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B Y O M E R WA T H I Q A L A N I
POWDER METALLURGY
OBJECTS
• Introduction
• Why Pm?
• Advantages of pm
• Materials for Pm
• Operations of PmPowder production
Blending and mixing of powders
Compaction
Sintering
Finishing operations
• Application
INTRODUCTION
• A fabrication technique involves the compaction of
powdered metal, followed by a heat treatment to
produce a more dense piece.
• Powder metallurgy is especially suitable for metals
having low ductility's
having high melting temperatures
WHY PM?
• The capability to produce parts to near net shapes
• Properties of components can vary in a wide range
(e.g.. porosity, electric conductivity, strength,
…etc.)
• The economics of the overall operation
• Alloys with special properties
ADVANTAGES OF PM
• PRECISE CONTROL : properties of end products can be suited to the demands of applications
• CUSTOM-MADE COMPOSITION : widely different characteristics can be compacted
• PHYSICAL PROPERTIES : properties can be altered easily by this method(e.g. density, porosity)
• NEAR NETT SHAPING BECOMES NETT SHAPING eliminating the further processes (e.g. machining)
MATERIALS FOR PM
• Metal powders (Fe, Cu, Ni, Ti, Co, W, Mo, …stb.)
• Alloys (HSS, bronze, stainless steels, …etc.)
• Non-metallic powders (graphite, metal carbides,
oxides, …etc.)
OPERATIONS OF PM
1. Powder production(metals, alloys, metalloids)
2. Blending and mixing of powders
3. Compaction
4. Sintering
5. Finishing operations
POWDER PRODUCTION
POWDER PRODUCTION
SHAPE AND SIZE OF POWDERS
• Shape and size of powders depend on the method
of production
• Particle size range: 0,001…1 mm
• Shapes (one-, two, three dimensional):
spherical
elongated
irregular
porous
BLENDING AND MIXING OF POWDERS
• For successful results in compaction and sintering,
the starting powders must be homogenized
• Blending - powders of the same chemistry but possibly different particle sizes are intermingled
• Mixing - powders of different chemistries are
combined
• PM technology allows mixing various metals into alloys that would be difficult or impossible to produce by other means
BLENDING AND MIXING OF POWDERS
Blending and mixing are accomplished by
mechanical means:
COMPACTION
• Application of high pressure to the powders to form
them into the required shape
• The 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
COMPACTION
COMPACTION
COMPACTION
• There are different ways to improve the density
distribution:
SINTERING
• Compressed metal powder is heated in a controlled-atmosphere
furnace to a temperature below its melting point( between 70% to
90% of melting point) , but high enough to allow bounding of the
particles
SINTERING
• The primary driving force for sintering is not the
fusion of material, but formation and growth of
bonds between the particles
FINISHING OPERATIONS
• Coining and sizing: improve dimensional accuracy,
strength and surface finish
• Cold forging, upsetting: modify shape, increase
strength
• Impregnating with fluid: bearings and bushes
• Infiltration: molten metal infiltrates the pores
APPLICATION
Process:
•Welding
•Hot isostatic compaction
•Rolling
•Forging
Product: Bars, forged
parts
High Speed Steels
APPLICATION
cutting tools
W- and Ti-carbide
plates for highspeed
cutting
APPLICATION
APPLICATION
Thank you!