13 avril 2007

Sheet Metal Bending Calculator

Sheet Metal Bending Calculator

Sheet Metal Bending Calculator

Sheet Metal Links:
The Tinbasher Sheet Metal Blog

MARTINDALE'S CALCULATORS

Disclaimer: I am not responsible for errors in this program. It's as good as I can make it. But I'm human I make mistakes.

Part 1: Radius calculations for easy developed length

A drawing convention at Wabash in Laffayette is to set the developed length of a sheet metal part to the sum of the inside to inside measurements and then to set the size of the radius of each bend to fit based on a formula derived from the developed length formula. This only applies to 90° angles.

The formula is:
radius = constant * thickness / ( 2 - pi / 2 )

The minimum bend radius

The minimum radius given in step 6 calculates the limit of bending where cracking or splitting will occur. For accuracy the calculated developed length and the calculated real outer radius formulas were used in the minimum radius formula development.

Part 2: the developed length

The developed length formula is simple:
developed_length = (angle / 90) * (material_constant * thickness + pi * radius / 2)

The outside radius

An added feature of this program is the calculation of the outside radius. In most instances the outside radius can be set as the sum of the thickness and the inside radius. This is close but not technically correct. As the metal bends more of the material stretches across the outside of the bend then compresses on the inside of the bend thus the developed length (the length of material cut before bending) is usually less then the final length. If the material were longer after bending then before and the thickness was constant throughout then there would be more cross sectional area after the bend. That would defy the law of constancy of matter. Generally bends are slightly thinner the rest of the part. This didn't matter until finite element analysis arrived. If you want the best FEA results use the most realistic geometry in your model. The calculated outside radius below should produce a bend with the same cross sectional area as before it was bent.

To use the outside radius make an concentric arc for the outside of bend and blend to the normal thickness area.



Part 1: Radius calculations for easy developed length and the minimum bend radius

  1. Enter the thickness of the sheet metal:
    (use the same units for all of these: i.e. inches in inches out.)
  2. Enter the material constant (.71 for steel .683 for aluminum)
  3. Enter the percent elongation for this material (i.e. 2 = 2%): %
  4. Click this button:
  5. The radius is:
  6. The minimum radius is:

Part 2: the developed length and the outside radius

  1. Enter the thickness of the sheet metal in step 1 above.
  2. Enter the material constant (.71 for steel .683 for aluminum) in step 2 above.
  3. Enter the inside radius to use in step 5 above.
  4. Enter the angle bent in degrees: °
  5. Click this button:
  6. The developed length is:
  7. The outside radius for the radius in step 5 is:

Disclaimer: I am not responsible for errors in this program. It's as good as I can make it. But I'm human I make mistakes.



The following charts may be helpful:

Some common elongation values
Description Elongation
1010 Hot Rolled steel 30-40%
1010 Cold Drawn steel 20-30%
1020 Hot Rolled steel 26%
A36 steel 5/16 to 3.5 thick 23%
A36 steel 9/32 thick 21.75%
A36 steel 4/16 thick 20.5%
A36 steel 7/32 thick 19.25%
A36 steel 3/16 thick 18.%
A36 steel 5/32 thick 16.75%
A36 steel 2/16 thick 15.5%
A36 steel 3/32 thick 14.25%
A36 steel 1/16 thick 13%
A36 steel 1/32 thick 11.75%
Aluminum 3004-H36 5%
Aluminum 5052-H34 10%
Aluminum 5454-H34 10%


HOT ROLLED STEEL THICKNESS CHART
MFRS. GAGE REF. WEIGHT (LB/SQIN) NEW MIN. TOTAL TOL. REFERENCE MILL DATA
95% MIN. 90% EXPECTANCY
EXPECT. LOW HIGH
.375 .103 .362 +.028 .365 .366 .372
2 .067 .238 +.024 .240 .242 .248
3 .064 .227 +.020 .229 .230 .237
4 .061 .215 +.020 .217 .218 .225
5 .057 .200 +.020 .202 .203 .209
6 .052 .185 +.020 .187 .187 .193
7 .048 .171 +.016 .173 .173 .179
8 .044 .156 +.016 .158 .158 .164
9 .040 .142 +.016 .144 .144 .150
10 .036 .126 +.016 .128 .128 .134
11 .032 .112 +.016 .113 .114 .119
12 .027 .097 +.014 .098 .099 .104
13 .023 .081 +.014 .083 .083 .088
14 .020 .071 +.012 .072 .073 .076
15 .018 .063 +.012 .064 .064 .068
16 .016 .056 +.008 .057 .057 .061



COLD ROLLED STEEL THICKNESS CHART
MFRS. GAGE REF. WEIGHT (LB/SQIN) NEW MIN. TOTAL TOL. REFERENCE MILL DATA
95% MIN. 90% EXPECTANCY
EXPECT. LOW HIGH
9 .040 .142 +.012 .143 .144 .148
10 .036 .126 +.012 .127 .128 .132
11 .032 .112 +.012 .113 .114 .118
12 .027 .097 +.012 .098 .098 .102
13 .023 .081 +.010 .082 .082 .086
14 .020 .071 +.010 .072 .072 .075
15 .018 .063 +.010 .064 .064 .067
16 .016 .056 +.008 .057 .057 .060
17 .014 .050 +.008 .051 .051 .053
18 .012 .044 +.008 .045 .045 .047
19 .011 .038 +.006 .038 .039 .041
20 .009 .033 +.006 .033 .034 .035
23 .007 .024 +.006 .024 .025 .026
24 .006 .021 +.006 .021 .022 .024
25 .005 .018 +.004 .018 .019 .020



GALV. COMMERCIAL H.S. OR STRUCTURAL STEEL THICKNESS CHART
MFRS. GAGE REF. WEIGHT (LB/SQIN) NEW MIN. TOTAL TOL. REFERENCE MILL DATA
95% MIN. 90% EXPECTANCY
EXPECT. LOW HIGH
7 .045 .160 +.018 .161 .162 .167
8 .044 .156 +.018 .157 .158 .162
9 .040 .142 +.018 .143 .144 .148
10 .036 .126 +.018 .127 .128 .132
11 .032 .112 +.018 .113 .114 .118
12 .027 .097 +.016 .098 .099 .102
13 .023 .081 +.016 .082 .083 .086
14 .020 .071 +.016 .072 .073 .075
15 .018 .063 +.012 .064 .064 .067
16 .016 .056 +.010 .057 .057 .060
17 .014 .050 +.010 .051 .051 .054
18 .012 .044 +.010 .045 .045 .048
19 .011 .038 +.008 .039 .039 .042
20 .009 .033 +.008 .033 .034 .036
23 .007 .024 +.006 .024 .025 .026
24 .006 .021 +.006 .021 .022 .024
25 .005 .018 +.006 .018 .019 .020

STAINLESS STEEL THICKNESS CHART
MFRS. GAGE REF. WEIGHT (LB/SQIN) NEW MIN. TOTAL TOL. REFERENCE MILL DATA
95% MIN. 90% EXPECTANCY
EXPECT. LOW HIGH
6 .052 .185 +.014 .187 .187 .193
7 .048 .171 +.014 .173 .173 .179
8 .044 .156 +.014 .157 .158 .164
9 .040 .142 +.012 .143 .144 .148
10 .036 .126 +.010 .127 .128 .132
11 .032 .112 +.010 .113 .114 .118
12 .027 .097 +.008 .098 .098 .102
13 .023 .081 +.008 .082 .082 .086
14 .020 .071 +.006 .072 .072 .075
15 .018 .063 +.006 .064 .064 .066
16 .016 .056 +.006 .057 .057 .059
17 .014 .050 +.006 .051 .051 .053
18 .012 .044 +.006 .045 .045 .047
19 .011 .038 +.004 .039 .039 .040
20 .009 .033 +.004 .033 .034 .035
23 .007 .024 +.003 .024 .025 .026
24 .006 .021 +.003 .021 .022 .023
25 .005 .018 +.003 .018 .019 .020

Disclaimer: I am not responsible for errors in this program. It's as good as I can make it. But I'm human I make mistakes.

From: Joe Mansheim 5/11/99

Posted by strudel at 22:33

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2 comments:

California Sheet Metal a dit…

Useful calculator! Just wanted to say thanks!

15 mai 2008 13:38
Midwest Metal Products a dit…

Interesting!

The use of this calculator is a bit complex, but I find it very useful. Thanks for sharing this information!

17 avril 2009 02:54

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