Factors Affecting the Quality of Bending Machine Dies

First, product design must be rational, with preference given to superior structural solutions. The design of press brake dies is a critical step in enhancing die quality; product designers should take into account both the technical requirements and the overall structure of the part, ensuring that the design is technically sound and feasible for die manufacturing. Many factors need to be considered. Let’s now explore the key factors that contribute to improving press brake die quality.

Selection of Die Materials for Bending Machines

Usability of the press brake die structure

Safety of Bending Dies

Machinability of Bending Machine Die Components

Ease of maintenance for press brake dies

These must be considered as comprehensively as possible from the very beginning of the design.

1. Material Selection

The selection of die materials for press brakes must not only meet the quality requirements of the customer’s products, but also be based on factors such as the type of press brake die, its mode of use, processing speed, and predominant failure modes. In addition, material cost and strength over the specified service life must be taken into account.

2. Structure

When designing the structure of a press brake die, strive for a compact layout and ease of operation, while ensuring that the die components possess adequate strength and stiffness.

If the design permits, every corner of a part should be rounded and smoothly transitioned as much as possible to avoid stress concentrations. Long, slender punches or cores must be provided with appropriate structural safeguards. Cold dies should be equipped with devices to prevent product or scrap from causing blockages. For female dies, cavities, and certain punches and cores, combined or insert-type structures may be employed to eliminate stress concentrations and reduce the scope of disassembly and reassembly when repairing individual components—particularly when replacing wear-prone parts. At the same time, measures should be taken to minimize the impact of wear on the quality of press brake dies resulting from long-term use of bent-and-mated parts and frequently colliding components; accordingly, the extent of their disassembly and reassembly should be reduced as much as possible.

3. Manufacturing and Assembly

The manufacturing process is also a critical step in ensuring the quality of press brake dies; the dimensional accuracy of individual components directly affects the overall assembly and performance of the die. In addition to minimizing the influence of the machine tool’s inherent accuracy, improvements have been made to the machining methods for the components. Moreover, the machining techniques and precision employed during manufacturing significantly impact the service life of the press brake die, necessitating the enhancement of fixture technology in the grinding process to improve the dimensional accuracy of die components.

When the overall assembly performance fails to meet the requirements, in order to ensure that the press brake die maintains its original high precision—i.e., its initial quality—the probability of the die operating under abnormal conditions during the trial-manufacturing phase is relatively high, which can severely compromise the die’s overall quality. Therefore, during the manufacturing process, it is essential to first select appropriate high-precision machining methods, such as electrical discharge machining, wire EDM, and CNC machining.

At the same time, attention must be paid to precision inspection; whenever possible, high-precision measuring instruments should be used. For parts with complex surface and curved geometries, conventional straightedges and vernier calipers cannot provide accurate measurement data. Therefore, comprehensive precision assessment should be conducted through trial manufacturing and inspection, covering both machining accuracy and assembly accuracy. Precision measurement equipment, such as three-coordinate measuring machines, should be employed to ensure the accuracy of measurement data.

4. Surface Strengthening

Surface hardening should be applied to the primary forming parts to enhance surface wear resistance and thereby improve overall quality; the specific hardening method employed should be selected based on the intended application of the bending machine tooling.

For example, blanking dies can be subjected to electrical-discharge hardening or cemented-carbide surfacing, which can enhance the wear resistance, thermal-fatigue resistance, and wear-corrosion resistance of the parts. For drawing dies and bending dies, sulfurizing treatment can reduce the coefficient of friction and improve the surface wear resistance and compressive strength of the parts. For die components—such as those used in hot-forming and bending operations in plastic-molding dies—nitriding (hard nitriding) is employed to improve material wear resistance; carbonitriding (soft nitriding), on the other hand, can be applied for surface strengthening of molds supplied by various vendors.

5. Proper Use and Maintenance

Proper use and maintenance of press brake dies are also critical factors in enhancing die quality. For instance, the installation and adjustment procedures must be appropriate; when a hot runner system is employed, the power wiring must be correctly connected; the cooling water circuits must comply with design specifications; and during production, the operating parameters of injection molding machines, die casting machines, and presses must all meet the design requirements.

Proper use of press brake dies also requires regular maintenance. Before each forming operation, a lubricant or release agent should be applied to the surface of the formed part; planned preventive maintenance should be carried out, along with data collection and analysis during maintenance. Lubricating oil should be frequently applied to guide posts, guide bushings, and other components with relative motion. For die-casting dies, plastic molds, and other types of press brake dies, such practices can help prevent potential production issues and enhance the efficiency of maintenance operations.

In summary, to improve the quality of press brake dies, it is essential to first consider the factors that influence die quality.