Department of Materials Engineering at Isfahan University of Technology

Chapter 2: Importance of Powder

Metallurgy

Course Objective...To understand the importance of powder metallurgy

process and its applications

This course will help you :

To understand powder metallurgy process as a

manufacturing technique and its process parameters

Department of Materials Engineering at Isfahan University of Technology

INTRODUCTION

Department of Materials Engineering at Isfahan University of Technology

Definition

Powder metallurgy, or PM, is a process for forming parts by

heating compacted powders to just below their melting

points. Although the process has existed for more than 100

years, over the past quarter century it has become widely

recognized as a superior way of producing high-quality

parts for a variety of important applications. This success is

due to the advantages the process offers over other

forming technologies such as forging and metal casting,

advantages in material utilization, shape complexity, near-

net-shape dimensional control, among others. These, in

turn, contribute to sustainability, making PM a recognized

green technology

INTRODUCTION

Department of Materials Engineering at Isfahan University of Technology

Eliminates or minimizes machining by producing parts at, or close

to, final dimensions.

Eliminates of minimizes scrap losses by typically using more than

97% of the starting raw material in the finished part.

Permits a wide variety of alloy systems.

Produces good surface finishes.

Provides controlled porosity for self-lubrication or filtration.

Facilitates manufacture of complex or unique shapes which would

be impractical or impossible with other metalworking processes.

Offers long-term performance reliability in critical applications.

Is cost-effective.

Advantages of Powder Metallurgy

INTRODUCTION

Department of Materials Engineering at Isfahan University of Technology

INTRODUCTION

POWDER METALLURGY is the study of the processing of metal

powders, including the fabrication, characterization, and conversion of

metal powders into useful engineering components

Department of Materials Engineering at Isfahan University of Technology

Three main steps for P/M2There is an interdependence

between several aspects of

P/M2

INTRODUCTION

Department of Materials Engineering at Isfahan University of Technology

Uses of PM2 Products

Trends of growing of PM2 PM2 Structural Components Market

(2000)

PM2 components are used in a variety

of markets, most notably are the metal

cutting and automotive industries.

Other important markets are hand

tools, household appliances, industrial

motors, surgical instruments, turbine

engines…

Department of Materials Engineering at Isfahan University of Technology

Structure of the PM2 Industry

http://www.mpif.org/IntroPM/future.asp?linkid=9

Information about P/M and PM2 industry can be find in the webpage

of the Metal Powder Industry Federation

Department of Materials Engineering at Isfahan University of Technology

P/M net-shape gears are common, save machining time

Method:• Make fine metal powders and sort

• Mix powders to get “alloy”

• Iron alloys most common, also Bronze

• Compaction

• Powder is pressed into a “green compact”

• 20,000-100,000psi pressure

• Still very porous, ~70% density

• May be done cold or warm (higher density)

• Sintering

• Controlled atmosphere: no oxygen

• Heat to 0.75xTmelt

• Particles bind together

• Part shrinks in size

• Density increases, up to 95%

• Strength ~=~ Density

P/M (vs. Casting):

• Mass produce small steel parts, net-shape

• Less waste

• Unusual “alloys”

• Range of densities, porosity (adv or disadv)

• Less energy use

• But: Smaller parts and less complexity (2.5D)

Powder Metallurgy Process

Department of Materials Engineering at Isfahan University of Technology

P/M PROCESSING

POWDER

PROCESSING

PROPERTIES

Powder fabrication

Size and shape characterization

Microstructure (eg. dendrite size)

Chemical homogeneity, and ppt. size

Compaction

Sintering

Forging/Hot pressing

Density, Porosity

Ductility, Strength

Conductivity

Other functional properties

Department of Materials Engineering at Isfahan University of Technology

Slightly porous appearance is common

Range of particle sizes

Powder Metallurgy Process

Department of Materials Engineering at Isfahan University of Technology

APPLICATIONS OF P/M PARTS

Abrasives: metal polishing wheels, grinding media

Agriculture: lawn & garden equip.

Aerospace: jet engines, heat shields, rocket nozzles

Ceramics: high temperature components, thermal shields, fuel

cells

Electronic: capacitors, resistors, contacts

Hardware: wrenches, cutting tools

Manufacturing: dies, tools, bearing surfaces

Pyrotechnics: explosives, flares

Department of Materials Engineering at Isfahan University of Technology

Cermet cutting tools

(Ceramic-Metal composite)

www.kyocera-yashica.com.br

www.moldmakingtechnology.com

Microstructure: ceramic particles in metal matrixCermet-tipped saw blade for long life

Cermet cutting inserts for lathe

Powder Metallurgy Examples

Department of Materials Engineering at Isfahan University of Technology

Porous Metals

Oil-impregnated Porous Bronze Bearingsnic.sav.sk

www.hd-bearing.com

www.ondrives.com

Metal filters

Powder Metallurgy Examples

Department of Materials Engineering at Isfahan University of Technology

Forged P/M on right

Powder Metallurgy:

Connecting Rods

Powder Metallurgy Examples

Department of Materials Engineering at Isfahan University of Technology

Powdered Metal

Transmission

Gear

• Warm compaction method with 1650-ton press

• Teeth are molded net shape: No machining

• UTS = 155,000 psi

• 30% cost savings over the original forged part

www.chipm.com

Powder Metallurgy Examples

Department of Materials Engineering at Isfahan University of TechnologyDeGarmo

Powder Metallurgy Examples

Department of Materials Engineering at Isfahan University of Technology

Enhanced Materials Properties and

Performance

Challenges

for the future