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      <title>Machinable Regions &mdash; per Cut Level</title>
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      <div class="title_topic2" id="xps10_pagetitle">Machinable Regions &mdash; per Cut Level</div>
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      <p class="para_topic">Machinable Regions are the areas at each cut level where the tool can cut without gouging the part. The tool will only be positioned into those areas where it can remove material and not gouge the part. When a cut level has islands or walls that are close enough together to prevent the tool to cut through without gouging, the area is divided into separate regions. The following figure shows how an area is broken up in to multiple cut regions because the tool is too large to fit in some areas without gouging.</p>
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         <p align="center"><img align="bottom" src="graphics/pcmill_intfi08.gif"></p>
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      <div class="title_figure">Machinable Regions</div>
      <p class="para_topic">The system creates machinable regions by tracing around the Part and Blank geometry. These traces are made at each cut level to create one or more machinable regions per level. Each region consists of an enclosed peripheral shape and may contain islands inside. Islands that are outside the enclosed peripheral shape will not be part of the machinable region and will form separate Open Regions.</p>
      <p class="para_topic">If Blank geometry is defined, the processor will cut only the regions which lie within the blank and ignore any cavity regions which lie outside the blank as illustrated below.</p>
      <div class="figure">
         <p align="center"><img align="bottom" src="graphics/pcmill_intfi07.gif"></p>
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      <div class="title_figure">Only Regions Within the Blank are Cut</div>
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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"> NOTE: Using the edges of Part geometry to define Blank geometry may cause the processor to fail during the boolean of the Part and Blank shapes. This is especially true if the members are not simple curves such as lines and arcs. To avoid this problem (and because the Blank geometry does not have a tied tolerance), the traces of the Blank geometry are adjusted by 10x the average Tolerance. This assures that if there is overlap between Part and Blank shape, the boolean will have a high rate of success.</p>
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      <p class="para_topic">A Closed region is created when the tracings create a closed peripheral shape around material to be removed. Islands may exist within the peripheral shape. The following are different types of Closed regions.</p>
      <p class="para_topic">A Facing region is a type of Closed region where Blank geometry creates the periphery of the bounded area and and no Part geometry falls within that bounded area. The tool will remove all Blank material from that level.</p>
      <div class="figure">
         <p align="center"><img align="bottom" src="graphics/pcmill_intfi16.gif"></p>
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      <div class="title_figure">Facing Region</div>
      <p class="para_topic">A Core region is a type of Closed region where the Blank geometry creates the periphery of the bounded area and Part geometry falls within that bounded area. The tool will remove the Blank material from around the Part geometry.</p>
      <div class="figure">
         <p align="center"><img align="bottom" src="graphics/pcmill_intfi15.gif"></p>
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      <div class="title_figure">Core Region</div>
      <p class="para_topic">A Cavity region is a type of Closed region where the Part geometry creates a peripheral boundary. This type of region may contain islands. The tool will remove the material from within the cavity to the Part geometry.</p>
      <div class="figure">
         <p align="center"><img align="bottom" src="graphics/pcmill_intfi06.gif"></p>
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      <div class="title_figure">Cavity Region</div>
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            <td valign="top" align="left"><img align="left" src="../graphics/warning.gif" alt="Warning" title="Warning"></td>
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               <div class="para_warning">
                  <p class="para_warning_body">  CAUTION: Because Cavity Milling operations cannot extend faces beyond their edges, it is important while machining core regions that the Blank geometry and Part geometry create closed regions at each cut level to accurately define where the material is to be removed.</p>
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      <p class="para_topic">An Open Sided region is a type of Closed region where the Part Geometry and the Blank Geometry form a peripheral loop containing segments that are defined by both the Part and Blank. The segments defined by Part geometry cannot be violated. The segments defined by Blank geometry form the open side of the cut region and allow the tool to pass through as illustrated below.</p>
      <div class="figure">
         <p align="center"><img align="bottom" src="graphics/pcmill_intfi14.gif"></p>
      </div>
      <div class="title_figure">Open Sided Region</div>
      <p class="para_topic">An Open region is created when the tracings do not create a closed peripheral shape around material to be removed. This can occur when the Part geometry consists of islands only with with no Blank geometry enclosing them, or when the Part geometry does not form an enclosed area (as with an open Part boundary) as illustrated below.</p>
      <p class="para_topic">Open regions can only use Profile or Standard cut types. Attempting to use any other cut type will cause the system to display an error message and will fail to generate a tool path.</p>
      <div class="figure">
         <p align="center"><img align="bottom" src="graphics/pcmill_intfi05.gif"></p>
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      <div class="title_figure">Open Regions</div>
      <p class="para_topic">Do not confuse a Core Region (which is a type of Closed Region) with an Open Region containing islands. Notice in the following illustration that the Core Region is defined by both Part geometry and Blank geometry. The Open Region, however, is defined only by the Part geometry which forms an island. No Blank geometry is defined in the Open region.</p>
      <div class="figure">
         <p align="center"><img align="bottom" src="graphics/pcmill_intfi04.gif"></p>
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      <div class="title_figure">Core Region vs. Open Region</div>
      <div class="figure">
         <p align="center"><img align="bottom" src="graphics/pcmill_intfi03.gif"></p>
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      <div class="title_figure">Open Sided Region vs. Open Region</div>
      <p class="para_topic">In each of the above two examples, the Open Region is a shape or collection of shapes that do not represent a continuous area.</p>
      <p class="para_topic">During tool path generation for a Planar Milling operation when the tool axis is normal to the Part Surface, the tool axis is defined relative to the normal of the Floor and the Machine Coordinate System (MCS) as follows:</p>
      <ul>
         <li>
            <p class="para_item">If the Z-axis of the MCS is perpendicular to the normal of the floor, then the tool axis is the normal of the floor.</p>
         </li>
         <li>
            <p class="para_item">If the Z-axis of the MCS is not perpendicular to the normal of the floor, the tool axis is the normal of the floor that is most nearly aligned with the Z-axis of the MCS.</p>
         </li>
      </ul>
      <p class="para_topic">When there is more than one area at a cut level to be machined, you have two methods of ordering how these areas will be cut as they are propagated to successive cut levels.</p>
      <ul>
         <li>
            <p class="para_item">Remove all of the machinable regions at one cut level before moving to the next cut level (cut by level first).</p>
         </li>
         <li>
            <p class="para_item">Remove each cut region to its lowest cut level before moving to the next cut</p>
         </li>
      </ul>
      <p class="para_topic">If an undefined region includes all island shapes, these shapes will always be cut by level first regardless of user-defined cut order.</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">With the Follow Periphery pattern, some narrow regions may not be cut, and may leave excess material for the next cut level. For this reason, wall cleanup and island cleanup should both be turned on in the cutting parameters. These assure that the cutter takes a pass along each part and island wall, and does not leave any excess material.</p>
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               <div class="para_note">
                  <p class="para_note_body">Wall Cleanup should be turned on when using the Follow Periphery, Zig, and Zig-Zag cut patterns. This assures that excess material will not be left along the wall of the part, which could leave too much material for the tool at the next cut level.</p>
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      <table border="0">
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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">Island Cleanup should be turned on when using the follow periphery cut pattern. This assures that excess material will not be left along the wall of islands, which could leave too much material for the tool at the next cut level.</p>
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