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      <div class="title_topic4" id="xps10_pagetitle">Flange Tips and techniques</div>
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      <div class="title_division">Parameters</div>
      <p class="para_division">The two methods to determine the length of the flange are <b class="uiTerm">Tangent</b> and <b class="uiTerm">Contour</b>. The tangent length is the length of the web of the <b class="uiTerm">Flange</b> feature. The contour length is measured from the intersection of a plane extended from the outside face of the feature the attached flange and a plane extending from the outside of the web to the bottom of the web.
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      <p class="para_division">If you define the length of the flange using <b class="uiTerm">Contour</b> then the flange's angle cannot be 180&deg; as the theoretical intersection becomes infinite.
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      <p class="para_division">When applying a taper to the side of the flange a positive number tapers into the flange, or removes material, and a negative number tapers away from the flange, or adds material.</p>
      <p class="para_division">Do not change the width of the bend face of a flange by adding a feature, such as an extrude to the face. If you do this you will not be able to get a bend center line or bend tangent lines created in a flat pattern by the flange. The best way to widen the bend face would be to create the flange too wide and use a <b class="uiTerm">Cutout</b> to trim the flange to the proper width.
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      <div class="title_division">Adjacent face</div>
      <p class="para_division">You must select an edge when you are constructing the flange. The edge you are allowed to select the must be linear and attached to two planar faces. The edge you select will determine the bend direction. The software will select a planar face to attach the flange. If the planar face that highlights is the wrong face, simply select the <b class="uiTerm">Adjacent Face</b> button and the system will select the other planar face.
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      <div class="title_division">Positioning</div>
      <p class="para_division">The <b class="uiTerm">Flange</b> feature can introduce large changes to a part because you can modify the bend angle using the <b class="uiTerm">Form/Unform</b> button. It is important that all flanges be fully constrained. Both under and over constrained flanges can fail to position properly. In these cases, you can choose to <b class="uiTerm">Undo</b> the operation or suppress the flange.
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      <p class="para_division">The flange allows the use of expressions to determine its width and thickness. If you do this you must position the flange using RPOs. You may use any valid RPO method, but the flange must be totally <b class="uiTerm">Positional Constrained</b>.
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      <p class="para_division">When you change the <b class="uiTerm">Width</b> option from <b class="uiTerm">Infer from Edge</b> to <b class="uiTerm">Use Expression</b> you must completely constrain the flange. If you do not totally constrain an attached flange to a block you might not encounter a problem. If you place a flange on another flange and do not totally constrain this flange, problems will occur when you <b class="uiTerm">Form/Unform</b> the flanges. The flange that is attached to the first flange will not be able to follow is <b class="uiTerm">Parent</b>, the flange, during a <b class="uiTerm">Form/Unform</b>.
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      <div class="title_division">Reference lines</div>
      <p class="para_division">There is an option to create <b class="uiTerm">Contour</b>, <b class="uiTerm">Mold</b>, and <b class="uiTerm">Form Block</b> lines. You can use these lines on a drawing for dimensioning or they can be passed to the <b class="uiTerm">Flat Pattern</b>.
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      <div class="title_division">Features on flanges</div>
      <p class="para_division">Any feature that you apply to a flange should be positioned directly to the flange geometry and not to other geometry in the part. Note that after flattening, the bend area is no longer cylindrical but planar. Datum axes created through the axis of a flange cylinder fail to position properly.</p>
      <p class="para_division">The only type of features that you can place on the cylindrical bend area of a flange feature is a Sheet Metal feature such as the <b class="uiTerm">Hole</b>, <b class="uiTerm">Slot</b>, <b class="uiTerm">Cutout</b>, etc. Any other feature, including instance sets, which is placed on the bend, will give unpredictable results during forming and unforming. Instead, convert the feature or instance set to its equivalent sheet metal feature.
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      <div class="title_division">Instance/Mirror</div>
      <p class="para_division">The <b class="uiTerm">Flange</b> feature maybe Instanced, but with a limitation. The instanced/mirrored flange will not be formed/unformed by itself; it will only form/unform when its parent forms/unforms. This might cause a problem if the manufacturing process calls for one flange to be form before the other. If the manufacturing process calls for both flanges to form at the same time then the mirroring of the flange will work fine. The figure below is an example of a part where you formed all of the flanges at the same time when manufactured.
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      <p align="center"><img align="bottom" src="graphics/image38.gif"></p>
      <p class="para_division">The figure below shows a model that the instancing of the flanges may not work, because to illustrate the manufacturing process requires the flanges to unform independently of each other.</p>
      <p align="center"><img align="bottom" src="graphics/image398.gif"></p>
      <div class="title_division">Self&ndash;forming features</div>
      <p class="para_division">There are two unforming methods available for Sheet Metal Features. If you have <b class="uiTerm">Preferences&rarr;Sheet Metal&rarr;Use Self&ndash;Forming Features</b> enabled, then all newly created flanges will have the ability to unform themselves using the <b class="uiTerm">Form/Unform</b> dialog box. When <b class="uiTerm">Preferences&rarr;Sheet Metal&rarr;Use Forming Operations</b> is enabled, you must unform using the <b class="uiTerm">Unbend</b> and <b class="uiTerm">Rebend</b> features.
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            <td valign="top" align="left"><img align="left" src="../graphics/note.gif" alt="Note" title="Note"></td>
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                  <p class="para_note_body">You may apply the <b class="uiTerm">Unbend/Rebend</b> feature to a self&ndash;forming flange, however, it will loose its ability to form and unform. You can revert flange back into a self&ndash;forming feature if you delete the Unbend feature and use the <b class="uiTerm">Part Navigator&rarr;Make Self&ndash;Forming Feature</b>.
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