Repel vs Attraction:
I have found out that attractive mode is greatly stronger than repulsive mode. Look at this link.
http://www.magnetsales.com/Design/Calc_filles/PullAndPushBetween2RectMagnets.aspNow there isn't any doubt any more whether the force of repelled magnets are stronger or weaker.
Demagnetizing myth:
The demagnetizing force of Neodymium magnets is approx 1400 KA/m which is far far greater than the force of
two neo magnets in repel mode. Therefore cannot two neodymium magnets in repel get demagnetized.
More info found at this site:
http://www.themagicroadshow.com/wizardmagnets/html/technical_info.htmlA neodymium magnet will lose 1% of it?s magnetism every 10 years.
Neodymium magnets lose 0.12% of their magnetism per degree rise in temperature.
This is not a permanent loss. The magnet will recover it's magnetism on cooling.
Neodymium magnets must not be exposed to temperatures in excess of 80 degrees C because they
will not recover all the lost magnetism on cooling if the 80 degrees limit is crossed.
However, there are special grades of neos hat can handle up to 200 degrees C instead of just 80C.
Neodymium magnets get more powerful as they get colder!
The density of Neodymium magnets (weight) is 7.5 g / cm3.
Force example of Neodymium Magnet N42 at 25mm dia x 10mm:
Pull force in contact with mild steel is 16 kgs
Pull force generated by two magnets attracting each other is 54 kgs
Repulsion force generated by two magnets in repel is 33 kgs
By request:
Never let any neo magnets smash into each other from a distance and
don't let a magnet smash into solid iron. This will crack them into pieces.
Don't even let them attract together from a small distance. This will
shatter tiny pieces from the edge of the magnets and they become weaker.
Ones the protective seal on a neo magnet is broken moist can easily enter
the magnet and rapidly destroy it. Seal the broken area with thin epoxy.