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      <title>Trim Surface Angles</title>
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      <div class="title_topic4" id="xps10_pagetitle">Trim Surface Angles</div>
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      <div class="title_division">Description</div>
      <p class="para_division">This check will determine the max angle that a trimmed shape strikes the sheet metal. The check essentially reports the entry and exit angles the trimming shape makes with the metal. The  <a class="links" href="javascript:void(0)" onclick="top.openFile('dieengr/dfm_trim_wall_angles.html');return(false);">Trim Wall Angles</a> check analyzes the other locations.
      </p>
      <div class="title_division">Purpose</div>
      <p class="para_division">To ensure that the trimming operation is not at an angle that will cause trimming steels to fracture or dull prematurely.</p>
      <div class="title_division">Computational Method</div>
      <p class="para_division">For this check, the following two reference directions are computed.</p>
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            <p class="para_item">The surface tangent direction, which is a direction 90 to the surface normal and trimming curve tangent.</p>
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         <li>
            <p class="para_item">The zero reference direction, which is a direction 90 to the trimming direction and trimming curve tangent.</p>
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      <p class="para_division">These directions are shown below.</p>
      <p class="para_division"><img align="bottom" src="graphics/dfm_trim_surface_angles2.gif" border="0"></p>
      <p class="para_division">A true angle measurement is taken between the surface tangent, and zero reference directions at a sufficient number of points along the boundary of the trimming object. (Said another way, the angle between two planes is being computed. One plane is defined by the trimming curve tangent and the surface normal. The other plane is defined by the trimming curve tangent and the trimming direction.) Up and down angles are in reference to the zero reference direction. If the angle measured from the zero reference direction to the surface tangent direction is in the opposite direction of the trimming direction, we have an up angle. If the opposite is true, we have a down angle.</p>
      <p class="para_division">The picture below shows these measurements.</p>
      <p class="para_division"><img align="bottom" src="graphics/dfm_trim_surface_angles1.gif" border="0"></p>
      <p class="para_division">If the angle is up, a deviation occurs if it is greater than Up Angles[0] value(?).</p>
      <p class="para_division">If the angle is down, a deviation occurs if it is greater than Down Angles[0] value(?).</p>
      <p class="para_division">Given the above method, the below example shows how the trim surface angle varies as it is computed at various locations around a triangular trimming object that is being moved through non-planar faces.</p>
      <p class="para_division"><img align="bottom" src="graphics/dfm_trim_surface_angles_iso.gif" border="0"></p>
      <p class="para_division"><img align="bottom" src="graphics/dfm_trim_surface_angles_top.gif" border="0"></p>
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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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               <div class="para_note">
                  <p class="para_note_body">  If sharp corners exist within the trimming boundary, the Trim Surface Angle check may not give the max angle that a trimmed shape strikes the metal. This however is only an issue if one ignores the Trim Corners criteria. The Trim Corners check requires all trimming boundaries to be smooth or a non-conformance is reported.</p>
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      <div class="title_division">Cost penalty</div>
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            <th bgcolor="#c0c0c0" colspan="1" rowspan="1" valign="top">
               <p class="para_th">Deviation</p>
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            <th bgcolor="#c0c0c0" colspan="1" rowspan="1" valign="top">
               <p class="para_th">Complexity Result</p>
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            <th bgcolor="#c0c0c0" colspan="1" rowspan="1" valign="top">
               <p class="para_th">Added Cost</p>
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               <p class="para_th">Complexity Value</p>
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               <p class="para_td">&gt; Up Angles[0] to Up Angles[1] up or</p>
               <p class="para_td">&gt; Down Angles[0] to Down Angles[1] down</p>
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            <td bgcolor="#f4f4f4" colspan="1" rowspan="1" valign="top">
               <ul>
                  <li>
                     <p class="para_item">...</p>
                  </li>
               </ul>
            </td>
            <td bgcolor="#f4f4f4" colspan="1" rowspan="1" valign="top">
               <p class="para_td">$XXX</p>
            </td>
            <td bgcolor="#f4f4f4" colspan="1" rowspan="1" valign="top">
               <p class="para_td">X</p>
            </td>
         </tr>
         <tr valign="top">
            <td bgcolor="#f4f4f4" colspan="1" rowspan="1" valign="top">
               <p class="para_td">&gt; Up Angles[1] up or</p>
               <p class="para_td">&gt; Down Angles[1] down</p>
            </td>
            <td bgcolor="#f4f4f4" colspan="1" rowspan="1" valign="top">
               <ul>
                  <li>
                     <p class="para_item">...</p>
                  </li>
                  <li>
                     <p class="para_item">...</p>
                  </li>
                  <li>
                     <p class="para_item">...</p>
                  </li>
               </ul>
            </td>
            <td bgcolor="#f4f4f4" colspan="1" rowspan="1" valign="top">
               <p class="para_td">$XXX</p>
            </td>
            <td bgcolor="#f4f4f4" colspan="1" rowspan="1" valign="top">
               <p class="para_td">X</p>
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