Sheet metal bending is a fundamental fabrication process that transforms flat sheet metals into intricate and functional workpieces. The process creates essential items used across diverse industries, ranging from automotive and aerospace components to everyday electronics and household appliances and building materials.
Fundamental to shaping sheet metals with precision, power, and control are press brakes. These metal fabrication machines transform metal sheets into the desired angles and shapes using force and varied dies and punches.
Punches apply force to sheets or thicker metal plates, while dies provide support and shape metals as they are bent. The high bending force, consistency, repeatability, and tooling versatility make these machines an essential component in any metal fabrication business.
The Anatomy of Press Brakes
To understand how press brakes work, let’s familiarise ourselves with the basic parts:
- Frame – The main structure that supports the entire machine, consisting of a welded and reinforced structure.
- Bed – The flat surface that supports the die and the workpiece during bending.
- Ram – The moving component that moves the punch and forces the sheet metal into the die.
- Punch – The upper tooling attached to the ram, and forms the upper part of the bend.
- Die – The lower tooling component that works with the punch when shaping the workpiece.
- Backgauge – A device that positions the metal accurately for each bend.
The working principle of press brakes is relatively simple. To shape sheet metal or plates into the desired shape, the workpiece is placed on the bed and aligned using the backgauge. This ensures precise bending.
Next, punches and dies are used to achieve a variety of shapes, angles and bends. These need to be in the right size and shape. They can range from straight, gooseneck, and offset punches to V-shaped, U and Z-dies and specialised dies (for radius bends, hem bends and box forming).
The workpiece is then clamped between the punch and die. The ram exerts the necessary force to deform the workpiece and bend it according to the die profile. After bending, the ram retracts, and the finished piece can be removed.
Common Press Brake Types
Press brakes are commonly categorised by the power source that exerts force onto the workpiece. More common are hydraulic press brakes, with servo-electric or CNC and pneumatic types dealing with differing tasks and different materials. While basic, mechanical press brakes are also seen in smaller operations. Let’s take a closer look at each type.
Hydraulic Press Brakes
The hydraulic pressbrakes are the mainstay of larger operations. Equipped with the tonnage or force to bend thicker sheets and plates, hydraulic press brakes use durable and exceptionally reliable hydraulic systems consisting of motors, oil pumps, valves and cylinders.
The hydraulic press brake machine moves the ram vertically, uses oil to exert consistent force and has precision control systems to regulate pressure and ensure bending control. Hydraulic press brakes for sale like the Absolute Hydraulic Pressbrake. 3200mm x 135Ton. 2 Axis NC Estun E21 Control are preferred for their precise bending, high tonnage, the ability to handle thick materials, and the versatility to achieve multiple bend types and workpieces in varied and intricate shapes.
Servo-electric (CNC) Press Brakes
(CNC) Press Brakes are programmable versions equipped with Computer Numerical Control (CNC) systems for higher accuracy, improved operational safety and lower maintenance. They include an automated feeding system to accurately control the workpiece and tooling positioning.
Servo motors control the movement of the ram using a ball screw, ensuring consistent force and faster results. The improved precision and versatility come at a price, though.
For repetitive or simple shapes and angles, consider investing in a programmable NC hydraulic press brake, like the high-tonnage ABSOLUTE. Hydraulic Pressbrake. 4000mm x 210Ton. 2 Axis NC Estun E21 Controller, or when working with thinner and smaller sheets, the affordable yet competent Absolute Hydraulic Pressbrake. 3200mm x 90Ton. 2 Axis NC Estun E21+ Controller.
Pneumatic Press Brakes
Using compressed air as a power source, pneumatic press brakes benefit from smaller footprints, lower weight and faster setup times, making them ideal for light to medium tasks involving thinner metal sheets.
Key Uses and Industries
- Automotive and aerospace industry – Bend sheet metals into fuselages, body panels, brackets, exhaust system parts, wing parts, engine covers and more. Press brakes ensure precision, tight tolerances, and parts meeting the requirements set out in strict regulations regarding strength, quality and safety.
- Electronics and home appliances – Machines shape sheeting into fridge panels, HVAC ducting and components, appliance housings, as well as electrical enclosures, cabinets and connectors.
- Furniture – press brakes craft intricate and sturdy metal parts for office and home furniture.
- Construction – Structural elements, roofing, cladding, rain gutters and other architectural elements are all shaped and formed using press brakes.
- Medical equipment – Precision surgical instruments, diagnostic tools and hospital furniture are just a few uses of press brakes in the medical and health industries.
Buying Considerations
- Tonnage – The force in tons determines the metals and the metal thickness that press brakes can work with without sacrificing precision or incurring damage. Consider factors like metal tensile strength, ductility, density and thickness. Steel, for instance, requires more tonnage than aluminium sheets.
- Bend length and depth – Consider the maximum length and depth of bends you need to perform. Factor in bed sizes, usually ranging from 1.2 to 4.3m, and ram stroke, or the distance the ram can travel when bending the sheet to the desired depth.
- Production volumes – Assess your production requirements. For high-volume production, an NC or CNC press brake may be more suitable due to higher speed and automation, with lower operator input required.
- Safety features – Emergency stop buttons, light controls, presence sensing devices, pressure relief valves, laser guarding system, auto-off functionality and two-hand controls are just a few features that ensure the operator’s safety.
- Precision Requirements – For applications that demand high precision, a CNC press brake is the best choice due to its advanced control systems.
- Budget – Factor in initial purchase costs, the price of specialised tooling, and for high-maintenance machines like hydraulic press brakes, operational and maintenance costs.
Apart from small mechanical and pneumatic press brakes, hydraulic, NC and CNC press brakes are an investment, but one that rewards businesses with precision, high production volumes, efficiency and the versatility to work with varied metals, angles, shapes and bends that grow your business.