The bat-suit is one of the most highly advanced technological items in comics, the more so that it maintains an aspect of realism to it with the more contemporary aspects of technology and science applied to it.  There is of course still an aspect of fantasy, but the tech itself is a little misconstrued as well.  Here are a couple of reasons why.

Nomex/Kevlar Weave

Both of these materials are not exactly still considered new by today’s standards (Nomex has been around since the 1960s) but they are still used in a lot of apllications.  Nomex is still used by a lot of firefighters and Kevlar figures heavily into body armour.  What most don’t know is that they are chemically very similar, both being aramids similar to nylon.  What is not really of any value is weaving the two together as is usually described about the bat-suit.  The two materials work on the concept of their uniform nature – Kevlar is effective because its tensile strength along a horizontal surface is quite high, high enough to stop bullets, while Nomex is a poor conductor of heat.  The problem is mixing the two together is going to create a problem akin to trying to stop the wind with a screen door.  Assuming the fibers are woven one for one it means that that every second fiber is not designed to do what the overall effect desires.  I guess they could say that it was just layered, but that leads to another problem, that of suffocation.

Cowl armour

Magical Kevlar … there is nothing it can’t do.  Apparently by putting Kevlar in the cowl it makes Batman be able to be shot in the head.  That is not exactly how Kevlar helmets work though.  Kevlar does essentially one thing, it stops something from getting through by having a high friction on a perpendicular plane to its surface.  This eliminates the problem of penetration (which is an important one when it comes to most organs) but not of momentum.  A lot of people while wearing armour and if hit by a bullet will still get a broken ribs because the bullet’s momentum continues even if it doesn’t penetrate the material.  In the case of army helmets this means that the helmet has the ability to move around on the head somewhat to dissipate the shock.  In terms of a skin tight helmet this would be mostly useless.  It might stop the bullet, but the momentum would probably still result in skull fractures and concussions. 

Are you getting all of this from Batman Begins/The Dark Knight, where it's said that Bruce can't be shot in the head or he'll die, and where after being shot in the ribs, he is greatly injured?  

Batman fixes all this with push ups.

@Daveyo520: And he can breathe in space

Now this was quite informative. I mean I was aware of the mixtures in the armor of his suit but have been very vague on the problems that would arise from it. Good job. I like this.

never really looked into this before...good insight yet again!

maybe the under layer is made of nomex and the outer armor looking areas are made of kevlar?

Hmm, interesting. guess I need to come up with something new for my batsuit lol

Batman just got owned.

well in batman 1 he wears a bulletproof vest....

over time increased exercise and training will increase bone density. batman has been training since he was 14 years old im pretty sure his skull can take a protective hit to the head and not fracture besides he runs around in a 200 pound suit leaping building and its the flaws in the suit that concerns you?

@Gammbitt: I am pretty sure extra exercise will not lead to extra bone density in the skull. And if you don't like my scientific breakdowns of stuff then don't bother reading it. Of course it is all science fiction, but if that were the case books like "The Physics of Superheroes" and "The Science of Star Trek" would not sell.

I agree that Sci Fi has to have the Sci or else it would just be Fi. Yes comics are Sci Fi. Every third character is a genius level scientist, even Joker.

lol, you made this on my birthday last year.