Powder metallurgy is a process that involves producing metal powders and using them to make finished parts. It consists of three main stages: 1) physically powdering the primary material, 2) injecting the powder into a mold or passing it through a die to form a weakly cohesive pre-form, and 3) applying high pressure, temperature, and time to fully form the final part. The process allows for high production rates, low material waste, and flexibility in alloy choices. Parts are made through blending metal powders, compacting them into shapes using dies and presses, and sintering the compacts to strengthen the bonds between particles.

1. POWDER
METALLURGY
Powder Metallurgy

2.  Essentially, Powder Metallurgy (PM) is an art & science of
producing metal or metallic powders, and using them to make
finished or semi-finished products.
Powder Metallurgy

3.  Powder metallurgy is a forming and fabrication technique
consisting of three major processing stages;
1. The primary material is physically powdered , divided into many
small individual particles.
2. The powder is injected into mould or passed through die to
produce weakly cohesive structure . It is very near to the
dimensions of the object to be manufactured.
3. Finally the end part is formed by applying pressure , high
temperature , long setting time.
Powder Metallurgy

4. 1. The production can be fully automated, therefore,
2. Mass production is possible
3. Production rate is high
4. Over-head costs are low
5. Break even point is not too large
6. Material loss is small
7. Virtually unlimited choice of alloys, composites, and
associated properties
8. Long term reliability through close control of
dimensions and physical properties
9. no machining is required , hence Very good material
utilization ,
Powder Metallurgy

5.  High tooling and equipment costs.
 Metallic powders are expensive.
 Problems in storing and handling metal powders.
Degradation over time, fire hazards with certain metals such as
Al, Mg, TI etc.
 Limitations on part geometry because metal powders do not
readily flow laterally in the die during pressing.
 Variations in density throughout part may be a problem,
especially for complex geometries.
Powder Metallurgy

6. 1. Due to Porosity poor corrosion resistance, ductility , toughness
etc.
2. Large components cannot be produced on a large scale.
3. Some shapes are difficult to be produced by the conventional
p/m route.
Powder Metallurgy

7.  Powder production
 Blending or mixing
 Powder compaction
 Sintering
 Finishing Operations
Powder Metallurgy

8. Powder Metallurgy

9. Conventional powder
metallurgy production
sequence:
blending
compacting
Sintering
Powder Metallurgy

10.  Blending a coarser fraction with a finer fraction ensures that the
interstices between large particles will be filled out.
 Powders of different metals and other materials may be mixed in
order to impart special physical and mechanical properties
through metallic alloying.
 Lubricants usually added to reduce friction between die and wall
and punches .
 Binders such as wax or thermoplastic polymers are added to
improve green strength.
Powder Metallurgy

11. Powder Metallurgy
A mixer suitable for blending metal
powders.
Some common equipment geometries used for
blending powders
(a) Cylindrical, (b) rotating cube, (c) double
cone, (d) twin shell

12. Powder Metallurgy
Blending - Micro Metals.mp4

13. Application of high pressure to the powders to form them
into the required shape.
Conventional compaction method is pressing, in which
opposing punches squeeze the powders contained in a die.
 The work part after pressing is called a green compact,
the word green meaning not yet fully processed.
 The green strength of the part when pressed is adequate
for handling but far less than after sintering.
Powder Metallurgy

14.  Press powder into the desired shape and size in dies using a
hydraulic or mechanical press
 Pressed powder is known as “green compact”
 Stages of metal powder compaction:
Powder Metallurgy
Compacting

15. Heat treatment to bond the metallic particles, thereby increasing
strength and hardness.
Usually carried out at between 70% and 90% of the metal's melting
point
Powder Metallurgy

16.  Parts are heated to ~80% of melting temperature.
 Transforms compacted mechanical bonds to much stronger metal
bonds.
 Many parts are done at this stage. Some will require additional
processing.
Powder Metallurgy
Sintering

17. Figure: Sintering on a microscopic scale: (1) particle bonding is
initiated at contact points; (2) contact points grow into "necks"; (3) the
pores between particles are reduced in size; and (4) grain boundaries
develop between particles in place of the necked regions.
Powder Metallurgy
Sintering Sequence
 Transforms compacted mechanical bonds to much stronger
metallic bonds.

18. PM Parts
Powder Metallurgy

19. Connecting Rods:Powdered Metal Transmission Gear

Powder Metallurgy

20. Powder Metallurgy
The Powder Metallurgy Process (Flow of Value).mp4

21. Powder Metallurgy