I had a question on k factors for our 3 d modeling software.
Neutral line in sheet metal.
Notice how the sheet has thinned at the bend.
When you bend sheet metal the neutral axis shifts toward the inside surface of the bend.
Basically the k factor offsets the neutral line to provide a flat pattern that reflects reality.
The neutral axis position depends on the bend angle inside bend radius and method of forming.
The neutral line is an imaginary line that passes somewhere close to the middle of the material.
Look closely a figure 1.
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The neutral line also called the neutral axis is an imaginary line that can be drawn through a cross section of the workpiece that represents the locus where no tensile nor compressive stresses are present on the work.
The line where the transition from compression to stretching occurs is called the neutral axis.
And by having t and the sheet thickness t we can calculate the k factor as follow.
A is the bending angle in the above equation so.
By using it you get the bend allowance which is in essence the length of the curved neutral axis.
The k factor in sheet metal working is the ratio of the neutral axis to the material thickness.
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Satin nick elliptical aluminum sheet model 57010 18 98 18 98.
It varies according to material its thickness bend radius and bending method.
The k factor is the ratio of the neutral axis location t to the material thickness mt.
This thinning of the bend area moves the neutral line of the metal in towards the radius center.
22 gauge metal sheet model 801447 8 98 8 98.
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The location of the neutral axis varies and is based on the material s physical properties and its thickness.
Figure 2 after bending the bend area is 10 to 15 percent thinner than before bending.
When metal is bent the top section is going to undergo compression and the bottom section will be stretched.
The neutral axis is the zone or plane that separates the tension from the compression.
Its location in the material is a function of the forces used to form the part and the material yield and tensile strengths.
Our design engineers typically use a factor of 0 4 for our air formed press brake parts.
If the material did not stretch at all then the neutral line would be at 50 of the material.
It is the area where the material neither stretches nor compresses in the bend.
The neutral axis s behavior is the main reason the flat part needs to be smaller than the total of the formed piece s outside dimensions.
To calculate the neutral axis distance from the inner face t we can subtract inside bend radius from r.
