Powder metallurgy

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!