BEND TOOLING INC.: RotaryDraw TubeBending Tools ~ Die Sets ~ Mandrels ~ Wipers ~ MandrelBending Tools 

Formulas 



Useful Formulas and Tables For Tube Bending
As discussed throughout this website, tubebending is no more a "black art" than any other metalforming process. To the extent that shopfloor experience and rules of thumb genuinely remain important keys to successful tubebending is a consequence of certain bodies of data have yet to be collected about this important manufacturing process rather than anything that is inherently resistant to standardization. Where solid data is available, the process of tubebending  especially the highly controlled rotarydraw method  is reducible to mathematical equations.
Therefore, we have grouped together all of the formulas and tables that are commonly encountered or particularly useful in tubebending under three sections: Bending Formulas, Geometric Formulas, and Conversion Formulas. Much of this information is generally applicable to tubebending without regard to method, but the focus is upon that mathematical information that is useful in setting up a rotarydraw tubebending machine. For instance, under Bending Formulas you will find those equations that are special to rotarydraw tubebending, such as the calculation for wall factor or the formula for clamp die length.
In the Geometric Formulas section are general mathematical equations and geometric principles that are applicable to tubebending, such as the Pythagorean theorem and standard formulas for calculating stress. Finally, the Conversion Formulas section contains those formulas and tables useful for translating metric values to English measures and vice versa, nominal pipe designation to true inch and metric values, among other things.
Plus we have a special section for Bend Tooling's mandrel and wiper charts. You can use these tables to specify the proper mandrel and wiper for a given combination of wall factor and "D" of bend. 
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