"cold welding" of aluminiumto die when blanking

[timfitz]

Hi all

I have a continuous problem of the aluminium sheet (0.4mm), that I am blanking, welding to the inside of the die. I have tried more and less clearance as well as reducing the die land to about 1mm, all to no avail. Is there any special tool steel that the aluminium wont stick to or a tough enough coating that will help? Both die and punch are well polished and because of further processing of the aluminium I cannot use any form of lubricant.

Thanks

Timfitz

 

[Goahead]

Are you blanking a stack of sheets? Would it help to interpose paper sheets? Could you try talc powder?

http://www.welding-advisers.com/

 

[timfitz]

Hi Goahead

Thanks for the ideas.

Paper sheets might work I will try today and let you know, talc will give us problems in production of the blanks (printing etc.). We are blanking up to 12 000 components per run and need to clean after every 200 to 300 units.

Thanks
Timfitz

 

[CoryPad]

There are hard coatings with low friction coefficient that might help. Diamond-Like Carbon, titanium nitride, and many others. I would start with DLC - look at this thread for suppliers:

thread281-170966

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[ajack1]

Timfitz, you state that the punch and die are highly polished, are they polished in blanking line? It does make a big difference.

You also state that no lubricant can be used, does that include a product that will evaporate? I have seen triethylene used where the part must be grease free.

 

[timfitz]

Hi all

Paper does not apper to make much of a difference and the operators find it very awkward to feed etc.

The polishing is a very valid point, the die and punch will both be polished in the oposite direction to the movement.

The evapotating lubricant might be an option. Production on this product has stopped at the moment so I will test when there is some time available on the press.

Thanks
TimFitz

 

[ajack1]

Timfitz, I think you will find you get better results polishing in blank line rather than opposite to it.