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CermiNil™ Process: A nickel
alloy cylinder bore coating from Engine Components, Inc.
 »
CermiNil™ Process vs. Nitrided Steel
» Ring Finish
and Break-In
» Environmental
Considerations
» Wear Rate vs.
Coating Cross Section
» Chrome
vs. Nickel
» More Repairable
Cylinders
» Identification
of the CermiNil™ Process
» Head and
Barrel Interface
» Piston Rings
for CermiNil™ Process Cylinder Bores
» Limited Warranty
» Engine Certification
» The CermiNil™
Process
Other Nickle Process Resources:
» Nickel+Carbide™ Coated Bore
» Nickel Bore Rejuvenation
Kits
CermiNil™ Process
vs. Nitrided Steel
The CermiNil™ process is both, an OEM process and a repair process.
As an OEM process, it is used in new products by many of the world's leading
engine manufacturers like Ford, Mercedes, Suzuki, Porsche and others.
ECi incorporates the CermiNil™ process as an option in its line of new
Classic Cast cylinders. As a repair, the CermiNil™ process offers the advantage
of restoring the cylinder bore dimensionally allowing the salvage of worn
or rusted bores. Either as an OEM or as a repair process, the CermiNil™
process results in a cylinder bore that is far better than a nitrided
bore. The most obvious advantage is in corrosion protection. The natural
corrosion resistance of nickel differs greatly from nitrided steel's affinity
to corrosion. Additionally, the CermiNil™ process provides a surface which
is uniform throughout as opposed to nitrided steel which is a case-hardened
surface that varies in hardness along its depth and can show soft spots.
These soft spots lead to uneven and premature wear.
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Ring Finish and Break-in
Break-in of a CermiNil™ process cylinder is unique and cannot be compared
to any other cylinder bore/ring combination. The smooth surface of the
CermiNil™ process bores produces reliable ring break-in, which is especially
significant when installing new rings during cylinder mid-life. A normally
run CermiNil™ process cylinder bore surface without any surface roughening
will accomplish ring break-in equally as well as a new cylinder. Run-in
procedures are specified in the ECi handbook entitled "Break-in Instructions".
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Environmental Considerations
ECi GOES GREEN! Laboratory research has shown
that the chromium chemical used in the chromium plating process is a carcinogen.
While the resultant metal coating poses no hazard while it is in the engine,
disposing of waste from the plating process as well as disposing of the
grinding debris from the cylinder overhaul process is becoming more difficult
and costly. The cost of disposing of chromium waste is expected to rise
dramatically in the future. By contrast, waste management costs associated
with the CermiNil™ process are affordable now and are expected to stay
at present levels well into the future, thereby insulating the customer
from pass-through disposal costs.
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Wear Rate vs. Coating Cross
Section
CermiNil™ process excepted, all cylinder bore surface treatments currently
approved for use in aircraft piston engines have the common characteristic
of exhibiting increasing wear rates as the bore enlarges due to the effects
of friction. As the chart indicates, the beneficial features present on
the surface of a new cylinder bore begin to diminish as the cross sectional
thickness is reduced. Lubrication is reduced during periods of high cylinder
temperature as well as high power settings. Therefore, once lubrication
between piston ring and cylinder bore deteriorates and friction begins
removing metal from the bore, wear rates will irreversibly begin to climb,
resulting in an extreme ring step.
The CermiNil™ process, on the other hand, has a uniform composition throughout
its entire cross section, meaning that any short-term increase in wear
rate due to reduced lubrication is temporary and wear rate will return
to normal when lubrication normalizes.
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Chrome vs. Nickel
Chrome and nickel have many similarities but also one important difference.
The two metals are similar in the sense that they can be plated on steel
with excellent adhesion. The use of chromium for building up worn cylinder
barrels has a long and successful history. Both nickel and chromium are
very corrosion resistant and can be removed and replated multiple times.
An important difference is that nickel is oil wettable and chromium is
not.
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More Repairable Cylinders
It is not uncommon for used cylinders to have barrels that can not be
saved by grinding oversize or by plating back to standard. Excessive corrosion
and wear as well as physical damage to the cylinder barrel make some cylinders
non-repairable. The historical fix for this condition is to rebarrel with
a new forging which may not be cost effective. The proprietary technology
incorporated into the CermiNil™ process includes a certificated method
which permits most cylinder barrels and heads to be selectively fitted
to mating parts other than the originals. Therefore, a barrel with a non-repairable
defect can be discarded and replaced by a used or new barrel. This valuable
service can be provided for a small additional cost.
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Identification of the
CermiNil™ Process
The coating produced by the CermiNil™ process can be identified by its
color, texture, by performing the copper sulfate test on it or by the
silver color painted on the flange of the cylinder. With regard to color
of the coating, nickel usually has a yellow tinge when it is finished
to a low Ra. However, alloy steel can also have a yellow tinge when highly
finished. Polished chrome, on the other hand has a bluish tinge. The copper
sulfate test is the most reliable method of differentiating the CermiNil™
process from a steel bore. Copper sulfate solution applied to a steel
cylinder bore will turn the steel to a copper color (nitrided steel reacts
slowly, so be patient). Copper sulfate applied either to a chrome bore
or a CermiNil™ process bore produce no change in color. The texture (surface
finish) of the CermiNil™ process is smooth by comparison to a traditional
ring finish for steel. Except for loss of cross hatch, there is very little
difference in appearance between a new CermiNil™ process cylinder bore
and a cylinder bore with several hundred hours of operating history. Externally,
the area of the cylinder which normally receives a color code to indicate
the type of cylinder bore material, will be painted with two (2) silver
bands. A teal color painted between the bands indicates that the head
has been treated with the IFR process.
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Head and Barrel Interface
The CermiNil™ process cannot be performed on a cylinder barrel which is
assembled on an aluminum head. Therefore, all cylinders will be non-destructively
disassembled before processing by using an FAA approved proprietary process
which has many years of successful field experience.
A major benefit resulting from disassembly is the ability to inspect
all hidden surfaces including the threads on both the aluminum head and
the steel barrel. This procedure fully meets the requirements of FAR 43.2.
Using dye penetrant inspection on the aluminum threads and magnetic particle
inspection on the steel barrel allows ECi to make a higher level of airworthiness
assessment on a used cylinder than anyone else in the industry.
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Piston Rings for CermiNil™
Process Cylinder Bores
The CermiNil™ process has been FAA approved to operate with a molybdenum
faced top compression ring and flake-graphite cast iron rings in the remaining
positions. This combination provides optimum results with reliable break-in
and increased durability.
The ring sets for CermiNil™ process bores are designated as "CN"
ring sets and are sold exclusively by ECi. To order CN ring sets contact
ECi Customer Service at 1-800-ECi-2FLY (800-324-2359) or e-mail us at:
sales-service@eci.aero.
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Limited Warranty
ECi warrants a cylinder bore treated with the CermiNil™ process against
corrosion and or premature wear for five years or TBO, whichever comes
first. Under this warranty, ECi will reprocess any normally run cylinder
bore which exhibits corrosion or wear beyond service limits within the
warranty period and include a new set of rings, all at no charge.
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Engine Certification
The CermiNil™ process is certified (STC SE8776SW) for use on any aircraft
piston engine. Processing capability is subject to availability of tooling
and bore dimensions. Contact the factory for additional information at
1-800-ECi-2FLY (800-324-2359).
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The CermiNil™ Process
A nickel alloy cylinder bore coating from Engine Components, Inc. CermiNil™,
IFR, Airmotive Steel and Classic Cast are trademarks of Engine Components,
Inc. ©2000 ENGINE COMPONENTS, INC.
» TOP
Other Nickle Process Resources:
» Nickel+Carbide™ Coated
Bore
» Nickel Bore Rejuvenation Kits |