The CNC press brake is a kind of press brake controlled by a computer numerical control (CNC) system. CNC press brake can fold sheet metals into various profiles. The bending accuracy and quantity are related to the synchronous system, the hydraulic system and the back gauge.

The function of these components is affected by the number of CNC press brake axis. Understanding these axes is crucial for selecting, configuring, and operating a CNC press brake effectively. This article will introduce the function and working principle of the press brake axes.

I. What Are the Axes on the Press Brake？

The CNC system controls the movement of the press brake axes. The press brake axes are named based on their position in the space coordinates. The press brake axis refers to the mechanical elements which control the different parts’ movement of the press brake.

These movements may include up and down movement, back and forth movement, left and right movement, even including the fine adjustment of metal sheet’s bending angle. The precise movement of axis ensures the accurate position and angle of metal in press brake, facilitating the precise bending operation.

The precision required for the workpiece determines the number of axes needed by the press brake. Typically, a CNC press brake has at least three groups of control axes: Y1/Y2, X, and R axes. These are used to control the movement of the back gauge, ram, and other parts.

A torsion shaft press brake can be used to bend simple workpieces with at least two axes, which are used to control the Y-axis of the ram and the X-axis of the back gauge. The simplest press brake only needs a Y-axis to control the up-and-down movement of the ram.

The accuracy and repeatability of the Y-axis motion determine the accuracy of the bending angle. The control system uses axes to control the movement of different parts, thereby controlling the bending angle and size.

II. What Is Back Gauge on the Press Brake?

The back gauge of the press brake is a component, which helps metal sheet positioning and aligning before its bending. It is located on the rear of the bending tool and moves along the X axis.

The back gauge is composed of a series of stop fingers and blocks, which can be adjusted to desired location based on required bending length. These fingers can be operated by manual, electric or CNC system.

Back gauge aims to ensure the metal sheet’s consistence and exact position when bending. It realizes the precise bending angle, length and geometric shape via controlling the depth and position between the metal sheet and the bending tool.

It plays a paramount role in improving productivity efficiency, decreasing the equipment setting time and ensuring the repeatability of bending operations. It eliminates the requirement for manual measuring and suspecting, thus realizing the consistent and efficient bending process.

In modern press brake system, the back gauge can be integrated with the press brake controller to fulfill automatic positioning and controlling. This integration offers seamless cooperation between the back gauge and the press brake axis, facilitating accurate bending operation and precise and repeatable bending.

The back gauge is controlled by the CNC control system to accurately position the sheet metal. Typically, a back gauge will have at least one axis, and more advanced systems can have up to six axes. A separate motor drives each axis to slide back and forth in a specific direction.

Ball screw, synchronous belt and axes realize synchronous movement together. These precise repetitive actions ensure the accuracy of each batch of workpieces. Optical sensors and CNC programming on the press brake can also be used for positioning.

For a detailed guide on this topic, you can watch this video on How to Correct the Errors of an Electro Hydraulic Press BrakeDelem DA 66S&DA69 S.

The back gauge of press brake is closely related to the press brake axis, and mutually ensuring the accurate and precise bending operation. The press brake axis refers to different moving axis inside the press brake, such as X axis, Y axis, Z axis and R axis.

These axes control the positioning of bending tool and movement of metal sheet during bending process. On the other hand, the position and height of back gauge can be controlled by adjusting the press brake axis. Through controlling the position of Y axis and X axis, the back gauge can be aligned with piecework, thus the accuracy and consistence of bending can be ensured.

Nowadays, the back gauge and press brake are usually integrated and controlled by CNC system. This integration allows for automatic positioning and precise controlling between press brake axis and back gauge, achieving an efficient and exact bending process.

III. Main Groups of Controlled Axis

1. Y-axis: Vertical Ram Movement

The Y1/Y2 axes are the beating heart of modern electro-hydraulic servo CNC press brakes, governing the vertical motion of the ram (upper die). The depth of your understanding of this system directly determines your factory’s product quality rate and consistency.

(1) Key Differentiator: How Independent Dual-Cylinder Synchronization Eliminates Angle Deviation and Deflection

A common misconception in the industry is confusing the idea of a “synchronized press brake.” Older torque-shaft-synchronized machines use a rigid torsion bar to mechanically link both hydraulic cylinders in an attempt to enforce synchronization. However, this approach carries fatal limitations:

• Inability to compensate for deflection: When the machine is under load, the frame and ram inevitably experience micron-level elastic deformation (deflection), and the torsion shaft itself twists. As a result, the ram’s center and ends move unevenly—leading to bends that are deeper in the middle and shallower at the ends, ultimately scrapping long workpieces.
• Poor handling of off-center loads: When the workpiece is not centered or asymmetric dies are used, the torque shaft system cannot balance the force distribution between sides, causing the ram to tilt and severely damaging both precision and machine lifespan.

In contrast, independent Y1/Y2 axis control is true “electro-hydraulic servo synchronization.” It fundamentally solves these issues by equipping each side of the machine’s uprights with its own hydraulic cylinder and high-precision linear encoder.

Insider insight: The essence of independent Y1/Y2 control lies in the evolution from “passive mechanical synchronization” to “active real-time adjustment.” Instead of opposing physical deformation, the system continuously monitors it and uses high-frequency servo valve signals to dynamically and independently modulate the flow and pressure on both cylinders. The result: the ram edge remains perfectly parallel to the worktable under any load—eliminating angle deviation and overcoming deflection at its root.

(2) Visual Breakdown: How Servo-Hydraulic and Electric Servo Closed Loops Achieve Micron-Level Precision

Imagine an endlessly vigilant correction loop that reacts with lightning speed—that’s the daily operation of the Y1/Y2 closed-loop control system:

1）Command issued:

The CNC controller sends target position commands (e.g., descend to 80.00 mm) to the servo valves on both sides.

2）Action executed:

High-performance servo valves (such as those from Rexroth or Bosch) receive minute electrical signals and instantly, precisely direct hydraulic oil into the Y1 and Y2 cylinders, driving the ram downward.

3）Real-time measurement:

Linear encoders mounted on the C-frame plates measure the absolute position of both sides of the ram at microsecond intervals and feed this data back to the CNC controller. The C-frame design smartly isolates measurement from the structural deformation of the columns, ensuring an unwavering reference base.

4）Comparison and correction:

The controller compares the actual readings (e.g., Y1 = 79.98 mm, Y2 = 80.01 mm) against the target position.

5）Instant adjustment:

On detecting any deviation, the CNC sends correction commands to the servo valves, fine-tuning oil flow into both cylinders until the difference between target and actual positions is less than a minute threshold—typically within ±0.01 mm.

This full “command–actuation–measurement–correction” loop occurs hundreds of times per second, achieving micron-level repeat positioning accuracy—the physical foundation of consistently precise bending angles.

(3) The Art of Off-Center Control: Strategies for Precise Bending of Asymmetric Workpieces

The true artistry of independent Y1/Y2 axis control lies in its ability to handle off-center bending, opening the door to high-value, complex manufacturing.

1）Conical bending:

When producing tapered parts—wider on one end, narrower on the other—simply program different target depths for the Y1 and Y2 axes in the CNC. The system automatically controls both cylinders at distinct stroke lengths, completing the bend in one pass with perfect taper accuracy—something impossible on torque-shaft machines.

2）Multi-die operations:

Multiple dies of varying heights can be mounted on the ram simultaneously for different bending tasks. The Y1/Y2 system keeps the ram’s posture balanced so that, even under unequal loading, each bend maintains its precision.

This capability empowers factories to tackle custom, complex orders—yielding profit margins far beyond those of standard part production.

IV. Axes on the Back Gauge

The back gauge determines the bending accuracy of the workpiece.The more complex the workpiece is, the more axes are required for the back gauge. There will be at most 6 axes on the back gauge, and these axes will have different variants. Each axis has a separate drive motor to ensure positioning accuracy.

1. X-axis: Horizontal Backgauge Movement

The X-axis controls the forward and backward movement of the backgauge, directly determining the flange length in bending operations. Its speed and precision profoundly affect the factory’s production rhythm and the final product’s dimensional accuracy.

(1) Coordination of Speed and Precision: How Ball Screw Technology Shapes Production Cycles

Modern high-performance press brakes typically use a servo motor + ball screw drive for the X-axis. Compared to conventional trapezoidal screws or belt drives, the advantages are overwhelming:

• High-speed positioning: Ball screws generate rolling, not sliding, friction, allowing the backgauge to move between positions at extremely high speeds—up to 500 mm/s or more—greatly reducing waiting time between bending steps.
• High precision retention: The minimal transmission backlash of ball screws, paired with the servo motor’s precise control, ensures exceptional positioning and repeatability accuracy (as tight as ±0.02 mm).

Expert insight:

X-axis speed isn’t just about being fast—it defines your production rhythm. On a part requiring six bends, saving just one second per X-axis movement compared to older machines means saving six seconds per part.

For an order of 1,000 parts, that’s a pure machine time reduction of 1.6 hours. Multiply that by your shop’s hourly operating cost, and you have the direct profit generated by ball screw technology.

(2) Controlling Cumulative Error: The Key to High-Precision Multi-Step Bending

For complex parts requiring multiple continuous bends, the X-axis’s repeat positioning accuracy is the critical lifeline. Suppose a part has ten bends and the X-axis deviates ±0.1 mm each time—the cumulative error could become significant. Although CNC systems position based on absolute coordinates, minute backlash and response errors still exist. A high-precision X-axis system ensures every move is virtually identical to the programmed position, minimizing accumulated error and maintaining dimensional consistency from the first bend to the last—preventing the nightmare of discovering scrap only at the end.

• X1: left stop finger back and forth moving axis
• X2: right stop finger back and forth moving axis

2. R-axis: Vertical Backgauge Finger Movement

The R-axis controls the vertical movement of the backgauge fingers. It’s the “key” that transforms bending from a two-dimensional operation into a three-dimensional process capable of complex forms.

(1) Application Scenarios: Achieving One-Step Forming for Z-Bends and Hemming Operations

• Z-bends / Step bends: The classic use case for the R-axis. After the first bend, the material’s edge lifts upward. During the reverse bend, the R-axis automatically raises the backgauge fingers to leave enough clearance for the upturned flange to slide beneath, ensuring precise positioning for the second bend.
• Locating irregular parts: When working with parts that have protrusions or unusual shapes, the R-axis flexibly adjusts its height to avoid interference and establish a stable positioning reference.
• Hemming process: During a hemming operation—where a sharp bend is made first, followed by flattening—the process involves two tooling setups at different heights. The R-axis automatically matches the backgauge height to suit each stage.

With an R-axis, these complex processes can be completed in a single setup, eliminating re-clamping errors and wasted time.

(2) Efficiency Comparison: Time Cost of R-Axis Automation vs. Manual Adjustment

On machines without an R-axis, operators facing such tasks must:

1）Adjust manually: Loosen screws and move the entire backgauge beam vertically by hand—a time-consuming, imprecise process.

2）Change gauge fingers: Replace them with elongated or specially shaped ones—requiring a stop in production.

3）Abandon precise gauging: Rely on visual alignment or marked guidance for the next bend—resulting in poor consistency.

With CNC-controlled R-axis automation, all these adjustments happen instantly through programmed control. For a typical Z-bend, R-axis elevation may take just 2 seconds, whereas manual adjustment could consume 1–2 minutes. In jobs requiring frequent changes, the efficiency boost is exponential, freeing operators from repetitive low-value tasks and letting them focus on true production.

• R1: left stop finger up and down moving axis
• R2: right stop finger up and down moving axis

3. Z-axis: Lateral Backgauge Movement

If the R-axis unlocks height, then independent Z1/Z2 axes liberate width. They control the left and right backgauge fingers moving independently along the machine’s horizontal beam.

(1) Programming Logic: Using Z-Axes to Complete Multiple Bends in a Single Setup

Imagine fabricating a U-shaped sheet metal part. On a machine without Z-axes, you would:

Bend both long sides.

Then manually reposition both gauge fingers to the center to locate and bend the short middle edge.

This manual interruption severely disrupts production flow. With Z1/Z2 axes, the operator simply places the sheet once, and the program executes automatically:

• Z1 and Z2 move outward to locate and complete both long-side bends.
• Then they automatically shift inward to the preset narrow position. The operator only slightly repositions the sheet to perform the middle bend.

All these operations occur seamlessly in a single setup and program—dramatically multiplying efficiency.

(2) Intelligent Avoidance and Support: Automated Solutions for Irregular and Tapered Workpieces

The true power of Z1/Z2 axes shines when processing nonstandard workpieces:

• Irregular sheet support: For sheets with uneven edges, Z1 and Z2 can be programmed to position optimally for stable support, instead of sticking to symmetrical placements.
• Tapered workpiece automation: When bending tapered or angled parts, Z1/Z2 automatically adjust to match the part’s slanted edges, offering accurate two-point positioning—especially effective when combined with independent X1/X2 axes.
• Smart avoidance: For sheets with holes, Z-axes can reposition the fingers to avoid the holes and use solid areas for gauging—achieving precision and speed impossible with manual adjustment.

In summary, the Z1/Z2 axes transform the backgauge from a simple barrier into an intelligent, flexible “mechanical hand,” vastly expanding the press brake’s automation and process capabilities.

Now that we’ve thoroughly explored the four core axes, it’s clear that every technological advancement serves a single purpose: to produce higher-quality, higher-value parts in less time and at lower cost. That is the fundamental logic behind how axis systems generate profit.

V. Other Axes on the Press Brake

1. V Axis (Deflection Compensation)

When bending a long, thick steel plate, even with high-end Y1/Y2 axes, a certain physical phenomenon is unavoidable. Under immense tonnage, the machine’s ram (upper beam) and table (lower beam) experience slight elastic deformation—concave in the middle and raised at both ends, much like a bent wooden stick. This deformation transfers to the workpiece, causing larger angles in the center and smaller ones at both ends, creating a banana-shaped result. This is what industry professionals call the “banana effect.”

The V Axis (Crowning Axis) is the ultimate solution to this challenge. It works by applying a counteracting force beneath the table, preloading it with a precise upward curvature that perfectly neutralizes the deformation occurring during bending. As a result, the upper and lower dies remain perfectly parallel when under pressure.

(1) Hydraulic vs CNC Mechanical Compensation: A Comprehensive Balance of Performance, Accuracy, and Cost

Currently, two main methods are used for V-axis compensation, and choosing between them involves weighing precision, consistency, and long-term cost:

(2) Inside the Compensation Formula: How the System Calculates and Applies the Perfect Value Automatically

You might wonder how the CNC system knows exactly how much compensation to apply. Behind this lies an intelligent algorithm built from material mechanics and extensive experimental data. No manual calculations are required—simply input four key parameters into the CNC controller:

• Material Type (e.g., mild steel, stainless steel)
• Sheet Thickness (t)
• Bending Length (L)
• Lower Die Opening Width (V)

The CNC controller then performs a sequence of operations:

Database Lookup: Retrieves material tensile strength from its internal database.

• Force Calculation: Uses its built-in formula to estimate the tonnage required for the bend.
• Deflection Curve Matching: Each machine is calibrated at the factory using laser interferometry, which records its deflection profile at various load levels and stores it in the controller.
• Command Execution: Based on the calculated tonnage, the controller matches the corresponding deflection (e.g., 0.15 mm) and instructs the V axis—hydraulic or mechanical—to generate an upward curve of +0.15 mm.

This entire process completes automatically before you even press the bending pedal, ensuring every bend is perfectly compensated.

2. Delta X-Axis: Independent Backgauge Finger Movement

If a six-axis configuration already addresses most needs, why add more—eight, ten, or even higher? The answer: to achieve total automation efficiency and eliminate the last traces of manual intervention.

A typical eight-axis setup includes Y1/Y2, X1/X2, R1/R2, Z1/Z2. The X1/X2 and R1/R2 axes give each backgauge finger independent movement not only sideways (Z-axis) but also forward/backward (X-axis) and up/down (R-axis). This allows single-pass positioning for parts with differing flange depths or heights across both ends, removing the need for manual rotation or dual positioning.

Advanced axes like Delta-X (also called X-Prime) take this capability even further. They allow the backgauge fingers to make fine lateral movements or offset the entire backgauge beam relative to the ram centerline.

Application Scenario: When bending an angled line relative to the sheet edge, the Delta-X axis can position one finger slightly forward and the other backward, tilting the sheet precisely for angled bends.

(1) Decision Framework: Assessing Workpiece Complexity to Justify Investment in Eight Axes or More

Adding more axes should never be about chasing numbers—it’s a clear matter of cost-benefit rationalization. Below is a simplified decision framework:

1）If your products are standard boxes or simple brackets:

A 4-axis + V-axis (4+1) setup delivers excellent efficiency.

2）If your products frequently involve uneven flange widths or asymmetrical geometries:

Six axes become essential. Z1/Z2 alone save considerable manual adjustment time.

3）If your key products require bending multiple flanges of varying depths and heights along a single long sheet:

Investing in an 8-axis system (X1/X2, R1/R2) pays off hugely by consolidating multiple setups into one operation.

4）If your core business involves angled bends, tapered cylinders, or fully automated “lights-out” production:

Then 10-axis or higher systems with Delta-X and other advanced axes represent the ultimate solution.

(2) Think of Axis Count as “Purchased Degrees of Freedom”

Industry insider tip: Don’t treat axis count as just a number—it’s essentially your purchase of motion freedom. In robotics, Degrees of Freedom (DoF) define an arm’s flexibility; every additional axis on a press brake adds one more dimension of controllable movement.

Each added degree of freedom directly translates into less manual intervention and more time saved.

• The freedom provided by the Z1/Z2 axes eliminates the need for operators to manually reposition the backgauge fingers.
• The freedom of the R axis removes the need for manually raising or lowering the beam.
• The freedom of the X1/X2 axes replaces the operator’s manual adjustment for different flange depths during secondary positioning.

Each additional axis represents a one-time capital investment that replaces ongoing, costly, and error-prone manual operations and waiting time. This is the true core of the ROI logic behind multi-axis systems—and the key insight that transforms you from a "manager" into a "strategic profit architect."

VI. Configuration and Selection

1. Minimum Configuration

For basic operations, a CNC press brake machine must have at least one Y-axis, which controls the vertical movement of the ram. A more common and versatile configuration is the three axis setup, which includes:

• Y-Axis (y1 and y2 axes): Controls the vertical movement of the ram. Independent control of Y1 and Y2 enhances precision and is particularly useful for asymmetrical parts.
• X-Axis: Manages the horizontal movement of the backgauge, ensuring accurate positioning of the workpiece.
• R-Axis: Governs the vertical movement of the backgauge fingers, accommodating different flange heights and material thicknesses.

For example, a 3-axis setup can efficiently handle basic bending tasks such as creating uniform 90-degree bends in sheet metal for simple brackets.

2. Advanced Axis Configurations

For more complex bending tasks and increased precision, additional axes can be integrated into the CNC press brake machine. These advanced configurations include:

• Z-Axis (Z1 and Z2): Controls the lateral movement of the backgauge fingers. Independent Z1 and Z2 axes allow for precise positioning of each backgauge finger, essential for complex parts.
• Delta X-Axis: Enables independent horizontal movement of each backgauge finger along the X-axis. This is particularly useful for handling asymmetrical workpieces and creating complex bends.
• Crowning Compensation (V-Axis): Adjusts for deflection in the press brake bed during bending, ensuring uniform pressure distribution and consistent angle of the bend.

For instance, creating intricate, multi-bend components with varying angles and dimensions would require the precision and flexibility provided by these additional axes.

3. Selecting the Right Number of Axes

When deciding on the number of axes for your CNC press brake, consider the following factors:

Complexity of Workpieces

If you frequently work with complex or asymmetrical parts, additional axes like Z1/Z2 and Delta X are essential. These axes provide the flexibility and precision needed to handle intricate bends and varying angles.

Precision Requirements

Higher precision requirements necessitate more advanced configurations. Independent control of Y1 and Y2, combined with crowning compensation, ensures that even the most demanding bends are executed with accuracy.

Production Volume

For high-volume production, a CNC press brake with multiple axes can significantly reduce setup times and increase throughput. Automated backgauge adjustments and precise positioning minimize manual interventions, enhancing overall efficiency.

4. Balancing Cost and Capability

While additional axes enhance the functionality and precision of a CNC press brake, they also increase the machine's cost. It's important to balance your budget with your operational needs:

• Basic Configuration: Suitable for straightforward bending tasks and smaller budgets. A 3-axis setup (Y1/Y2, X, R) provides a good balance of functionality and cost.
• Intermediate Configuration: Ideal for moderate complexity and precision requirements. Adding Z1/Z2 axes to the basic setup offers greater flexibility without a significant cost increase.
• Advanced Configuration: Necessary for high-precision and complex bending operations. Incorporating Delta X and crowning compensation (V-axis) into the setup ensures top-tier performance but at a higher cost.

In summary, the number of axes of the press brake determines the complexity and accuracy of the workpiece. However, the more axes, the higher the cost of machine procurement. If there are no complex bending requirements, only a basic 3-axis or 4-axis press brake is required. If complex and precise workpieces need to be processed, the more the number of axes, the better the bending effect.

VII. FAQs

1. What is a 4 axis press brake?

A 4 axis press brake is a machine tool that is used to bend sheet metal and plate. It consists of a stationary bed and a moveable ram, which is equipped with a punch that is used to apply pressure to the workpiece. The workpiece is held in place by a set of dies, which are mounted on the bed of the press brake.

2. What is the Z1 and Z2 axis?

Z1 is the left and right moving axis of the left back gauge finger. Z2 is the left and right moving axis of the right back gauge finger. If your work piece is very small or you need to adjust the width of the stop finger frequently, the programmable z-axis is very time-saving and labor-saving.

3. What is CNC press brake vs NC press brake?

CNC press brakes are generally more advanced than NC press brakes and offer greater accuracy and higher-quality products. However, NC press brakes have a high cost-performance ratio and are more affordable than CNC press brakes. Yet, they still possess complete functions and high bending accuracy.

VIII. Conclusion

The bending accuracy of a press brake is determined by the movement of its axes. A press brake should have at least one Y-axis to control the up and down movement of the ram. The Y-axis is the most important axis because it controls the bending angle of the workpiece. The most common press brake is the 3-axis configuration, which is equipped with Y1/Y2, X, and R axes.

When purchasing a press brake, it's important to select the appropriate number of axes based on the complexity of the workpiece. ADH is a professional press brake manufacturer. Our product experts can help you select the most suitable press brake for your budget. Our product experts can help you select the most suitable press brake for your budget. To learn more about our machine specifications, please download our brochures, or contact us directly for a personalized consultation.

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