Persoz apparatus for cupping tests

It shows clearly that the very slight increase in the Breaking Load due to the cold work is only obtained at the expense of the Depth of Impression at rupture. 

The absolute minimum cold work should be specified for sheet aluminium required for pressing or other work of a similar nature. The amount of cupping, which annealed sheet will stand, is clearly superior to that which sheet, worked even very little, can support. 

It shows that an increase of thickness must be resorted to, if an increased cupping value is desired. 

Conclusion. Whatever the thickness, all sheet destined for pressing should be annealed, and this condition should be included in specifications. 

Variation of Depth of Impression and Breaking Load toith increasing annealing temperature, after varying amounts of Cold Work. 

---