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Steel Sheet Bending Complete Guide 2026
Time:2026-02-09     
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Steel sheet bending may seem similar to bending ordinary carbon steel, but in reality, it presents many challenges: high springback, easy scratching, inaccurate angles, and rapid die wear.

Below, we provide a complete, workshop-level guide, organized by principle → process → die → parameters → operating techniques → common problems → practical tips.

 

1. The "Essential Difficulties" of Steel Sheet Bending


CNC press brake steel sheet bending


First, understand why it's difficult to bend:


1) High Springback (Core Issue)

Stainless steel has high yield strength and low elongation. Springback is typically 30%–60% greater than carbon steel. This is more pronounced in harder materials (304H, 316L, duplex steel).

 

2) High Surface Requirements

Brushed/mirror/coated finishes are easily damaged by a single scratch, resulting in extremely high rework costs.

 

3) Rapid Die Wear

Stainless steel is "very unfriendly" to dies. Ordinary dies experience a lifespan reduction of over 40%.

 

2. Key Confirmations Before Steel Plate Bending


1) Material Grade

Grade

Bending difficulty

Characteristics

201

★★☆☆

Hard, high resilience

304

★★★☆

Most commonly used

316/316L

★★★★

High toughness, obvious resilience

430

★★☆☆

Brittle, easily cracked

Pay close attention to the minimum bending radius for 201 and 430.

 

2) Plate Thickness Tolerance

The thickness fluctuation of stainless steel plates is greater than that of carbon steel. A thickness difference of 0.1 mm within the same batch is very common. Actual measurement is essential before press brake bending!

 

3) Grain Direction (Critical Detail)

Bending line ⟂ Rolling direction → Optimal

Bending with the grain → Prone to cracking, unstable angle

Especially important for brushed steel plates.

 

3. Die Selection for Stainless Steel Bending


Steel sheet bending process


1) Formula for Selecting the V-groove of the Lower Die

Stainless steel must use a "large V" groove.

Plate thickness t

Recommend V-groove

t ≤ 1.5 mm

8t~10t

2–3 mm

10t~12t

4–6 mm

12t~14t

≥8 mm

14t~16t

Insufficient V-groove = high springback + surface damage

 

2) Key Points for Upper Die Selection

Rounded corner upper dies are preferable to sharp corner dies.

Upper die radius ≥ 1.0~1.5 × plate thickness.

Chrome-plated/polished upper dies are preferred.

Sharp corner dies are prohibited for mirror-finish plates.

 

3) Recommended Die Material

42CrMo ≥ Ordinary T8

High-frequency quenching, surface hardness ≥ HRC52.

 

4. Stainless Steel Bending Process Parameter Settings


1) Optimal Bending Method

Process

Recommendation

Note

Free bending

⭐⭐⭐⭐

Preferred choice

Correction bending

⭐⭐

High risk of crush injury

Bottoming bending

Unless specifically requested

2) Steel Sheet Bending Pressure

Stainless Steel ≈ Carbon Steel × 1.3~1.5

Example:

Carbon Steel 2mm: 20 tons

Stainless Steel 2mm: 26~30 tons

 

3) Angle compensation (empirical value)

Target angle

Actual settings

90°

86°~88°

60°

56°~58°

120°

124°~126°

 

5. Stainless Steel Plate Bending Operation Techniques (Workshop Tips)


1) Bending Sequence

Larger angle first → Smaller angle later. Inward fold first → Outward fold later.

Avoid "dead corners" that prevent part removal.

 

2) Anti-Scratch Techniques (Very Practical)

Laminated sheets with the film facing outwards.

Apply nylon tape/PVC protective strip to the lower die.

For mirror-finished sheets, use kraft paper/Teflon film.

 

3) Preventing Angle Deviation in Long Workpieces

Deflection compensation is essential for workpieces over 2m in length.

Point bend in the middle first → correct at both ends.

 

4) Lower Die V-groove

Larger is better than smaller.

Smaller V-groove → Greater springback + heavier indentation.

Recommended: V = 10~12 × sheet thickness

 

5) Reverse Springback Method

Apply 1°~2°more pressure.

Release the die → lightly press to trim the corner.

Especially effective for thick stainless steel.

 

6. Precautions for Bending Steel Sheet



1) Pay attention to the grain direction

Bending line ⟂ Rolling direction → Most stable.

Bending with the grain → Prone to cracking, unstable angle.

 

2) The bending radius should not be too small

Too small a radius → Risk of cracking.

It is recommended that the inner radius≥the plate thickness.

 

3) Differentiate material batches

Even within the same 304 stainless steel, different batches can vary greatly.

If the batch changes, the parameters must be readjusted.

 

4) Do not use correction bending casually

Correction bending angle is accurate.

But: severe pressure damage, rapid die wear.

Unless the dimensional tolerance requirements are extremely strict.

 

5) The die must be clean

Iron filings on the lower die = indentation will inevitably remain

Mirror panels must be wiped clean before bending.

 

6) Do not apply full bending force all at once

Start with slow contact and gradually increase pressure to prevent "over-pressure".

 

7) Do not share parameters with carbon steel

Springback and pressure are completely different.

The CNC system should have a separate "stainless steel" material library.

 

7. Steel Sheet Bending Parameter Quick Reference Table (90° Free Bending)


Below is a "Steel Sheet Bending Parameter Quick Reference Table by Plate Thickness," assuming common 304/316 stainless steel, free bending, and a 90°target angle. It's ready to use immediately.

 

Applicable Conditions:

- Material: 304/316 Stainless Steel

- Bending Method: Free Bending (Non-Corrected)

- Lower Die Opening: V = 10~12 × Plate Thickness

- Upper Die: Rounded Corner Die

- Length: 1000 mm (Pressure per meter)

 

1) Plate thickness ≤ 1.5 mm

Plate thickness (mm)

Recommend V-groove (mm)

Upper die fillet radius (R)

Actual pressing angle

Bending force (t/m)

0.8

8

R1.0

87°

4–5

1.0

10

R1.0–1.5

87°

6–7

1.2

12

R1.5

86.5°

8–9

1.5

16

R2.0

86°

10–12

 

2) Plate thickness 2-3 mm

Plate thickness (mm)

Recommend V-groove (mm)

Upper die fillet radius (R)

Actual pressing angle

Bending force (t/m)

2.0

20

R2.0–2.5

86°

18–20

2.5

25

R3.0

85.5°

22–25

3.0

30

R3.0–4.0

85°

28–32

 

 

3) Plate thickness 4-6 mm

Plate thickness (mm)

Recommend V-groove (mm)

Upper die fillet radius (R)

Actual pressing angle

Bending force (t/m)

4.0

40

R4.0–5.0

84.5°

45–50

5.0

50

R5.0–6.0

84°

60–65

6.0

60

R6.0–8.0

83°

75–85

 

 

4) Plate thickness 8-12 mm

Plate thickness (mm)

Recommend V-groove (mm)

Upper die fillet radius (R)

Actual pressing angle

Bending force (t/m)

8.0

80

R8.0–10

82°

120–140

10.0

100

R10–12

81°

170–190

12.0

120

R12–15

80°

230–260

 

8. Common Problems & Solutions


steel sheet bending machine press brake


- Inconsistent bending angles?

Uneven sheet thickness → Zoning parameters

Lower die V-shape too small

Machine deflection compensation not activated

 

- Cracks at the bending point?

Bending radius too small

Follow-grain bending

430/201 material issue

 

- Severe surface indentations?

Lower die groove too small

Die not polished

Excessive correction pressure

 

- Bending line deviation?

Inaccurate back gauge

Sheet material not properly adhered

Upper die wear


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