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How to calculate the min bending edge of sheet metal

  1. L Bending

Min. L bend factors 

V groove center is vacant while shaping, so the ridge crease should be longer compared to vacant part and a certain landing ridge depends on various manufacturers. If the below part of V groove is exposed to use quite long, then R bevel rises, this consequently brings about scrap ridge space expansion or else slipping occurs.

  1. Contraction formula (experiential) 6*T/2+0.5+(1.8*T/2) 
  2. As visible in the depiction in case T is 1, K is 1.8*1, the least L bend will be 3+0.5+0.9=4.4
V Groove/Thickness34567891012151618

2 The least U bend factors

Punch Forms

In terms of punching molds, the most suitable for U bend is goose neck like punch. This can be of various sorts. See in the depiction .

Bend Size

Here exists interrelated connection within both sizes.

The length of B depends on A length. If it is longer, B will also be long.

Contraction formula (experiential value of goose-neck punch)

0.5 mm plate:

Min. U bend- A equals 7.67, B equals 0.5, min. L bend equals 3.0

Rising value- In case A enlarges by 1 mm, B rises up to 1.87.

Formula is as the following: In case A is apparent, B equals A-7.67/ T* rising value + min.sheet L bend value . For instance, A=15 B will equal (15-7.67)/0.5*1.87+3.0=30.4

In case B is apparent, A will equal B-the least L bend value of the sheet/rising value* T+7.67

For instance, B is 30.4, A is 30.4-3/1.87*0.5+7.67=15

Plate of 0.8 mm

The least U bend A equals 8.5, B equals 0.8, minimum L bend is 4.2.

Rising value is 1.87/0.5*0.8=2.99

Plate of 1.0 mm

The least U bend A equals 8.94, B equals 1.0, least L bend is 4.5

Rising value is 1.87/0.5*1.0=3.7

Plate of 1.2 mm

Least U bend A is 9.3, B is 1.2, least L bend equals 4.5

Rising value is 1.87/0.5*1.2=4.5

Plate of 1.5 mm

The least U bend A equals 10.3, B is 1.5, least L bend equals 6.2.

Rising value is 1.87/0.5*1.5=5.5

Plate of 2.0 mm

The least bend size equals 12.7, B is 2.0, least L bend equals 12.0

Rising value is 1.87/0.5*=7.4


In case A is more than 85.0 mm, B is more than 60.0 mm the given formula cannot be applied.

Given chart implies that A equals test value, B equals the least L bend and K equals test value.

ThicknessA size (min)B size (min)K

Z Bend Types

In case H exceeds or is equal to 5T, calculation is per 90 degrees. 

In case it is less than 5T, shaping once is sufficient.

Major affecting ratios for the least Z bend value are V grooving breadth as well as its length from middle to the ridge.

Formula is going to be 6*T/2+ridge space from V grooving + (1.8*T/2)+T

If sheet metal is of 1.0 mm density, ridge space is 1.5, the least Z bend H equals 6*1/2+1.5+(1.8*1/2)+1= 6.4

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