Aluminium Can

I would appreciate help from any person who has experienced and solved this problem.

Afraid I don't qualify..but a couple daft questions which may help.

a) Are you sure you have the most suitably alluminium alloy?

b) Do you nead to heat treat at some point during the forming?

Del

Thanks for the reply.I have checked these parameters and how they affect the forming of neck.But it appears the problem lies somewhere else.

<lies somewhere else.>

There is no Somewhere else. It lies -as rightly guessed by Del D'Cat-work hardening!

See for yourself by changing to another non-work-hardening or less-work-hardening Aluminium type.

3 forming operations??, 3 more to go??

I gotta go with Dell here. That metal is getting too hard to

flow the way you are asking it to go.

You need to anneal.

I know absolutely nothing about this sort of thing so please ignore me if I'm being stupid. Is it possible to do it the other way round?

Start by forming a 19 mm cylinder with bottom then expand (and shorten) the lower section.

I guess I'm really asking why this is a stupid idea!

Not at all Stupid.

This might solve all his problems.And the job will look like a blown Glass shape. Hydraulic pressurizing-- closed die set.

Al is possible to stretch 300%--SuperPlasticity is the name.

This is exactly how it is usually done, the neck is gripped and contained. The rest is expanded to required size. This is why on aly cans the necks or rims are thicker material as well, you could never get that by doing it the "wrong" way around.

Sorry but (t)his bubble is bust!

Isn't that the standard process to make 2 piece cans?

Probably very similar yes. You would need to somehow attach the lid to the rim after the stretching but then, why not stretch first and then clinch the rim?

Projects such as these start with the proper choice of aluminum alloy and forming process. You describe a necking down requirement that lends itself more to a CNC spinning operation using special tooling designed for the particular neck. I gather that you are expanding the shell (stretching) then trying to shrink the expanded material back down to form the neck. As you found out, a lot of work hardening is taking place that is resisting plastic deformation at this point. If you cannot change to a different alloy, you can try an annealing step as suggested in another post or possibly forming at an elevated temperature. As also suggested by another, hydraulic forming in a closed die is another good recommendation. If it were my project, I'd strongly consider hydraulic forming. One step and done.

Thank you all for applying your minds to my problem!I am using aluminium 1060(Soft).I cannot change that,but,I am inserting an annealing process between Draw and necking operations.Simultaneously I am trying the expansion technique,also.I hope to crack this problem.Thanks once again.

Nice to have a response (so many people just post a thread then evaporate!)

Let us know how it goes.

Good luck.

Del

Merry Christmas to all!