Alu-coated
Piston Rings
Typical appearance of an alu-coated top piston ring for
Cross section of an alu-coated piston ring. The yellow
an MA N B&W MC engi ne
bronz e is clea rly visi ble a long with the b lack alumi na oxides
Al u- co at is a br on ze -b as ed co at in g wi th
Retrotting benets are multiple
alumina oxide insolubles, it was developed
Not only does alu-coat eliminate the piston
in the late 1990s to shorten the running-in
ring running-in time when tted in a previ -
time of new MAN B&W MC engines.
ously used liner. The coating also offe rs an extra safety margin when dealing with op-
MAN Diesel introduced alu-coat based on
erational problems. This proces s normally normally
its effective running-in features for honed
takes 500 to 2,000 hours (depending on the
and semi-honed liners. A wealth of experi-
conditions).
ence and a 100% success rate set alu-coat apart as the no. 1 running-in coating choice.
Th e slig sl ig htl y abra ab rasi si ve ef fect fe ct of alual u- coate co ate d
Alu -coat -c oat red uce s sho p tri al tim es and crecre -
piston rings makes them very suitable when
ates a safe and reliable running-in period.
changing worn piston rings in connection
Today, alu- coated coate d rings r ings are used in n ew ene n-
with piston overhauls. A liner which has
gines as well as for retrot in older engines
been operating with worn rings normally
with honed and semi-honed liners. Alu-coat
shows signs of blow by lacquer marks and/
also reduces the cylinder oil consumption
or local bore polish. Alu-coat contributes to
during running-in.
some running-in liner wear on a micro scale, wich is normally enough to re-establish the
The right prole for the job
important open-grain structure of the liner
Alu -coat -c oat is a sem i-s oft, of t, the rma lly spr ayed
that is vital for the tribology of the liner/oil/
coating, approximately 0.25 mm thick. It comes ‘as sprayed’, which gives a somewhat rough appearance, but forms a sm ooth, proled running surface very rapidly.
Th e soft so ft matr ma trix ix at th e coati co ati ng allo al lows ws th e hard insolubles to protrude onto the running surface of the rings and act in a slightly abrasive way on the running surface of the liner. The matrix also serves as a safety buffer that prevents initial scufng problems
until running-in is complete.
piston ring system.
C o C p o y p r i g y r h i g t h © t © M A M N A D N i e D s i e s l e · l S · u S b u j e b c j e t c t o t t m o o m d o i f d i c i a f i c t i a o t n i o i n i t n h e t h i e n t i e n r t e e s r e t s o t f o t e f c t e h c n h i c n a i c l p a l r o p g r o r e g s r e s s . s .· 3 · 0 3 1 0 1 0 0 0 0 1 0 8 0 0 p 1 p p r p M r m J a m n 2 0 X 1 X 0 P r i n t e d i n D e n m a r k
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