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Special feature
PM users say what they want Cost savings and greater functionality in PM products are high on the 'must have' list for large manufacturers and their major suppliers, and they said so at a symposium held at Bremen in Germany. Bernard Williams was there...
D Es],l[l< the continuing sluggish- ness in the German economy;
and tile general downturn in
car sales and production among German car manufacturers ill 2002,
the 220 delegates attending the 21st PM Symposmnl and Exhibition in Hagen,
Germany (November 28-29) were m a con-
fident mood for the furore prospects for powder metallurg> The positive atmos-
phere was created not only by some excel- lent review presentations in the technical programme showing the breadth and depth
of present day PM technology and the
man} branches of applications for PM
products, but also by some positive fore-
casts for PM. Thirty-six exhibitors filled the
available exhibition space with displays of
hardmetal products, metal powders, press-
cs, furnaces, PM tooling, testing equip- ment, and research projects at institutes.
Organised by the Fachverband
Pulvermetallurgie on behalf of the German
Gememschaftausschuss Pulvermetallurgie,
the Hagen Symposium has come to sym-
bolist the strength and unity of thc Germal3-speaking PM communitF
Professor Bernd Kieback, chairman of the
Gemeinschaftausschuss, said in his wel-
come to delegates that there are no less than 150 people active in the various working
groups of the Ausschuss which cover pow-
der production, sintering, metal injection
moulding, and process simulation. Seven important projects had already been com- pleted, the most notable among these being
the testing and collcction of mecha|fical alld d\rnaulic property data of PM steels
undertaken by Dr Morris Sonsino and his
team at the Fraunhofer I,BF in l)armstadt
in the 1980s. This data has proved invalu-
able in the right selection and application of
PM structural steels for high-performance
applications. In July 2001 a three-year pro- ject was started on the "Sinter-hardening of
PM steels". This is being co-ordinated by
the Technical University Karlsruhe. Dr Hans-Peter Koch, recipient of the
2002 Skaupy Prize, gave a keynote presen- tation in which he outlined some of the
2~
PM Purchasing at Bosch (Global) ~106 Million
4% 5%
I 50% 56%
PM ports and bearings purchasing at Robert Bosch GmbH has increased [TOm ~7 million to #Jo6 million over the post 2o years.
PM extruded storter geor and its microstructure at high density - 7.7 g/crrP - double its normally expected [otigue toughness,
2/4 February 2003 metal-powder.net
Special feature
10
i
], +tinal dlmlilltclllt~ i ~ r o ~ Warm compacted + HT-sintered
. . . . . . . . bimodal powder + HT-slntered
conventional PM steel
0 . . . . . . . . . . . . . . . . . .
1 1000 1000000
~ / N
Warm compacted and post-sinter densiped PM steel gear matches properties of wrought steel.
developments which have helped to
expand PM applications in recent )'ears -
making it a key nlanufacturing technology
at Robert Bosch GmbH. He also gave
some pointers as to what the PM industry
needs to do to achieve future growth.
Dr Koch said that most of PM's growth
over the past 20 years has been through the
introduction of a wider range of PM materi-
als, tremendous increases m mechanical
properties, and through the creation of a
greater understanding by user companies of
PM's capabilities. This has resulted in the
purchase of all PM products at Bosch to
increase to (7106 million in 2002 with struc-
tural PM parts taking the lion's share.
"Original equipment manufacturing (OEM)
companies such as Bosch, which is also a
Tier 1 system supplier to the automotive
industrB are ahvays looking for greater func-
For PM to be the materials technology for the new Millennium Dr Koch pre- sented delegates in Hagen with his "end-user" wish list. On the list are: - Increasing use of prealloyed powders
with improved compressibility and sinter-hardening capabilities as well as being "environmentally friendly";
• Close the "properties gap" with solid metallic materials;
• Wider range of tailored and multi- functional materials;
• Increase end-user confidence in the PM process;
• Use of property data banks for materials specifications; and
• Shortening of product development time and cutting development costs by use of simulation techniques.
tionalit b tailored properties and cost savings
in components and systems," said Dr Koch.
"PM has great potential in all these areas
and can offer end-uscrs considerable cost
savings due to the reduced number of pro-
cessing steps. The combination of cost sav-
ings, greater functionality and increasing
FRAN/ 8KAIII'Y was a m o n g a band of
PM pioneer~ who ahmg with Zapf,
Wicmcr, Kieffer, bilbcreisen, Hotop and
others promoted the post-war develop-
mentol powder metallurgy and created
a new ft,urn for community-based PM
research and collaboration in Germany.
Ftlis was eventually formalised rata
the Auschuss Pulvermetallurgie, which
in 1982 initiated the 8kaupy Prize. This
is given annually ill Hagen to those who
have made the greatest contributions to
the development and application of
PM. At the recent 2002 Hagen PM
Symposium tile Skaupy Prize was
bestowed on Dr. Hans Peter Koch, a
materials specialist at Robert Bosch
( ;mbH in Gerlingen, German.~:
l)r Koch joined Bosch in 1980 and was
given tht: task of evaluating and develop-
mg the potential for structural PM parts.
At that time Bosch purchased around (77
million of PM products annuall); 70 per
ccm of which were sintered bearings.
"Structural PM parts even as recently as
1980 had a poor image at Bosch," said Dr
Koch. "The quality of PM was unreli-
able, and through the rclativeh" high
porosity in structural parts mechanical
properties were lower compared with
machined parts." He made it his task to
work with PM suppliers to gradually
reverse this image through improvements
in quality and properties. He also under-
took to achieve a greater understanding
among the design engineers at Bosch as
to the potential of the PM process.
Over the past 22 )'ears PM usage in
Bosch DIY and garden appliances and
also automotive systems ]1as soared to
(7106 million annually PM structural
parts now take around 70 per cent of
this amount with sintered bearings :it 25 per cent and filters at 5 per cent. Dr
Koch can rightly claim much . f the
credit for this success as a champion t~>r
the PM process at Europe's biggest
OEM automotive supplier and Icadmg
producer of electrical power tools for
DIY and professional use.
Dr Hans Peter Koch, materials spe- cialist at Robert Bosch GmbH received the 2.oo2 Skaupy Prize [or his contribution to promoting PM.
( ) t he r recent %kaup~ Pri/c \~Jn ic'i-,
h~cludu Ih-ofcs~or \\aldenmr i~Ivr,nd,
lfirector (~f Iraunhof~.r ll~'.'h in
Dr~.sden 2000] . ~InJ l)r l l,ul> I)~-icr
lxunze, Director at l;raunhok.l II' ~,:\ I U,
lhcmcn m 2001. : \ r tKlc~ oi~ tl~c' I'M
research undcrtakL, n at IIA.\I :lnd Ikl~,
wi l l bc publ ished in tl~c' : \ l , i rc l anti
Apr i l 200 ~, issu<:. <>f th ' t<d I } , . .< ' . R,>l,ort.
m e t a l - p o w d e r . n e t February 2 0 0 3 ~ 2 5
Specia[ feature
Soft magnetic cores made from insulated iron powders ore used in Bosch diesel injection systems.
Bosch common mff diesel injection system.
end-user confidence in the strength and reli-
ability of PM products will create further
growth opportunities for the industry m the
future," he said.
lmprovcd mechanical properties, particu-
larly fatigue properties for high-performance
PM parts, werc said to be one of the keys to
PM's future success. Dr Koch referred to a
smtered gear (Fig.l) used in a Bosch starter
motor which he said had a bending fatigue
strength of 330 N/ram 2 when forward-
t'xtruded to increase density in the gear teeth
to 7.7 g/cm ~. This is double the fatigue
strength of the gear m the sintered condition
at 7.1 ~cm ~. Impact energy increased from
15,1/cln ~ to 120 J/cm ~, he said.
Higher green densities achieved by
warm pressing allowed machining of green
parts as well as gaining higher smtered
strcngth, and thc development of new
high-temperature sintering furnaces pro-
dtlced inore honlogeneotls microstructures
and m(~l'e rounded pores when sintermg
abovL. 1200<'(L Somc of these develop-
mcnts have helped switch applications to
PM at Bosch, said 1)r Koch. "For cxamplc,
tests on a gear used in a hydratllic pump
have shown that warm compacted parts
made from Fe-l.SCu-4Ni-0.SMo steel sin-
tered at high temperature, and with post
densification of the gear teeth, can com-
pete with the properties of 16MnCr5 solid
steels. The key to the success of this pro-
ject was the cost effective post-densifica-
tion of the gear teeth."
Another area of great interest to Bosch
is the new generation of soft magnetic
materials based on insulated iron powders,
said Dr Koch. A number
of PM soft magnetic cores
such as the one shown
above, are finding applica-
tions in the Bosch com-
mon-rail injection system
for diesel engines. This is
thanks to the higher densi-
ties and strength made
possible by warm pressing
insulated iron powders
which results in improved
magnetic properties. "The
new gencration insulated
Two types of PM magnetic materials are com- bined in this magnetic core.
iron powders has allowed for a reduction
in the size of the cores, an increase in their
functionality as well as giving a 50 per cent
cost advantage over machined or cast
parts," said Dr Koch.
Another approach is in the direction of
"multifunctional" components whereby
parts having different properties are com-
bined by a joining process or by diffusion
bonding during sintering. He gave the
example of a magnetic core (above) which
combines two PM materials - iron-phos-
phorus and a paramagnetic 18CrN12 in
the middle and at the base. A further
example is the combination of paramag-
net ic l8NiCrl2 PM steel and two sintered
AlNiCo magnets in two identical yokes
used in a car speed sensor (below).
Dr Koch said that in order for PM to
continue growing at end-user companies
such as Bosch, the PM industry needs to
make concerted efforts not only to educate
design engineers, but also the employees in
PM manufacturing and quality control.
Critical for the design engineers is the
availability of a broad range of property
data on fatigue and dynamic properties of
PM materials so that they can compare
this data with that already available for
competing materials.
26 February 2003 metal-powder.net