Selecting the right press brake tooling is crucial for ensuring bending accuracy, production efficiency, and die service life. It mainly consists of five key points:
Five Key Points for press brake tooling Selection
The key points for selecting press brake tooling are matching material characteristics, bending processes, workpiece requirements, and equipment parameters—none of which can be dispensed with. The following five key points cover all critical technical aspects of the entire selection process, ensuring both bending accuracy and die life. Beginners can directly refer to them for precise selection.
Key Point 1: Adaptation to Material Characteristics (Key to Avoiding Springback and Cracking)
Differences in Springback Characteristics of Different Metal Materials
The selection of press brake tooling must first match the tensile strength and springback characteristics of the processed material, which is the core of ensuring accurate bending angles. Ordinary mild steel has minimal springback; when bending to 90°, an 86°~88° punch can be used for compensation. Stainless steel and high-strength steel have significant springback, requiring an 85° punch or targeted adjustment of the punch angle to avoid angular deviations of the workpiece after bending.
Basic Principles for Matching Material Thickness with Dies
Material thickness directly determines the force-bearing condition and bending effect of the die. Thin, medium-thick, and thick materials require corresponding die specifications to avoid die damage or workpiece forming defects, meeting the needs of long-tail keyword searches such as "matching of material thickness and press brake tooling" on Google. The commonly used material for press brake tooling is 42CrMo, After tempering and surface induction hardening, its hardness typically reaches HRC 45-50. It has excellent strength and toughness, effectively preventing fracture under high pressure.and the following is its international standard comparison table.
42CrMo International Standard Comparison Table (Essential for Selection)
Country/Standard Organization | Standard Code | Corresponding Grade |
China (GB) | GB/T 3077 | 42CrMo or 42CrMo4 |
USA (AISI/ASTM) | ASTM A29 | 4140 |
International Organization for Standardization (ISO) | ISO 683-1 | 42CrMo4 |
Germany (DIN) | DIN EN 10083 | 1.7225 (or 42CrMo4) |
Japan (JIS) | JIS G4105 | SCM440 |
UK (BS) | BS 970 | 708M40 (EN19) |
Key Point 2: Adhere to the "8x Principle" (Selection Standard for Lower Die V-Notch Width)
Core Formula and Application Scenarios of the "8x Principle"
The "8x Principle" is the core industry formula for bending machine die selection: "Lower die V-notch width V = 8 × material thickness T". As the optimal selection standard under ideal conditions, it is applicable to bending most medium-thick plates (3-8mm), ensuring smooth bending fillets and avoiding workpiece cracking.
Adjustment Techniques for V-Notch Width of Materials with Different Thicknesses
Not all materials strictly follow the 8x Principle; the V-notch width needs to be flexibly adjusted according to material thickness: for thin plates (T＜3mm), it can be reduced to V=6T to obtain a smaller fillet radius; for thick plates (T＞8mm), it needs to be increased to V=10T~12T to reduce bending force, preventing die bursting and inner-side cracking of workpieces.
Key Point 3: Pressure Tonnage Limitation
Calculation Formula and Application of Bending Pressure Tonnage
During selection, it is imperative to ensure that the die can withstand the actual output pressure of the bending machine; overloading is strictly prohibited, as it will cause die bursting and equipment damage. The calculation of pressure tonnage needs to combine material thickness, material tensile strength, and lower die V-notch width, and the die with corresponding bearing capacity should be selected after accurate calculation.
Key Points for Matching Die Bearing Capacity with Equipment Tonnage
The actual output tonnage of the bending machine must be less than the rated bearing capacity of the die, with a certain safety margin reserved (10%-15% is recommended). For bending thick plates and high-strength steel, thickened dies or segmented dies should be selected to disperse bending pressure and extend die service life.
Key Point 4: Punch Shape Selection
Conventional Punch Types and Application Scenarios
The punch shape must perfectly match the final shape of the workpiece to avoid interference or forming defects. Different punches correspond to different bending needs: standard punches are suitable for conventional straight-edge bending and have the widest application; sharp-angle punches are suitable for small-angle bending or springback compensation; gooseneck punches are suitable for processing U-shaped grooves and deep channels, as they can avoid the already bent edges of the workpiece.
Key Points for Customizing Punches for Special Workpieces
For workpieces with circular or irregular shapes, arc punches or customized irregular punches should be selected. Combined with accurate workpiece drawings, the die contour must be completely matched with the workpiece to ensure bending forming accuracy.
Key Point 5: Installation and Equipment Compatibility
Matching of Bending Machine Die Shank Types
The die shank type must be fully compatible with the clamping system of the bending machine. Common shank types include Amada/Promecam, New Standard, and Trumpf/Wila. The equipment clamping method should be confirmed before selection to avoid problems such as insecure die installation and positioning deviation.
Adaptation Principles for Equipment Stroke and Die Height
The die height must match the slide stroke and worktable opening height of the bending machine. An excessively high die will lead to insufficient slide stroke, making it impossible to complete bending; an excessively low die will affect workpiece loading and unloading and reduce production efficiency. At the same time, the compatibility between the die installation interface and the equipment should be confirmed to ensure convenient installation and accurate positioning.
Common Misunderstandings and Avoidance Methods in Bending Machine Die Selection
Misunderstanding 1: Ignoring material springback, leading to inaccurate bending angles;
Misunderstanding 2: Failing to adhere to the "8x Principle", resulting in workpiece cracking and die damage;
Misunderstanding 3: Neglecting equipment compatibility, causing installation failures.
Press brake tooling selection
Bending machine mold selection tips
42CrMo international standard
Equivalent grades of 42CrMo
Custom press brake tooling
Why 42CrMo Is More Durable Than Ordinary Carbon Steel？
42CrMo alloy steel offers significantly higher durability compared with ordinary carbon steel, thanks to its alloy composition, heat treatment performance, and mechanical properties.
It contains chromium(Cr), molybdenum(Mo) and manganese, which greatly improve:
Higher hardness and wear resistance
Better strength and toughness
Higher tensile and yield strength
Excellent performance under high pressure and heavy load
Longer service life in industrial applications
Ordinary carbon steel is soft, wears out quickly, and deforms easily under pressure.42CrMo maintains shape, stability even under long-term heavy working conditions, making it the ideal material for press brake toolingand molds.
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