A factory was making door trim panels but the metal was cracking when pressed. How did the company prevent the cracking? Mysteries of Science
Transcript
A large metal working factory was making interior door trim panels for the new Lincoln. The perimeter of the panel needed to have a raised bead of metal formed by pressing the sheet in a hydraulic press with a pattern set of embossing plates.
However forming the raised up bead stretched the metal too much causing cracking. Using a softer grade aluminum worked, but now the product was too easily dented.
Different levels of annealing were tried. But when the bead formed well the aluminum was too soft.
One solution offered was too anneal the metal where you are going to form the bead and leave the rest of it at hard temper.
But there was no such thing as selectively annealed aluminum.
How did the company find a balance to prevent cracking while maintaining an aluminum that can hold up to dents?
Here's the rest of the story.
An engineer marked a portion of an aluminum sheet generously with a black marker. Then he ran the sheet through a radiant heater. The black area absorbed heat and annealed the aluminum while the shiny areas reflected the heat energy and didn't get hot enough to change the structure.
