I am new to muscle wire and getting a little confused about all the lingo out there and was hoping someone could clear some stuff up for me?
I'll try to clear this up for you - note, I'll be doing research as I go - I'm not an expert in this...
I've heard of muscle wire that contracts in length (about 2-5%) when current (generating heat) is applied to it.
Yes - this is a form of SMA - Shape Memory Alloy:
Note that it is one form - depending on how the metal is originally manufactured will determine how it deforms and reforms.
I've also heard of muscle wire being trained to remember a particular shape and when heated, reverts back to that shape.
Yes - as originally manufactured; as far as I know, you can't change it (well, not easily for the homebrewer, I'd imagine) after it is manufactured.
I've heard of Flexinol, Nitinol and SMAs.
So my question is...which is which?
Flexinol is a trade name for a type of SMA manufactured by this company: http://www.dynalloy.com/
Nitinol is another trade name for a different type of SMA - and derives its name from its composition and where it was discovered in 1962 by Frederick Wang: Nickel Titanium Naval Ordnance Laboratory:
SMA (Shape Memory Alloy) is the generic term for such alloys (of which there are several).
Whats the name of the product that contracts, and which is the one that remembers its shape? or do they all do the same thing?
That is the same thing. At the time of manufacture, SMAs are shaped into their "cool" form. Some also have a high-temperature form (so-called "two way" SMAs). The SMA wire is thus formed in one manner, then when heated, lengthens - when cooled, it contracts back to its original shape.
And whats the difference between Flexinol and Nitinol? or is this a Kleenex vs tissue thing?
Both are essentially trade-names, as mentioned above, but Nitinol, being a product of the US government, and the one kind of SMA a lot of people are familiar with due to its being mentioned frequently in media, has acquired a common-name status, closer to "Kleenex", to use your analogy - though technically, the proper common-name of such metals are SMAs (Shape Memory Alloys).
I read the literature on the Dynalloy site and I am still confused.
That confusion might be unintentional, or intentional - remember, they are trying to sell you a product - their product - an SMA that is likely a different alloy composition than others (whether it is better or worse than others, I don't know). It does seem like a complex subject, though.
If anyone has used any of these products and could clear this up for me I would really appreciate Smiley
Well, I hope the above helps (and doesn't make things worse!), as I have never played with such metals...
Also, any other advice on muscle wire would be greatly appreciated. For example, should I use High Temperature or Low Temperature?
Well - I guess that would depend on what "High Temperature" and "Low Temperature" means in the world of SMA metals. Since you're asking this in an electronics forum, it means you are likely to want a metal that can react to temperature changes caused by current flowing through it, heating it up (resistance). Whether you want high or low temperature, probably relates to the ambient temperature you'll be using it at, plus the design of your device that will be actuated, whether there will be stress on the SMA as it is heated and cooled, etc.
Finally - a couple of other options to keep in mind (or to ponder on):
I hope this helps to clear up some of your confusion...