MadSci Network: Engineering
Query:

Re: Which ice hockey stick will shoot pucks better? Why did my stick warp?

Date: Sun Mar 21 19:25:00 1999
Posted By: Jim Stana, , Mechanical Design/Analysis Manager, Lockheed Martin Orlando
Area of science: Engineering
ID: 918702882.Eg
Message:

Warping is usually associated with things made out of wood, since the wood 
fibers can dry out unevenly, causing the fibers to stretch or shrink and 
change shape.  A composite stick might also warp if exposed to the sun.

I am a bit surprised that the aluminum stick warped.  Are you sure it is 
made entirely out of aluminum?

The only way aluminum would change shape like that is if you had left the 
stick with something heavy on top of it and the load caused it to bend.  

If the stick were machined out of a solid piece of aluminum, and not cast 
in a mold, then it is possible the stick would warp if it was not properly 
"stress-relieved" after the initial machining.  When you cut away a lot of 
metal from a solid block, what is left will have a tendancy to change shape 
unless you heat it up and relieve the residual stresses in the metal.  To 
prevent this from being a problem, you machine the part to a rough shape, 
say within a 1/16 of an inch of the final shape.  After the stress relief 
is done, the part (or stick in this case) is machined to the final shape.  
The stress relief process can cost money, so I can see a cheaper 
manufacturer skipping this step.

A casting or extrusion may also need to be stress relieved in this manner, 
or it could warp when machined as well.

From the cost, it is not obvious how your stick was made.  But if the 
manufacturer didn't take the time to stress relieve it, it could warp if it 
got hot.  Perhaps it got hot from the sun?

What really bothers me is the attitude of the store and manufacturer.  Did 
the aluminum stick warn of the possibility of warpage, and offer any advice 
on the use and care to prevent it?  If you bought it with a credit card or 
it is from a reputable manufacturer, I would definitly elevate my 
complaint, assuming you didn't violate any warnings or use and care 
instructions.  I can't imagine the stick getting hot enough to warp in the 
back of a truck in New England.

Can you supply more information as to the manufacturer and model number?  I 
live in Florida, but perhaps I can research it further.

Hope this incident doesn't make you lose your interest in Science.


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