After the annealing operation, the temperature of the aluminum circles’ surfaces is really high. And some of the plants aren’t patient enough to wait for all of them to thoroughly cool down, they however tend to be very rush to carry the aluminum circles and to package them without even further engaging in the safety inspection. Especially as they do so, it will provide sufficient ground for the edge warping issue to pop up.
Premium supplier will rigorously conduct the safety inspection procedure to their products. For instance, they can double-check all the external dimensions, physical property and chemical components to secure the grain size of the aluminum disc. They will not start to package them until they make sure everything is right.