how much does aluminum expand in hot weather ?

[Richard Miller]

hi, I'm sure this has been asked before but I couldn't find it using the search function.

I'm just about to put the edge molding on the sides of my trailer and I'm wondering if I need to cut to allow for expansion during the heat of the summer.
Right now the garage temps are running abt. 70º and I plan on just floating the aluminum on the sides and capturing the edge with the molding and the door edge molding, If I cut the aluminum to match the profile of the trailer will the expansion in the summer heat cause the aluminum to expand excessively and oil can/get all wavy ?

Thanks, Richard

[eamarquardt]

Linear Temperature Expansion Coefficient
(10-6 m/m K) (10-6 in/in oF)
Aluminum 22.2 12.3

or 50" will expand about .030 with a 50F increase in temperature.

Cheers, Gus

[Kody]

The Coefficient of thermal expansion for aluminum is .000023 per degree Celsius, a 1 meter bar will grow 2.3 mm if its temperature increases 100 degrees C.
This info is taken from this web site here :- http://wiki.answers.com/Q/What_is_the_C ... r_aluminum.

The expansion is proportional so maybe you could work from the minimum temperature for where you live as your base line and call this your "zero" or starting point. The final temperature can very well be a rise of 120 deg C. It depends if the aluminium is in the sun and, or if there is a breeze cooling it down.
Measure the length of the aluminium part then multiply the length by 0.000023 and by the rise in temperature above your base point. This should give you the final increase in length for the temperature rise of the aluminium.

Check out this table also for more info. http://hyperphysics.phy-astr.gsu.edu/hb ... thexp.html

Hope this helps

Kody

[halfdome, Danny]

I make a 15 degree butt joint around the flat area of my roof so I don't have to fight a 16' piece of aluminum trim in a 8' tall building.
I haven't noticed any expansion or contraction especially since it has stainless screws wherever the manufacturer placed holes for fastening.
If your teardrop was going to be rocketed into space there might be some concern, but down here on earth I think you'll be fine.
Danny

[aggie79]

Richard,

I cut my aluminum about 1/4" shy of the full dimension (profile and roof aluminum). I used washer head SS screws and drilled the screw holes in the aluminum oversize.

All of this was a lot of extra work that I don't think was necessary. With our 20 degree winters and 110 degree summers I do get some oil-canning but it is very minimal. I think the reason for this is not because of how I installed the aluminum but because it doesn't really expand that much.

Take care,
Tom

[Martiangod]

I like Aggies suggestion of leaving 1/4 inch. I built outside in winter and went flush, come spring and warm sun expansion and oil canning was quite prominent, Gage made suggestion to trim, so I pulled trim, trimmed about quarter inch, drilled alum and reinstalled trim, quite easy compared to hanging, it helped alot on the oil canning, still get some but its livable what I get now

[Richard Miller]

Hi Guys, thanks for all the responses.

I think that I'll go with the advice Tom has on allowing additional clearance on screw holes like those used for the side marker lamps etc.
and I'll allow 1/8th in. clearance around the edges. With the skin mounted tightly at the door edge molding this should allow plenty of room to expand outward according to the figures that Gus and Kody provided.
Thanks, Richard