Date post: | 05-Apr-2018 |
Category: |
Documents |
Upload: | mohamed-gamil |
View: | 221 times |
Download: | 0 times |
of 27
8/2/2019 Powder Metal Manufacturing
1/27
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
2/27
PMreferstoarangeofmanufacturingandmetal
formingpractices
that
are
used
to
produce
net
or
nearnetshapepartsfrommixturesofmetaland
alloypowders
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
3/27
3000B.C.
Egyptians
made
tools
with
powder
metallurgy
1900stungstenfilamentforlightbulb
1930scarbidetoolmaterials
1960sautomobileparts
1980saircraft
engine
turbine
parts
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
4/27
Abilityto
create
complex
shapes
Highstrengthproperties
Low
material
waste Goodmicrostructurecontrol
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
5/27
TABLE 17.1
Application Metals Uses
Abrasives
Aerospace
Automotive
Electrical/electronic
Heat treating
JoiningLubrication
Magnetic
Manufacturing
Medical/dental
MetallurgicalNuclear
Office equipment
Fe, Sn, Zn
Al, Be, Nb
Cu, Fe, W
Ag, Au, Mo
Mo, Pt, W
Cu, Fe, SnCu, Fe, Zn
Co, Fe, Ni
Cu, Mn, W
Ag, Au, W
Al, Ce, SiBe, Ni, W
Al, Fe, Ti
Cleaning, abrasive wheels
Jet engines, heat shields
Valve inserts, bushings, gears
Contacts, diode heat sinks
Furnace elements, thermocouples
Solders, electrodesGreases, abradable seals
Relays, magnets
Dies, tools, bearings
Implants, amalgams
Metal recovery, alloyingShielding, filters, reflectors
Electrostatic copiers, cams
Source: R. M. German.
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
6/27
Afabricationtechniqueinvolvesthecompactionofpowderedmetal,followedbyaheattreatmenttoproduceamoredensepiece.
Powdermetallurgyisespeciallysuitableformetals havinglowductilities havinghighmeltingtemperatures
Powder Metallurgy
pressure
heat
point contactat low T
densification by diffusion athigher T
areacontact
densify
Production of P/M Parts:
Preparation of Metal Powders
Compaction (pressing)
Sintering (densification) atelevated temp.
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
7/27
Figure 17.1 (a) Examples of typical partsmade by powder-metallurgy processes. (b)Upper trip lever for a commercialirrigation sprinkler, made by P/M. This
part is made of unleaded brass alloy; itreplaces a die-cast part, with a 60%savings. (c) Main-bearing powder metalcaps for 3.8 and 3.1 liter General Motorsautomotive engines..
(a)
(b)
(c)
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
8/27
Outline of processes and operations involved in making powder-metallurgy parts.
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
9/27
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
10/27
Figure 17.3 Particleshapes in metal
powders, and theprocesses by whichthey are produced.Iron powders areproduced by many ofthese processes.
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
11/27
Scanning-electron-microscopy photograph of iron-powder particlesmade by atomization. (b) Nickel-based superalloy (Udimet 700)powder particles made by the rotating electrode process; see Fig.17.5b. Source: Courtesy of P. G. Nash, Illinois Institute ofTechnology, Chicago.
(a) (b)
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
12/27
Methods of metal-powder production by
atomization; (a) meltatomization; (b)atomization with arotating consumable
electrode.
Methods of mechanicalcomminution, to obtainfine particles: (a) rollcrushing, (b) ball mill, and
(c) hammer milling. Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
13/27
Some common equipment
geometries for mixing orblending powders: (a)cylindrical, (b) rotatingcube, (c) double cone, and(d) twin shell. Source:Reprinted with permissionfrom R. M. German,Powder Metallurgy Science.Princeton, NJ; Metal
Powder IndustriesFederation, 1984.
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
14/27
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
15/27
(a) Compaction of metalpowder to form abushing. The pressedpowder part is calledgreen compact. (b)Typical tool and die setfor compacting a spur
gear. Source: MetalPowder IndustriesFederation.
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
16/27
TABLE 17.2
Metal
Pressure
(MPa)Aluminum
Brass
Bronze
IronTantalum
Tungsten
70275
400700
200275
35080070140
70140
Other materials
Aluminum oxideCarbon
Cemented carbides
Ferrites
110140140165
140400
110165
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
17/27
Pressing is done underhigh pressure
A 7.3 MN (825 ton)mechanical press forcompacting metal powder.
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
18/27
Figure 17.12 Schematic diagram of cold isostatic pressing, as applied toforming a tube. The powder is enclosed in a flexible container around asolid core rod. Pressure is applied isostatically to the assembly inside ahigh-pressure chamber. Source: Reprinted with permission from R.M.German, Powder Metallurgy Science. Princeton, NJ; Metal Powder
Industries Federation, 1984.
Figure 17.14 Schematic illustration of
hot isostatic pressing. The pressure andtemperature variation vs. time are shownin the diagram. Source: Preprinted withpermission from R.M. German, Powder
Metallurgy Science. Princeton, NJ; MetalPowder Industries Federation, 1984.
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
19/27
Figure 17.15 An example ofpowder rolling. Source:Metals
Handbook(9th ed.), Vol. 7.
American Society for Metals.
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
20/27
Figure 17.9 (a) Density of copper- and iron-powder compacts as a function of compacting pressure. Density greatlyinfluences the mechanical and physical properties of P/M parts. Source: F. V. Lenel, Powder Metallurgy: Principles and
Applications. Princeton, NJ; Metal Powder Industries Federation, 1980. (b) Effects of density on tensile strength,elongation, and electrical conductivity of copper powder. IACS means International Annealed Copper Standard for
electrical conductivity.
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
21/27
Figure 17.16 Schematic illustration of two mechanisms for sintering metal powders: (a) solid-state materialtransport; (b) liquid-phase material transport. R = particle radius, r= neck radius, and = neckprofile radius.
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
22/27
Examples of P/M parts, showing Bestdesign Practice.Note that sharp radii and reentrycorners should be avoided.
Threads and transverse holes have tobe produced separately by additionalmachining operations.
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
23/27
TABLE 17.5
Process(*)
Density
(%)
Yield
strength
(MPa)
Ultimate
strength
(MPa)
Elongation
(%)
Reduction
of area
(%)
Cast
Cast and forged
Blended elemental (P+S)
Blended elemental (HIP)
Prealloyed (HIP)
100
100
98
> 99
100
840
875
786
805
880
930
965
875
875
975
7
14 40
8
9
14
15
14
17
26
(*) P+S = pressed and sintered, HIP = hot isostatically pressed.
Source: R.M. German.
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
24/27
Usesasintering
atmosphere
and
asintering
furnace
Theatmospheretransfersheattothecompacted
powder,adjustsimpuritylevelsandremove
lubricants.
Atmospherecanbepurehydrogen,nitrogenor
ammonia.
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
25/27
TABLE 17.3
Material
Temperature
( C)
Time
(Min)Copper, brass, and bronze
Iron and iron-graphite
Nickel
Stainless steels
Alnico alloys
(for permanent magnets)Ferrites
Tungsten carbide
Molybdenum
Tungsten
Tantalum
760900
10001150
10001150
11001290
12001300
12001500
14301500
2050
2350
2400
1045
845
3045
3060
120150
10600
2030
120
480
480
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
26/27
TAB LE 17.6
W eight (kg)
Potential
cost
Part
Forged
billet P/M
Final
part
saving
(% )
F-14 Fuselage brace
F-18 Engine mount supportF-18 Arrestor hook support fitting
F-14 Nacelle frame
2.8
7.779.4
143
1.1
2.525.0
82
0.8
0.512.9
24.2
50
2025
50
Mohamed Gamil
8/2/2019 Powder Metal Manufacturing
27/27
Mohamed Gamil