88 ° and 90° Bend Allowance Chart

What is bend allowance?

Bending allowance is statistical data which summed up by experienced mold designers based on years of experience. The later mold designers can directly put the data into the formula to calculate the unfold size of various sheet metals.

Therefore, press bend allowance is summarized for calculating unfold dimensions for mold designers.

The functions of bend allowance

The one who has designed the punch mold all know that the first step is to expand the bend structure into flat structure in reverse way step by step when get the product drawings from the customers and began to design mold drawing. Then punching the flat structure and design the bending mold based on above process so as to meet customer’s requirements.

As a mold designers, the structure design of the mold not only need to consider the customer drawings requirements, also need to meet customer requirements of drawing dimension tolerance requirements, namely the precision also need to meet customer demand.

The most difficult thing here is to guarantee the accuracy of the relevant unfold dimensions of stamping bending.

Bend allowance chart

ItemMaterialThicknessDeductionInside RAngleDiePunch
RadiusV WidthRadiusAngle
1Steel Plate0.81.501.390°0.580.288°
2Steel Plate0.91.701.390°0.560.288°
3Steel Plate1.01.801.390°0.580.288°
4Steel Plate1.21.911.090°0.460.288°
5Steel Plate1.22.101.390°0.580.288°
6Steel Plate1.52.501.390°0.580.288°
7Cold Rolled Plate1.62.651.390°0.580.688°
8Cold Rolled Plate1.83.402.090°0.8120.688°
9Cold Rolled Plate2.03.502.090°0.8120.688°
10Cold Rolled Plate2.33.752.090°0.8120.688°
11Cold Rolled Plate2.54.202.690°0.8160.688°
12Cold Rolled Plate3.05.052.690°0.8160.688°
13Cold Rolled Plate4.06.904.090°0.8250.688°
14Hot Rolled Plate2.33.772.690°0.8160.688°
15Hot Rolled Plate3.25.202.690°0.8160.688°
16Hot Rolled Plate4.27.404.090°0.8250.688°
17Hot Rolled Plate4.88.104.090°0.8250.688°
18Aluminum Plate0.81.501.390°0.560.288°
19Aluminum Plate1.01.601.390°0.580.288°
20Aluminum Plate1.22.101.390°0.580.288°
21Aluminum Plate1.52.451.390°0.580.288°
22Aluminum Plate1.62.701.390°0.580.688°
23Aluminum Plate1.62.401.390°0.6100.688°
24Aluminum Plate2.03.252.090°0.8120.688°
25Aluminum Plate2.33.602.690°0.8160.688°
26Aluminum Plate2.54.202.690°0.5160.688°
27Aluminum Plate3.04.702.690°0.8160.688°
28Aluminum Plate3.25.002.690°0.8160.688°
29Aluminum Plate3.55.904.090°0.8251.588°
30Aluminum Plate4.06.804.090°0.8251.588°
31Aluminum Plate5.08.104.090°0.8253.288°
32Copper Plate0.81.601.390°0.560.288°
33Copper Plate1.01.901.390°0.580.288°
34Copper Plate1.22.151.390°0.580.288°
35Copper Plate1.52.551.390°0.580.288°
36Copper Plate2.03.502.090°0.8120.688°
37Copper Plate2.54.202.690°0.8160.688°
38Copper Plate3.05.002.690°0.8160.688°
39Copper Plate3.25.102.690°0.8160.688°
40Copper Plate3.56.004.090°0.8251.588°
41Copper Plate4.07.004.090°0.8251.588°


Calculate unfold size with bend allowance chart

Bend Allowance Chart

Bend forming 0°L=A+B-0.43T, T=Thickness, Deduction=0.43T

Fomula: L(unfold length)=A(Outside size)+B(Outside size)-K(K-factor)

None-90° bend unfold according to neutral layer, the distance from neutral to sheet inner side is T/3, inner R can refer to above chart.

V-die width is 6-8 times the plate thickness, None-90°bend = 180°- Angle/90°*Deduction

Deduction is 1.8 times the steel plate thickness and 1.6 times the aluminum plate.

For plate under 2mm, K-factor is 0.432, R=plate thickness, unfold size can accurate to 0.05.

Generally, when design the sheet metal parts, the min inner R=thickness/2, if less than that, grooving (V-cutting) will be required to solve the problem.

2018-01-12T10:00:31+00:00 Bending|

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