Other parameters that are linked directly with the shape and bend also affect the difficulty bending and the selection of the appropriate tools.ĭOB (Degree of bend) - the angle of bend between straight parts of the tubeĭBB (distance between bends) - this is a straight distance between bendsįor more complex components containing many bends in different planes, we can use the X,Y,Z coordinates of the tubes with the Center Line Radius (CLR) to simply define both the parameters used above, and the DBB for all bends. There is a practical demonstration of this calculation and their effect on your choice of tool in the Choice of Tools section. 'D' of bend = Central line radius CLR / Outer diameter of tube ODĭifficulty of bending depends on both parameters at the same time. rather than buckling whereas for Zone III normally an infinite radius die ( or a. This parameter determines the character of the bend and whether it is a bend on a large radius or a bend on a small radius. In selecting a fragmenting tube material to use in an energy absorber. 'D' of bend - or so-called relative bend radius. Relative wall thickness = wall thickness / external bend radius, however, it is really the same thing reversed. Note: In some literature on the subject there is the inverted ratio calculation: Wall Factor (WF) = the outside diameter OD / thickness of the walls WT. Generally we can say that tubes with a relative WT below 10 are considered to be strong walled (thick walled) and conversely with a relative WT higher than 40 are thin walled.

The resulting value then determines whether it is a thin-walled or a thick-walled tube. This is the relationship of the outside diameter and the thickness of the walls of the tubes. For radii larger than 1 1/2' set 105 is ideal, this set is also used to radius the edge of a sheet prior to a rolling operation. Outside flange on a radius bend can be formed in one stroke if springback is not too great. Wall Factor (WF) - the relative thickness of the wall. Form fitting radius die set 103 is used primarily for small radius bends on light ga. Using a variety of parameters, we can judge the difficulty of the bend and suggest the best set of tools for a given application.

Radius die tubing bend chart