How Wide Should Steel Be Pre-Bending for a 21 Finish with a 1 Lip?

[badgermanb]

I need a piece of .125" steel sheet metal to be 21" wide after a 1" lip is bent to 90 degrees on one side. How wide does the initial piece of steel need to be before bending in order to achieve this? I know it will be more than 22", but how much more?

If I recall its fairly simple to figure out I just can't remember how to do it. Thanks

 

[nucleus]

Try:
http://www.engineersedge.com/bend_allow_calc.htm

 

[badgermanb]

Thanks that works perfectly.

 

[spacester]

Excellent reference.

Note that the median fiber is not necessarily at the middle of the thickness. The actual machine doing the bending is going to dictate just where that median fiber is. You may very well find that it was closer to 1/3 from the inner surface than 1/2.

 

[alphy]

I would approach this question by first considering the properties of the material being used. The thickness of the sheet metal, in this case .125", is an important factor in determining the required width before bending. This is because thicker materials require more bending force and therefore will result in a wider final product.

In order to calculate the necessary width, we can use a formula called the K-factor, which takes into account the thickness of the material and the radius of the bend. The K-factor can vary based on the specific material and bending process being used, but a general value of 0.5 can be used for this calculation.

Using the K-factor of 0.5, we can calculate the bend allowance, which is the amount of material consumed during the bending process. In this case, the bend allowance would be equal to the thickness of the material, 0.125", multiplied by the K-factor, resulting in a bend allowance of 0.0625 inches.

To determine the required initial width, we can use the following formula:

Initial width = Desired final width + 2 x Bend allowance

In this case, the desired final width is 21 inches and the calculated bend allowance is 0.0625 inches. Plugging these values into the formula, we get:

Initial width = 21 inches + 2 x 0.0625 inches = 21.125 inches

Therefore, the initial piece of steel needs to be at least 21.125 inches wide before bending in order to achieve a final width of 21 inches with a 1 inch lip bent at 90 degrees. However, it is always recommended to add a slight margin of error to account for any variations in the bending process, so a width of 21.25 inches would be a safer choice.

I hope this information helps in your sheet metal bending process. It is important to always consider the properties of the material and use appropriate calculations to ensure accurate and efficient results.