Reinforcing bars are inserted into the cement to provide stability.
Broadly speaking, there are three types of rebar benders: manual, hydraulic, and electromechanical. The simplest machines, manual hickey bars, are readily available and inexpensive. Hydraulic machines are slower and less durable than electromechanical devices, but they are also cheaper. Manufacturers of large rebar bending machines build them to customer specifications, making each machine a little different. These giants are almost always electromechanical.
Concrete is often poured over a rebar grid to increase its strength and durability.
The task at hand determines the nature of the rebar bending machine. For occasional use on smaller diameter rebar, a hickey bar is often the best choice due to its low cost. A hickey bar is a simple lever arm, a long steel bar, with a slot or pins to hold the rebar at one end. Arm strength and body weight are used to apply force to the other end of the hickey bar to bend the rebar.
For a tight turn, two hickey bars can be used. These single rebar bending machines can be used on rebar up to 5/8 in. (1.6cm) in diameter. Hickey bars with cutting capabilities are also available.
For bending more than a few pieces of rebar, an electromechanical or hydraulic machine is a better option. Some of the hydraulic machines are quite portable, weighing only 33 pounds (15 kg) and designed to be portable. These machines are designed to bend rebar that is exposed after concrete is poured over a rebar web. With these machines you can make turns of up to 180 degrees.
When the contractor is bending rebar in preparation for installation in a mold, larger machines are usually chosen. Larger benders are usually transported on trucks and typically do not leave the truck bed until the rebar is in place and the machine is returned to storage. These machines run on diesel fuel, allowing them to run on jobsites that don’t have electricity.
Even large on-site machines can handle rebar up to 30 mm (1.18 in.) in diameter; larger diameters should be bent out of place. The most powerful multi-purpose programmable rebar bending machines are large, stationary and expensive. They are typically screwed into concrete floors in industrial buildings, where they are bent and sheared. External rebar benders generally work like pipe benders, but even these can only create 180-degree bends.