Bending machines are used to bend metal plates either manually or automatically. There are two main types: 1) press bending machines, which form bends by clamping materials between a punch and die; and 2) rolling bending machines, which use three rollers to form bars into circular arcs. Bending machines provide efficiency for workers and allow for metal recycling, but safety precautions must be taken since sharp plates can cause injuries if not handled carefully. They also require space and significant financial investment.