i need info on strong materials *weight Vs. cost. please help this is getting ridiculous!!! 
angle aluminum works the best for us. easy to use. light. strong. cheap. readily available. homedepot always has alotâŚ
Carbon Fiber?
Titanium?
Perhaps if you could give us some more information on what you want these materials to do we could be more helpful.
What are you trying to make? How strong? Whats your budget? What are your manufacturing capabilities? How much time do you have?
Those would be some nice starting points.
-Andy A.
Aluminum is the tried and true material for most FIRST robots. Remember though, until this past year, so called âexotic materialsâ were band. For robot frame construction, aluminum is still the way to go. Its readily available at any metal supply store, and relatively cheap.
Titanium and carbon fiber can be quite useful for teams that can afford it, and have to tools to shape it. I doubt any team would ever use titanium for their frame, seeing as it needs to be welded in an argon atmosphere. Titanium shafts are a good replacement for steel shafts, seeing as it is quite a bit lighter, by volume. (roughly half that of steel) Titanium is quite a bit harder to machine.
Carbon fiber is a whole different story. It can be quite useful for grippers and manipulators. We(1114) used it last year for our big ball gripper. It was an incredibly lightweight solution to designing our ball gripper. Carbon fiber has a density roughly half that of aluminum. It is also dangerous if the vapors are inhaled when machining, so teams should take precautions when working with it.(filter masks, work outside, and of course safety glasses)
Both titanium and carbon fiber are available at
http://www.robotmarketplace.com/
although Iâm sure there are cheaper suppliers for the stuff
mcmaster-carr also has titanium, in the raw materials section under metals
Both are hellish to machine. (Titanium eats tools, carbon fibre emits very nasty splintersâand if youâre making your own, keep the resin out of your lungs.)
Edit: Heck; Tyler beat me to it. And the welding thing is a good pointâin addition to argon, you need very special welding rod; it makes you wonder how the Russians ever managed to put together the Sierra class of titanium-hulled submarines (useless factâŚ).
Letâs not forget about wood, either. My team has never used it, but take Rage Team 173 for example, they had their little red box (with an awesome ball manipulator) go all the way to the Championship finals (or maybe they won it). All I can say is that you shouldnât necessarily weigh that option out either. We all know itâs easy to machine, and it can be pretty light, compared to steel. Aluminum is probably lighter, but I am pretty sure Wood is cheap. I just think carbon fiber and titanium are out of alot of teamâs budgets⌠It was on my team.
lets not forget Lexan too. im sure most teams have used or uses plenty.
Yes we love our wooden robots, they are awesome, and the year was 02â and yes with the help of 71 Beatty, and 66 The Flyers, we won that year. It was my freshman year, and the last year at Disney, it was awesome, but plywood isnt always a good choice, we use a cabinetry grade plywood(I forget what kind wood it is though.), that is meant to deal with a lot of abuse, but it can get heavy depending on how much is used. The best part is, that if it breaks you can just wood glue it back together, there is a picture her on CD in the 2003 gallery from UTC New England of that little incident. But again extremely easy to machine. It all depends on what you are looking for.
The best material is not neccesarily the one with the best strength to weight ratio as people have pointed out. Aluminum is not actually significantly stronger (per weight) than steel (in fact, its significantly weaker than the strongest steels), the reason that it is so popular is that it is easier to create more efficient designs out of aluminum because of its low density and ease of machining. In certain cases, this may even be true for wood.
Which weighs the same as aluminum.
Also Ti is half the strength of steel at half the weight. As for the welding comment yes you have to properly back gas it but you should be with all you welding already. Granted a Ti fire is is one of the scariest things that can happen in a machine shop.
To use carbon fiber and cure it properly you need to either autoclave or vaccum bag a prepreg, facilities most people donât have access to. And it is important to understand the influence of directional orientation of fibers. For instance in carbon fiber bicycle design you trade off which directions you want to flex in for compliance to road but also where you need rigidity to minimize drivetrain losses due to flex. The advantage to CF is deciding where you want the strength.
Some light strong polymers include Polyetheretherketone, or PEEK. Which is a plastic with a low creep value. Cost is on the order of $30 a lb last I checked. PEI, polyetherimide(?), which has the trade name Ultem is another strong plastic.
The real questions you should ask are:
What property is most important to me?
Tensile strenght, compressive strength, flexural strenght, impact strenght?
Are thermal effects on properties important?
Is corrosion an issue?
There are many more but the material choice is application dependent.
Sorry for the rambling
Pete