The Complete Guide to Press Brakes
A press brake is an essential piece of equipment used in the bending of sheet metal into different shapes. It’s commonly found in machine shops and on factory floors and operated by metal fabricators. The machines are capable of forming simple and complex metal parts that are used in the automotive, aerospace and aeronautical, and marine sectors, as well as in the fabrication of metal containers, furniture, building and construction equipment, machine parts, electrical enclosures and dozens of other fields that require the use of formed metal.
The machines come in different varieties, that simplify work and add more precision and speed. They are often chosen by their bending capacity, or tonnage, as well as their overall dimensions in forming and bending differently-sized metal sheets. While there are variations as to the different types, a press brake consists of two main parts in forming the metal. This evolves around a clamping technique that secures the sheet metal in place and a punch positioned above the workpiece and a die below it. The clamping force acting between the main parts results in accurate curves, cuts, or bends. Machines can be operated manually, or where more precision and speed are called for, with CNC (computer numerical control) or NC (numerical control) in getting intricate shapes by entering parameters such as bend angles and depths.
Types of Press Brake Machines
The machines are generally defined by the source of the bending force. In this sense, there are mechanical, pneumatic. servo-electric and hydraulic press brakes. The first use an electric motor to power a flywheel and crank mech that stores kinetic energy to move the punch and bend the metal. Mechanical presses are some of the more widespread types due to their simple tech and are favoured for their relatively low purchase and maintenance costs as well as high-speed precision.
Pneumatic presses provide the clamping pressure by way of compressed air. They handle different types of metal fabrication equally well, and with high speed and clean operation, but fall short in clamping force when compared to the likes of hydraulic press brakes. These have superseded mechanical variants in just about every field owing to their extreme precision and control, very high tonnage, versatility with different fabrication methods, and very low costs.
A hydraulic press brake uses two hydraulic cylinders, allowing more control and consistent strokes. They can additionally be categorised by their movement in up-acting or down-acting, with each style having its own distinct advantages. Lastly. servo press brakes or more often called CNC brakes supply the pressing force via two synchronized servomotors used to power a belt and pulley mechanism. This lends them unparalleled precision, control, efficiency, and ease of use.
Metal Bending Methods
A press brake can be in two basic modes of metal bending – namely, air and bottom bending. Air bending involves three points of contact between the punch, sheet metal, and die, two with the die and one with the tip of the punch. The workpiece is pushed only part way down into the die, usually at an 85-degree angle to get the desired shape. This method is often used for thicker metal sheets (10 gauges or higher). Higher precision is achieved with a CNC machine.
Bottom bending encompasses a technique where the metal is pressed fully into the bottom of the die. This allows for more accuracy in the bend angle, as it depends solely on the tooling, or the choice of punch and die, used.
Advantages of Using a Press Brake
Compared to other machines and methods used in metal fabrication and processing, a press brake has several advantages. The first is that there’s less waste, as the machine is accurate and precise in getting the desired shape. The newer tech incorporated into every press brake machine also implies easier operation, meaning less operator training, lower labour costs, and increased worker safety. Moreover, quick production times coupled with precision owing to CNC control, improve output and reduce downtime.
Additionally, a press brake is very versatile in getting a range of different shapes in the metal, and automated forming of workpieces in different thicknesses. The machine can be used with different dies to get complex shapes, often aided by programmable variants. Lastly, the cost of press brakes isn’t prohibitive as it once was, and they’re becoming a standard feature in more businesses involved with metal fabrication.
Choosing a Press Brake – What to Look For
The machines are chosen usually based on the metals they’ll be used on. This takes into account things like tensile strength, the thickness and size of the metal, and the force or tonnage need to form it. Besides choosing the right type of machine in terms of operation, factors like tonnage, or the clamping force the machine can exert also play a part. Choose a machine with high tonnage when working thick and hard metals, or brakes with low tonnage when you require more precision bends in thinner pieces. Along with the range of safety and function features (programming and tooling choice) that make work easier and faster, also consider the length of the machine and its ability to work differently sized metal sheets.