Pocket GCD

A Pocket is a volumetric GCD surrounded by walls that represents material removed by rough milling. Pocket GCDs appear in the Geometric Cost Drivers pane under the Volume node.

Pocket GCDs are extracted only if the site variable pocketExtractionEnabled is present and set to true (the setting in starting point VPEs). If the site variable is not present or is set to false, more volume will be included in a BulkRemoval GCD.

Pocket Recognition

The features recognized as pockets include

• Volume with walls and a flat floor

o Walls can be angled with respect to the floor.

o Walls can be with or without fillets.

o There can be gaps in the wall provided that at least 75% of the pocket floor is closer to a wall than an opening.

• Volume with shared walls and walls that lie below other walls

• Volume with a curved floor that is sufficiently close to being flat (see below)

• Volume with walls and a cylindrical floor

• Volume with a stepped floor, provided the steps are formed only by fillets. Walls can be angled with respect to the floor

• Volume whose floor has an upward embossed feature, provided that the feature’s height is one of the following:

o Less than 20% of the height of the volume’s walls (in which case the feature is assumed to have no impact on roughing tool selection).

o More than 80% of the height of the volume’s walls (in which case the geometric property Inside Diameter accounts for the feature, which impacts roughing tool selection).

• Volume with small, non-parallel floor segments, provided each such segment is adjacent to a perpendicular wall

• Volumes with no floor (through pockets). Walls must be parallel to one another (no + or – draft).

Curved-bottom pockets are recognized provided they are sufficiently flat. A pocket bottom is considered sufficiently flat if, roughly speaking, its depth-to-width ratio is less that the value of the site variable maxCurvedFloorPocketWidthDepthRatio (0.1 in starting point VPEs). Here, width is the SER width of the bottom surface, and depth is the maximum distance from the surface to its best-fit plane.

Volumes that are not currently recognized as pockets include:

• Open-sided volumes

• Volumes with islands

• Volumes with internal walls

• Through volumes with angled walls

Pocket Examples

The illustration below shows three volumes:

• The square volume (shown in purple) with a flat floor and fillets (one is shown in yellow) is recognized as a pocket.

• The elliptical through volume (shown in purple) is recognized as a pocket (walls of a through pocket must be parallel).

• The circular volume is not recognized as a pocket, but rather is identified as a simple hole.

The following illustration shows a pocket (in purple) with a cylindrical floor.

The purple volume in the image below is one of four identical through pockets. The walls must be parallel for a through pocket to be recognized.

The lower volume (in purple) shown below is recognized as a pocket, while the upper volume is not recognized as pocket because it is open sided. These two volumes together are not considered a single pocket, since there would be a step in the floor that is not formed solely by a fillet.

Pocket Properties and Relations

Pocket properties include the following:

• Floor Type: values include THROUGH, FLAT, CYLINDRICAL, CURVED, MULTI, and OTHER.

• Wall Type: values include PARALLEL and OTHER.

• Direction: specifies how direction-dependent properties (depth, corner diameter, and inside diameter tool volume) are computed. Values include PRISMATIC, RADIAL, and OTHER. For a PRISMATIC pocket, Depth is measured along a setup axis (either parallel to the walls or normal to the floor); for a RADIAL pocket, Depth is measured along a radius of the cylindrical floor. If the Direction is Other, Depth is not computed.

• Depth

• Volume

• Corner Diameter

• Inside Tool Diameter: specifies the maximum tool diameter that can access at least 80% of the pocket volume.

• Inside Diameter Tool Volume: specifies the volume accessed by a tool whose diameter is Inside Tool Diameter.

Pocket relations include the following:

• Is Wall Of

• Is Floor Of

• Is Fillet Of

• Is Accessible From

These properties and relations affect tool selection and cut time calculations—see Diameter Selection for Pocket Roughing, Tool Type Selection for Pocket Rough Milling, Chipmaking Time for Pocket Rough Milling, and Pocket Rough Milling Options.