When purchasing a press brake, almost every customer asks the same core question: How thick of a plate can this machine actually bend? For the WC67K-250T/4000 — a hydraulic press brake with a nominal force of 250 tons and a working table length of 4 meters — the answer is not a single number. It depends on material type, bending length, tooling selection, and more.

This guide explains the bending force formula, provides a material-specific capacity reference table, and analyzes the key factors that affect actual processing capability — helping you make an informed selection decision.

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1. The Bending Force Formula

To determine the maximum plate thickness a press brake can handle, you first need to understand how bending force is calculated. The industry-standard formula is:

P = (650 × S² × L) / V

Where:

• P = Bending force required (unit: KN)

• S = Plate thickness (unit: mm)

• L = Bending length (unit: m)

• V = Lower die opening width (unit: mm, typically 8–10× the plate thickness)

The coefficient 650 applies to mild steel (e.g., Q235). For other materials, this coefficient must be adjusted based on tensile strength:

• Stainless steel: ≈ 1000

• Aluminum alloy: ≈ 350

Calculation Example: Bending a 1-meter-long, 5mm thick Q235 steel plate with a 40mm V-die opening:

P = (650 × 25 × 1) ÷ 40 = 406.25 KN ≈ 40.6 tons

Notice that the required tonnage is proportional to the square of the thickness — doubling the thickness from 5mm to 10mm increases the required force from ~40 tons to ~160 tons (assuming same length and tooling). This is why you must always verify with the formula rather than guessing.

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2. What Thickness Can the WC67K-250T/4000 Actually Process?

Now let’s answer the core question. This machine has a nominal capacity of 250 tons and a working length of 4 meters. We need to calculate the maximum thickness it can handle for different materials and bending lengths.

Using the formula P = (650 × S² × L) / V, and given that the lower die opening V is typically 8× the plate thickness (V = 8S), we can simplify:

P = (650 × S² × L) / (8S) = 81.25 × S × L

For a 250-ton (2500 KN) press brake, we can reverse the formula:

S_max = 2500 / (81.25 × L)

When L = 4 meters (the machine’s maximum bending length):

S_max ≈ 7.7mm (for Q235 mild steel)

This aligns with industry data we’ve gathered — a 250T/4000 press brake is typically rated for approximately 16mm steel for short workpieces, but under full 4-meter load, the Q235 carbon steel thickness limit is around 8mm, and for stainless steel, around 6mm.

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3. Material-Specific Capacity Reference Table

For quick reference, here is the maximum bendable thickness for the WC67K-250T/4000 under different materials and bending lengths (assuming air bending with standard tooling):

Important Note: The values above are theoretical calculations. Actual maximum thickness is also affected by die strength, machine rigidity, bending angle (sharp angles require more tonnage), and material consistency. We recommend leaving at least a 20% safety margin in your selection.

From this table, you can see that when bending long workpieces, tonnage is the bottleneck — when bending short workpieces, the 4-meter table becomes an advantage for processing multiple shorter parts simultaneously, boosting productivity.

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4. Three Key Factors Affecting Actual Processing Capacity

Factor 1: Lower Die Opening Selection

The lower die opening width (V) directly determines the tonnage required. A narrower opening requires more force for the same thickness; a wider opening requires less. The standard recommendation is V = 8 × plate thickness.

For example, for a 4mm plate, a V-die opening of approximately 32mm is recommended. If the available tooling deviates significantly from this, the actual processing capacity will also shift accordingly.

Factor 2: Machine Rigidity and Frame Strength

The WC67K series features a fully welded all-steel structure, normalized and high-frequency vibration-treated to eliminate internal stress, with thickened worktable and ram for high rigidity. This ensures minimal frame deflection even under full 250-ton load, maintaining straightness and angular consistency of workpieces. In practice, if you attempt to bend plates beyond the recommended thickness, excessive frame deflection can compromise accuracy and reduce tooling life.

Factor 3: CNC System and Deflection Compensation

The WC67K-250T/4000 is equipped with a CNC system that automatically adjusts backgauge and ram stroke, along with an upper die deflection compensation mechanism to offset worktable and ram deformation during bending. This means that when processing thicker plates, the compensation system can effectively improve angular consistency and reduce accuracy loss caused by machine deflection.

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5. Selection Recommendations: Which Scenarios Are Best for the 250T/4000?

Based on the analysis above, the WC67K-250T/4000 is ideal for:

1. Workpieces requiring 4-meter-long bends — such as large rack beams, steel beams, truck side panels, and other elongated sheet metal parts. The 4-meter table is not meant for bending 4-meter-long heavy plates — it’s for completing long workpieces in a single pass, reducing splicing operations.

2. Short but thick plates — if your workpieces are within 1–2 meters in length, this machine can process Q235 steel up to 14–28mm thick, suitable for pressure vessels and heavy structural components.

3. Stainless steel thick plate processing — stainless steel requires approximately 1.5× the tonnage of mild steel of the same thickness. At full 4-meter load, the stainless limit is approximately 4.5mm; with 1-meter workpieces, it can handle up to approximately 18mm.

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Summary: Select Scientifically, Match Your Real Needs

Back to the headline question — How thick of a plate can the WC67K-250T/4000 actually process?

The answer:

• Under full 4-meter load: Q235 carbon steel ~7–8mm, stainless steel ~4.5–6mm

• For short workpieces (within 1 meter): Q235 up to ~28mm

For your selection, we recommend:

1. Based on your most frequently processed workpiece material, maximum length, and typical thickness

2. Verify using the bending force formula

3. Leave at least a 20% safety margin above the theoretical limit

The strength of the 250T/4000 lies in its ability to handle both long workpieces and short thick plates — making it a versatile general-purpose press brake for a wide range of applications.