locate the cap along the axis of the engine.
• The part is fit in the channel and it is fit in block fore stability.

29. • The joint faces must be flat to ensure solid contact with the block.
• The surface directly under the bolt head must be flat and parallel to
ensure uniform pressure at the high clamp loads used.
• There is a notch in the arch of the cap which locates the bearing
shells in place.

30. • MBCs made from gray cast iron, the competitive material, are cast in
to a sand mold to produce a “loaf”, which required broaching, drilling,
spot facing, and milling before the loaf is cut into individual MBC
• This process produces a 60% yield of main bearing caps from the cast
iron loaf
• PM provided the necessary fatigue strength,quality,machinability and
economy of near-net-shape-design.

31. Advantages Of Powder Metallurgy
• 1. Powder metallurgy produces near net shape components. The
technique required few or no secondary operations.
• 2. Parts of powder metallurgy can be produce from high melting
point refractory metals with less cost and difficulties.
• 3. The tolerance of components produced by this technique have
quite high tolerance, therefore no further machining is not required.
• 4. This technique involves high Production Rate along with low Unit
Cost.
• 5. It can produce complicated forms with a uniform microstructure.

32. Continue….
• 6. Powder metallurgy has full capacity for producing a variety of
alloying systems and particulate composites.
• 7. This technique has flexibilities for producing PM parts with
specific physical and mechanical properties like hardness, strength,
density and porosity.
• 8. Powder metallurgy can be used to produce bi-metallic products,
porous bearing and sintered carbide.
• 9. Powder metallurgy makes use of 100% raw material as no
material is wasted as scrap during process

33. Disadvantages of powder metallurgy
• 1. The production of powder for metallurgy is very high.
• 2. The products of metallurgy can have limited shapes and features.
• 3. This technique causes potential workforce health problems from
atmospheric contamination of the workplace.
• 4. The tooling and equipments require for powder metallurgy are
very expensive, therefore becomes main issue with low production
volume.

34. Continue…
• 5. It’s difficult to produce large and complex shaped parts with
powder metallurgy.
• 6. The parts produce by powder metallurgy have low ductility and
strength.
• 7. Finally divided powder like aluminum, magnesium, titanium and
zirconium are fire hazard and explosive in nature.
• 8. This technique is not useful for low melting powder such as zinc,
cadmium and tin as they show thermal difficulties during sintering
operations.

35. References
www.google.com
www.wikipedia.org
www.youtube.com
Material Science and Physical metallurgy by O.P Khanna

36. Prepared by…..
130110120019 Bhavin Kevar
130110120028 Tanuj Parikh
130110120034 Harshil Patel
1301101200 Roshan Patel
1301101200 Shubham Shanghvi
Guided by,
Prof. Tejas D Patel
Prof. Saurin M Sheth