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      <title>Hole to Wall</title>
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      <div class="title_topic4" id="xps10_pagetitle">Hole to Wall</div>
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      <div class="title_division">Description</div>
      <p class="para_division">To measure the distance from the punch stripper or button to the nearest walls above and below the pierce shape. This check also measures a minimum flat area around the pierce shape.</p>
      <div class="title_division">Purpose</div>
      <p class="para_division">The purpose of this check is to ensure that a hole is not too close to a wall for using standard pierce equipment for manufacturing, and that there is sufficient bearing surface around the pierce shape to avoid hole distortion.</p>
      <div class="title_division">Computational Method</div>
      <p class="para_division">Both the checks listed below are performed for each hole. As with all criteria checks, the goal is to provide as much information as possible concerning nonconformances.</p>
      <div class="title_division">Measuring Flatness</div>
      <p class="para_division">For this check, a mid-plane is computed for the hole that is being pierced. This mid-plane is computed by first finding a centroid of all the sample points on the pierce object edge(s). Then planes are computed using the centroid and two neighboring sample points. The normals from these planes is averaged to establish the direction of the mid-plane. The location point of the mid-plane will be half way between the extreme upper and extreme lower sample points.</p>
      <p class="para_division">If the offset pierce shape deviates too much from this plane, then a nonconformance is recorded. To perform this check the shape of the hole on the sheet is sampled. These points are then offset Hole Flat Distance value(?) normal to the piercing direction, and then projected back to the sheet. The distance of these projected points to the mid-plane must be less than Hole Flat Tolerance value(?) to pass this check. The picture below illustrates this check.</p>
      <p align="center"><img align="bottom" src="graphics/dfm_hole_to_wall_flatness.gif"></p>
      <p class="para_division">The location where the maximum deviation occurs is provided as feedback. The distance is displayed from the sheet to the mid-plane. A dashed line is displayed to the corresponding sample point of the hole on the sheet. This is shown below.</p>
      <p align="center"><img align="bottom" src="graphics/dfm_hole_to_wall_flat_check.gif"></p>
      <div class="title_division">Measuring Shank to Wall Clearance</div>
      <p class="para_division">An actual distance between the shank and the nearest wall is not computed. Rather solid cylinders are constructed and then a check is made to see if these cylinders intersect above or below the sheet. The length of each cylinder is Cylinder Length value(?) . Each cylinder is constructed along the piercing direction starting at a distance of Wall Tolerance value(?) above and below (thickness added) the mid-plane used from the flatness check. The picture below illustrates this.</p>
      <p align="center"><img align="bottom" src="graphics/dfm_hole_to_wall_above_below.gif"></p>
      <p class="para_division">The shank size used for this check is obtained from the Pierce Common Shank Size Table found in the  <a class="links" href="javascript:void(0)" onclick="top.openFile('dieengr/dfm_pierce_commonization.html');return(false);">Pierce Commonization </a>criteria. If the shank is smaller than the hole size, then the bigger hole size will be used for the distance checking.
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      <div class="title_division">Cost Penalty</div>
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               <p class="para_th">Deviation</p>
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               <p class="para_th">Complexity Result</p>
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               <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">Less than Standard Shank to Wall to Deviation Shank to Wall</p>
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                     <p class="para_item">...</p>
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                  <li>
                     <p class="para_item">...</p>
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               <p class="para_td">$XXX</p>
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            <td bgcolor="#f4f4f4" colspan="1" rowspan="1" valign="middle">
               <p class="para_td">X</p>
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               <p class="para_td">Less than Deviation Shank to Wall</p>
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            <td bgcolor="#f4f4f4" colspan="1" rowspan="1" valign="middle">
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                  <li>
                     <p class="para_item">...</p>
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                  <li>
                     <p class="para_item">...</p>
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            <td bgcolor="#f4f4f4" colspan="1" rowspan="1" valign="middle">
               <p class="para_td">$XXX</p>
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            <td bgcolor="#f4f4f4" colspan="1" rowspan="1" valign="middle">
               <p class="para_td">X</p>
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               <p class="para_td">Less than Hole Flat Distance</p>
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               <p class="para_td">$XXX</p>
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            <td bgcolor="#f4f4f4" colspan="1" rowspan="1" valign="middle">
               <p class="para_td">X</p>
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