Ceramic and Bearings:
Advanced ceramic materials were initially used in the early-60’s, mostly as
coatings on power turbines and electrical generating equipment. The hardness,
electrical resistance, and light weight of the material made them ideal for
these applications. Not long after that, advanced ceramic materials began to be
used as man-made abrasives. Today they are used in a number of common products,
yet most don’t even recognize them.
Now when I say ceramic,
I’m not talking about the same type that is used in your grandmother’s china.
I’m talking about industrial ceramics – typically made from compounds of
synthesized powders which are joined under extremely high pressure and heat.
(In fact, many closely resemble natural sapphire and ruby, and advanced ceramics
have a harness that approaches diamond.) Besides, a table setting of fine
dishes made from industrial ceramics would cost millions of dollars!
Industrial ceramics are
extremely resistant to wear, lighter than most metals, relatively strong, and
are corrosion resistant. If there was anything bad to say about them, it would
be that they will brittle fracture under stress, if there are surface pores,
cracks or flaws from the manufacturing process. That was the problem with early
ceramics used in industrial applications, but that was a long time ago – and no
matter what you’ve heard, most manufacturing processes have been improved to
mitigate fracture defects, since that time!
Industrial ceramics began
to be used for bearing materials when the need for alternatives to special
corrosion resistant metals was identified by the chemical industry. Initially,
stainless steel balls were coated with ceramics, and later manufacturing
processes were developed to produce totally ceramic balls. Today, you can even
get bearings that are completely made from ceramic – but they are quite
expensive and aren’t always available in the sizes you need for a reel.
Hybrid ceramic radial ball
bearings usually have metal (e.g. 440C Stainless Steel) races, cage, and
shields, with either completely ceramic or ceramic coated stainless steel
balls. (Except for the balls, most other components are manufactured as
described in the previous bearing tutorial.) They are relatively cost effective,
since the balls are the only incremental expense, when compared to stainless
bearings. They weigh approximately 40-60% less than their stainless steel
Ceramic and ceramic coated
balls typically have a surface finish that is 5 times finer than stainless steel
balls, so wear of the races and cages are significantly reduced, and bearing
lifetime typically increases (with lubrication) up to 5-10 times longer than an
all-stainless bearing. Although ceramic balls can be used without lubrication,
you can extend the fatigue life of the metal components with lubrication.
Lubrication also mitigates corrosion of the metal components (but more on that
later), since ceramic balls will not corrode.
Ceramic balls can be
fabricated so they are extremely uniform in size (diameter) and roundness. It
is not unusual for the balls in a bearing to all be within +/- 1 micrometer in
diameter, and +/- 0.1 micrometer in individual roundness! So, it’s no wonder
that much less ball slip and friction is produced, given the very fine surface
finish and uniform balls. Most ceramic hybrid bearings are at least ABEC 3 or
higher, primarily because of the stainless steel components!
Because all-ceramic balls
weigh roughly 60% less than a stainless steel ball, the bearing will have
reduced centrifugal loads as the balls spin against the races and cage. Reduced
centrifugal loads combined with the reduced slip, results in higher attained
speeds and less bearing vibration and noise. Although they can sound a little
rough when new or after cleaning, they should quiet down after the lube has had
a chance to disperse and run-in. However, one of the downsides with lighter and
more precise bearings is that they can be significantly affected if over-lubed
or get fouled with debris and/or water, due to the lighter ball weight, and
tighter tolerances and fit in the bearing. Debris may not be as readily cast
off, as it otherwise would, and instead will often circulate around inside the
bearing between races, balls, and the cage. Consequently, ceramic hybrid spool
bearings may need more frequent cleaning (when compared to lower quality
bearings), especially when used in a reel for shore fishing.
for making advanced ceramic materials are closely guarded by manufacturers. In
fact, the chemical composition for the trace and binding chemicals in the
Aluminum Nitride, Silicone Carbide, Silicone Nitride or Zirconium Carbide
powders is seldom disclosed, even to major customers. However, the basic
process is called ‘sintering’, which generally involves pressing the powder
slurry in a die under super-extreme forces, and then heating it to very high
temperatures to burn off oxides and unnecessary binding compounds. Some
companies have spent decades perfecting the process, so that pores, cracks, and
surface flaws are not introduced in the process. Especially since, a ball that
is manufactured with such defects could literally explode, even under light
Ceramic balls for bearings
(or coating for stainless steel balls) are also formed by sintering, but they
are made slightly larger than the final size. Diamond slurry mechanical lapping
machines are used to achieve the finished size, and continuously lapping for up
to 2 months is not unusual for some ceramics. The same quality checks and
controls are used while making ceramic bearings to ensure the product meets
final specifications. In addition, process controls are often implemented to
detect any surface flaws.
Here’s a tip you can use
when you buy ceramic bearings for your reel, to help ensure you are getting what
you paid for. Although not necessarily “cast in stone”, you can consider these
items; ABEC 7 ceramic hybrid bearings and ABEC 5 and higher all-ceramic bearings
are not usually greased (although they may have a light coating of oil, to
preserve any stainless steel components); most ceramic materials will be white,
black (or dark gray), or green in color, so be sure to check the balls on
ceramic-hybrid bearings; the bearing will weigh about one-half as much as a
stainless steel bearing in the same size; and hybrid ceramic bearings typically
do not come with full-size pressed shields that cannot be removed, and usually
come with no shield(s) at all or with removable shields.
Here’s another tip, you
may find useful. Ceramic spool bearings will typically run quieter and with
less vibration, than conventional bearings in the same ABEC class. However, you
may notice more vibration or noise from the reel, as you cast or crank it.
Wait a minute, how can that be, especially if they run better? Here’s an
explanation: The noise/vibration could actually be due to several factors, which
are really related to the higher spool speed, and much more braking action that
occurs during a cast. Some spools, reels and brakes may not operate as smoothly
at the higher speeds (since they may not be finely tuned, balanced or aligned,
as they could otherwise have been). Lastly, the vibration/noise may be due to
debris, excess or dried oil, or water that has fouled the bearing, causing noise
to be amplified while vibration is transmitted to the frame (especially on large
and more-open magnesium framed reels). The advantages of ceramic hybrid spool
bearings may not be very discernable to an occasional angler, but ask one who
spends a lot of time on the water, and they’ll probably tell you that they cast
just as far as regular bearings – but with less effort (and maybe even a little
further too)! It should also be pointed out, that the braking system on some
low-quality bait casting reels may not be able to handle the speeds developed by
ceramic spool bearings, and overruns could occur!
I predict that more and
more ceramic bearings and other components will be used in factory reels,
especially those designated for use in salt water. Manufacturing advances will
steadily drop ceramics prices, and consumers will continue to demand more
performance from high-end reels in the future. The TD-Z and a few other reels
already have ceramic spools, and Shimano, Daiwa and Okuma have supposedly been
putting “super corrosion resistant” (ceramic?) bearings in recent reels.
Who know, maybe 100 years from now, fishing reels won’t even have brakes or
drags – but will instead employ nano-ceramic bearing technology to brake and
play line? Ceramic is the new “Holy Grail” for fishing reels!
Reel Bearing Corrosion:
Stainless steel is pretty good at resisting corrosion in most environments.
However, when you use them in a bearing, the stainless has to be heat treated to
increase the surface strength of the metal. And there's the problem – the
corrosion resistance of stainless steels decreases during heat treatment,
because the structural composition of the metal has physically been changed, and
it is no longer passive to corrosion. Over time in the wrong environment, the
surface of most heat treated stainless steels can roughen, pit and generally
degrade. It can even cause the metal to completely crack and fail if the
stainless is under much stress (either from manufacture or from loading).
Stainless steel bearing components are no exception, especially in a high sodium
or chloride environment (i.e. saltwater).
approximately 3.5% of various salts by weight. The most predominate salt is
Sodium Chloride, and there are smaller amounts other salts also present. Salts
dissolve in water, to form ions which are loosely held by the water molecules.
However, the bond with the water molecules will easily break, allowing the ions
to affect other metals that may also be in contact with the saltwater (e.g.
Sodium and Chloride are
especially troublesome for Iron containing metals, including common heat treated
stainless steels used in bearings (which is usually made from 440C stainless
steel.) Several different types of corrosion can occur on the stainless, and
most will cause pits, blistering, and cracks to form from the surface into the
metal. If left in contact with seawater, the stainless bearing metal can
eventually fail, or may run rougher or cause problems with other metal reel
components. Balls and bearing races are especially vulnerable, since rotation
causes rubbing, which prevents their surface from forming a more stable oxide
layer that would otherwise protect them from attack. [Heat treated stainless
steels that don’t rub, generally don’t tend to be attacked as much by sea water,
because of this stable oxide layer.]
What about brackish
water? “Brackish water” contains dissolved salts in concentrations from .3% to
3.5%, and is not suitable as a normal source for drinking water. (“Fresh water”
contains less than .3% dissolved salts.) Brackish water is usually found near
sea water, and a few examples include salt water marshes, coastal inland
lagoons, and even some deltas. Brackish water can also include some recovered
Phosphate pits (like those found in Florida and other parts of the country),
which can also have high concentrations of Sodium based salts. The bad thing
about brackish water is that it also can contain high concentrations of microbes
and other chloride based organisms, which can also attack the carbons in steels,
especially metals under stress due to manufacturing processes. So, it is best
to treat brackish water like seawater, and carefully wash your reels in a spray
of warm tap water after fishing, and only use reels that are recommended for
Freshwater can still
contain small amounts of salts, algae and microbes that would otherwise attack
stainless steels, but the concentrations are typically so low that the attack
rate is usually measured in years, rather than days (like in seawater). Even
so, it may be a suitable practice to rinse your reels in warm tap water and dry
them after use, especially if a major algae bloom is in progress on the water
you have just fished. [The algae can live and grow in a reel (if they are in
sufficient quantity and left undisturbed in puddles of water), and the chlorides
left by the algae can attack bearings and other reel metals over a couple week
period.] However on a freshwater lake under normal conditions, it is probably
only necessary to shake out any water and dry the reel off, before storing in
your rod locker.
Be sure to periodically
check that drain holes are open and will drain any water or moisture from the
reel. Some reels have drains on the bottom sides of the reel where a handle or
palm plate attaches to the frame, and they can get plugged with debris, grease,
or corroded, allowing pockets of water to form in the reel.
What about chrome plated
and bearings made out of other materials?
Reel manufactures have
made bearings and bushings out of many different materials over the years.
Brass, bronze, and other copper alloy bearings were used early on. However,
they wore quickly and required frequent lubrication, but were fairly resistant
to corrosion. Carbon steel was also used for reel bearing materials, and
although it wore better, it was extremely susceptible to water corrosions and
required constant cleaning and other care.
Chrome steels were
initially used to plate softer bearing materials, in order to improve the
surface finish and reduce wear. The Chromium, Manganese and Silicone in the
steel makes the surface more durable than plain brass, bronzes and carbon based
steels, and chrome has fair corrosion resistance if alloyed with Nickel. Chrome
can also be polished to provide a good surface finish, with moderately low
friction from slip. However as plating, it can blister, chip and flake off,
which exposes the underlying metal to wear or corrosion.
Solid chrome steel is
actually a form of stainless steel if nickel is present, and it resists
corrosion fairly well, but is not very durable (can wear poorly, gall and even
crack). Without the nickel, it is much more durable, but is not as corrosion
resistant. Even so, some lower end reels are still being manufactured with
chrome steel bearings and other components. The key is to keep them well
lubricated, and dry while in storage, and rinse them immediately after use in
saltwater. Some alloys of chrome steel resist saltwater corrosion better than
others, so following manufacturer recommendations on use and maintenance is
advisable. A few anglers have reported good success with the use of spray or
gel moisture blockers, to protect against seawater contacting the outer races on
chrome bearings and other metal reel parts. Beoshield T-9 and similar
products contain anti-corrosion, rust prevention, and metal protectants, that
supposedly last for months, in a fishing reel. Although I have not personally
used Beoshield, I have seen it at several marine dealers.
Reel and bearing
manufactures have dealt with the effects of corrosion on bearings in a number of
ways. In fact, it is not uncommon to see combinations of the following used in
a modern high end reel: