11/11/13Fabrication Formulas | SheetMetal.Me SheetMetal.Me & BendAllowance.Com Sheet Metal Fabrication Resources, Blog and Discussion Forum Pages Home Fabrication Formulas Tooling Terminology Design Guidelines Sheet Metal Gauge Chart Search for: Advertisements Search Fabrication Formulas Formulas: Bend Allowance (BA) - The amount of added to the sum of the two leg lengths to obtain the flat pattern length. Bend Deduction (BD) - The amount removed from the sum of the two flange lengths to obtain a flat pattern. sheetmetal.me/formulas-and-functions/ 1/4 11/11/13 Fabrication Formulas | SheetMetal.A line that runs parallel to the inside of the workpiece.A constant based off of the K-Factor used by Pro-Engineer in place of a K-Factor.Distance between the inside mold lines and the bend line.The measurement from the surface of the outside radius to the apex of the outside mold lines.me/formulas-and-functions/ 2/4 .The ratio of the position of the Neutral Axis to the Material Thickness.Me Material Thickness (MT) . Inside Through the Material (ISTM) . Y-Factor (Y) .The final formed inside radius after spring back has occurred.Distance between the outside tangent points and the apex of the outside mold lines.A line that runs parallel to the outside of the workpiece. Outside Setback (OSSB) .The inside angle between the two legs or flanges of a bend. K-Factor (K) . Outside Offset (OSOS) . Inside Offset (ISOS) . Inside Mold Line (IML) .Distance between the inside tangent points and the apex of the inside mold lines. Outside Mold Line (OML) . Bend Angle (B<) . Inside Setback (ISSB) . Outside Radius (OR) .The distance between the outside and inside mold lines. Inside Radius (IR) .The gauge of the material in decimal form. sheetmetal.The final formed outside radius after spring back has occurred. When calculating the outside offset use the included bend angle. Annealing .In order to prevent rust steel is dipped into molten zinc which alloys itself with the surface of the steel. Bump Bending . done typically with lasers. Box Bending . Gage.Light bends added to sheet metal in order to stiffen its surface. Foil .The deflection along a bend due to the tooling or brake not being able to apply equal tonnage along the bend.The process of cutting flat patterns from stock sheeting. Bottom Bending . Galvanized .The thickness of the metal organized by numbers. Bend Line Shift (BLS) . Gusset . Bending . Crowning is controlled on modern brakes with internal hydraulic systems which can help equalize pressure.Also known as Step Bending. Crowning . This is used to calculate the back stop location when working off of a flat pattern. water jets. Galvanneal . Terminology Air Bending .One of the three types of bending for sheet metal where the punch penetrates into the sheet metal under high tonnage forming a consistent bend.Annealing is a treatment for metals where a material is heated above the recrystallization temperature maintained for a period of time and then cooled. plasmas or punch presses. the smaller the number the thinner the metal. relieve internal stresses and improve its cold working prope rties.Steel which has been galvanized and then subsequently annealed.The length of the workpiece when measured from the apex to the edge of the bend.Distance between the outside mold lines and the bend line. Annealing is used to soften material. Bend Line .Me Inside Shift (ISS) . flattened. but rather forced into the bend in order to stiffen the piece. Air Bend Force Chart . Flat Pattern . Blanking .One of the three types of bending for sheet metal where the radius of the punch tip is pushed into the sheet metal.One of the three types of bending for sheet metal where the outside mold line is not pressed against the die.11/11/13 Fabrication Formulas | SheetMetal. This forms a safe edge for handling and stiffens the part’s edge.me/formulas-and-functions/ 3/4 .Very thin sheet metal made from typically malleable metals such as aluminum and gold. Curling . tooling and length.The line across the metal where the punch comes in contact with the metal and the bend begins. closed loop at the end of the sheet.A forming process which leaves a circular.The general term for the unfolded. Gauge . the process for forming a large radius with conventional tooling by performing a series bends in close proximity.The process of cold working metal to achieve a desired profile.A section of the metal inside a bend which is not bent.A chart used to calculate the tonnage required for a bend based on thickness. sheetmetal. geometry of a part.The process of bending a 4 sided sheet metal box. Cross Break . Flange Length . Coining .The distance from the Outside Mold Line to the original bend line on the flat pattern. Hems can be flattened. Reflex Angle . Tolerances .The amount to which the workpiece resists bending by returning to its original shape. punches and holders found on press brake equipment. but opposite direction. R Bending . Work Piece . Step Bending .me/formulas-and-functions/ 4/4 . are used to create a ‘z’ shaped profile.Bending with an inside radius greater than 8 times the material thickness. Straight Angle .When the radius of the bend is less than %63 of the material thickness. Obtuse Angle .Also known as an offset bend.General dimensioning and tolerances of bends and sheet metal.The general term for the sheet metal part being bent. Kink .Also known as R Bending. SheetMetal. left open or in a variety of tear drop shapes. Leg . Large Radius Bending .General term for the dies. large radius bending is when the inside radius is greater than 8 times the material thickness. Tooling .Me 2010. Spring Back . this is when two bends of the same angle.A flange that reaches 180° or more.Also known as bump bending.Length of the workpiece from the edge to the outside tangent point of the bend radius.A geometry term for an angle which is greater than 90°. seen commonly with hemming applications. Neutral Axis .A light bend typically between 5° and 15° which is used to stiffen a flat piece of metal. Jog . sheetmetal.An imaginary line within the bend where the material goes through no compression or stretching during the bend process. the process for forming a large radius with conventional tooling by performing a series bends in close proximity.A geometry term for an angle which is equal to 180°.11/11/13 Fabrication Formulas | SheetMetal.Me Hem .A geometry term for an angle which is greater than 180° Sharp Bend .