A bend test is used to determine whether a specific piece of metal in question will break or fracture under pressure. This is important in the construction of any project using metal, otherwise the building or the item being made could collapse from the immense pressure exerted on it. Every piece of metal made cannot be tested, therefore certain pieces are tested and if they pass, the other pieces are made using the same process. The results of a bend test are reported differently depending on the type of material tested. There is no standard method for reporting the durability that applies to all materials, rather each group has its own set by which it is judged and compared to other metals in that group.
The bend test is essentially measuring a metal's ductility. Ductility defines how easily a metal can bend without breaking. The higher the ductility of a metal, the more it can bend without breaking or becoming deformed from its original shape. This is important because certain metals must handle pressure without snapping yet still be ductile enough to bend slightly and not lose their support or shape. Copper and steel are two metals that have a high ductility and do well under pressure.
To perform a bend test, a specific sheet or strip of metal is bent by a predetermined amount, often into an arc shape. After the bend is made, the metal is carefully examined to see if any breaks or cracking occurred in the piece, and the testers note whether the metal broke along or against the grain. The grain is a term used to describe the direction that lines in the metal appear to run when examined closely. The metal is also checked to see if one side fractured while the other side did not. Results for the test are determined by how the metal held up during the bend test, and how much it may have fractured or broken.
Bend test machines are used by companies and are responsible for performing the bend test on various pieces of metal. The piece being tested is inserted into the machine which then bends the center into a curve or arch specified by the operator. When the process is finished the machine releases the piece and the metal can be removed and examined to determine the results. These machines are available for companies to purchase from manufactures and suppliers.