responding to
http://www.homeownershub.com/mainten...io-228602-.htm
biguggy wrote:

Why is anyone surprised that bearings fail in these machines?
I have serious reservations about the adequacy of these bearing
arrangements with out taking into account the following
The spiders in these machines are manufactured from aluminium alloys,
which are capable of being corroded by almost all laundry aids used,
including HE detergent, should the required concentrations be reached. The
product of this corrosion is aluminium oxide, the same very hard gritty
‘stuff’ that is the ‘grit’ on the orange coloured sandpaper. Now most of
this aluminium oxide will adhere, very strongly, to the spider: A very
small percentage will be dissolved in the ‘water’ and some will be carried
in suspension in the ‘water’ making a very effective grinding paste. In my
opinion the soft lips of the shaft seal stand very little chance once this
occurs with the result that the seal fails allowing ‘water’ into the
bearings which destroys the bearings in two ways, the normal corrosion of
steel in water and the added destructive power of the ‘grit’ abrading the
bearings.

Many posts on many sites claim that the corrosion of the spiders is due to
galvanic action. I do not agree, I believe it is primarily chemical
corrosion.

Should the corrosion have been galvanic between the stainless steel drum
and the aluminium spider the majority of the corrosion would have been at
the junction of the two metals i.e. at the ends of the arms. I have seen
no photographs of spiders corroded in such a manner, nor read of any
similar descriptions.

Aluminium, and its alloys are corroded when immersed in an aqueous
solution with a pH value above about 8.0 or below about 4.0 (nitric acid
is a well known exception). All detergents have to be above about 8.0 or
they would not work. The Material Safety Data Sheets put out by Proctor
and Gamble state that the pH for one of the liquid ‘Tides’ is 8.0 and for
one of the ‘Tide’ powdered detergents as 11.0. Bleach, (sodium
hypochlorite) is also very corrosive to aluminium. I should add that for
corrosion of the spider to take place these levels are considerably above
the levels found in a washing machine during the wash/rinse phases of the
cycle.

Sodium carbonate (washing soda) and sodium percarbonate found in some
laundry aids (Affresh and Oxi-Clean [powder]) are also corrosive to
aluminium, as is borax, provided the required concentrations are reached.

I believe the mechanics of the corrosion are as follows.
Even after the fastest spin small quantities of water will remain on the
shaft and towards the centre of the spider. Any recesses in the spider
close to the centre will aggravate this situation. This water will contain
‘contaminants’, unused detergents and other laundry aids used, soil from
the laundry, products of the reactions between the laundry aids used and
the soil from the laundry, chemicals contained in the tap water used and
the products of any reactions between these chemicals, the soil and the
laundry aids used. Should sufficient of these ‘contaminants’ be present
the pH of the mixture can, as evaporation takes place, rise to a level
where corrosion will take place.

Corroded spiders can be seen at: -

http://fixitnow.com/wp/2009/10/28/fr...tallic-misery/

http://softsolder.wordpress.com/2010...-drum-the-rot/
for a LG spider
http://www.viewpoints.com/LG-TROMM-F...-review-33dc10

For information on galvanic corrosion there is a very good paper at: -
http://www.unene.ca/un1001/UN1001_Ga...0Corrosion.ppt

For information on chemical corrosion of aluminium (or ‘micro galvanic
corrosion as the author calls it, I grew up calling it ‘pitting corrosion)
there is an informative paper at:
-http://www.sintef.no/static/mt/norlight/seminars/norlight2003/Postere/Gaute%20Svenningsen.pdf