Add or edit a sheet metal unfold rule

Named sheet metal unfold rules allow the definition of three types of unfold methods:

1. linear approximation
2. specified bend table
3. custom equation

Uniquely named unfolding rules are associated with uniquely named sheet metal rules to define the default modeling behavior for various materials and manufacturing conditions.

Create and name a new sheet metal unfold rule:

Creating a sheet metal unfold rule involves copying a supplied Default rule (or another previously created rule) and making and saving changes to the KFactor, bend table values or custom equation definitions.

1. Click Manage tab Styles and Standards panel Styles Editor to open the Style and Standard Editor dialog box.
2. Click the expand/collapse “+” to the left of the Sheet Metal Unfold Rule entry in the left-hand portion of the Style and Standard Editor dialog box to display the list of existing unfold rules.
3. Click the Default rule to serve as the template for the rule you create.
4. Click New along the top of the right-hand portion of the Style and Standard Editor dialog box.
5. The New Style Name dialog box appears so you can name the new sheet metal unfold rule you are about to create. Enter a descriptive name to replace the supplied Copy of Default in the Name field and click OK.
6. The New Style Name dialog is dismissed and a new sheet metal unfold rule is listed. The new rule is an exact copy of the Default rule and you make edits as described in the following sections before your new unfold rule definition is completed and saved.

Note: If there are already sheet metal unfold rules defined in your file or library you can select any rule to serve as the basis for your new unfold rule.

Select and edit the sheet metal unfold method:

Select one of three methods to transform the folded model to a flattened state:

	1. Using a linear approximation (KFactor) Using the Linear unfolding method, sheet metal parts unfold using a KFactor value that is uniformly applied to all bend angles. Select fx Linear as the Unfold Method. Optionally enter an alternative KFactor value in the KFactor Value field. Optionally enter an alternative Spline Factor value in the Spline Factor Value field. Note - this value defaults to 0.5 and affects the flattened sizes of Contour Flanges, Contour Rolls or Lofted Flanges with elliptical or spline segments within the feature profile (as well as the length of any non-cylindrical or conical bend). Adjust the value up or down to more closely represent your manufacturing requirements.
	2. Using a bend table Using the Bend Table unfolding method, sheet metal parts unfold using empirical values that are measured or derived and applied to specific bend angles within the table. Values for angles not defined within the table are calculated using a Backup KFactor. Select Bend Table as the Unfold Method. Notice that the right-hand portion of the dialog box updates to provide an integrated environment for editing a sheet metal bend table. Optionally select alternative Linear Units from the dropdown list. Optionally select the Outer or Open angle radio button to define how angles are measured. Optionally select an existing Thickness or add a new Thickness. Optionally alter the Backup KFactor value to something more appropriate to your requirements from what is displayed. Optionally enter an alternative Spline Factor value in the Spline Factor Value field. Note - this value defaults to 0.5 and affects the flattened sizes of Contour Flanges, Contour Rolls or Lofted Flanges with elliptical or spline segments within the feature profile (as well as the length of any non-cylindrical or conical bend). Adjust the value up or down to more closely represent your manufacturing requirements. Optionally alter the Table Tolerance values to something more appropriate to your requirements from what is displayed for: Sheet, Min/Max Radii and/or Min/Max Angle. Optionally add rows for unspecified angle values. Optionally add columns for unspecified bend radii. Optionally edit individual table cells as required based upon measured results for specific material thicknesses, angles, radii, and shop equipment. Additional details on editing bend tables can be found in the Create bend tables for sheet metal materials topic.
	3. Using a custom equation Using the Custom Equation unfolding method, sheet metal parts unfold using equations that solve for bend compensation, bend deduction, bend allowance or KFactor using supplied and derived variables. Values for angles not defined within bounding conditions are calculated using a Backup KFactor. Select Custom Equation as the Unfold Method. Notice that the right-hand portion of the dialog box updates to provide an integrated environment for editing custom unfold equations. Optionally select an alternative Equation Type from the dropdown list. Optionally select Bending Angle or Open Angle from the Angular Reference dropdown list. Optionally select a displayed equation cell to edit the equation (double-click the cell or RMB and select Edit from the context menu to open the edit dialog). Optionally select a displayed bounding condition to modify the defined bounding range (double-click the cell or RMB and select Edit from the context menu to open the edit dialog). Optionally add rows containing equations for unspecified bounding conditions. Optionally delete un-needed rows. Optionally edit the Backup KFactor Value that will be applied if angular values are encountered that are not covered by the specified bounding conditions. Optionally enter an alternative Spline Factor value in the Spline Factor Value field. Note - this value defaults to 0.5 and affects the flattened sizes of Contour Flanges, Contour Rolls or Lofted Flanges with elliptical or spline segments within the feature profile (as well as the length of any non-cylindrical or conical bend). Adjust the value up or down to more closely represent your manufacturing requirements. Equation descriptions and equation editing details can be found in the Custom Unfold Equations topic.

Save sheet metal unfold rule edits:

Once any selection or value is altered from the unfold rule copied two additional commands are enabled along the top of the right-hand portion of the Style and Standard Editor dialog box.

• Click Save to save all of the changes you have made to the newly created sheet metal rule.

Note: To discard any changes that you have made and start over using the settings originally copied click Reset and return to the previous Step 7 to begin again.

Edit a sheet metal unfold rule

The procedure for editing a sheet metal unfold rule is the same as for the creation of a new sheet metal rule as described previously with the omission of steps 4 and 5 where a copy of an existing rule is made and given a new name.

1. Click the expand/collapse “+” to the left of the Sheet Metal Unfold Rule entry in the left-hand portion of the Style and Standard Editor dialog box to display the list of existing rules.
2. Click the rule to edit.
3. Make the needed changes to the KFactor used for a linear unfold or to the bend table values needed.
4. Click Save to save all of the changes to the selected sheet metal rule.