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