Surface Finishing Milling Options

aPriori supports a variety of surface finishing operations that can be applied to the different types of surface GCDs, depending on the capabilities of the machining process used. For example, Facing may be applied to PlanarFace GCDs; Side Milling may be applied to PlanarFace and CurvedWall GCDs; Contouring may be applied to PlanarFace, CurvedWall, and CurvedSurface GCDs.

You can specify options for how surface finishing operations are performed on specific GCDs by locating the specific surface finishing operation node of interest in the Manufacturing Process Pane, then locating the relevant surface GCD under it. Right click the GCD to invoke the Process Options editor.

See Working with Features to Review and Working with the Heat Map for more information on the use of the options listed in this section.

The following options are available (not all operations support all these options):

• Number of Finishing Passes: number of times the tool passes over the entire surface. Chipmaking time increases as the number of passes goes up--see Chipmaking Time for Surface Finishing Milling Operations.

Select one of the following options:

o Computed Number of Finishing Passes: aPriori determines this based on the required tolerance and the lookup table tblGtolProcessCapabilities. This typically defaults to 1 in aPriori starting point VPEs.

o Override Number of Finishing Passes: enter a value greater than or equal to 1.

• Requested Tool Diameter: diameter of the selected tool. Larger diameters can decrease engagement time (assuming sufficient spindle power)—see Operation Cycle Time and Cut Time Calculations--and have a more favorable length-to-diameter ratio. Smaller diameters have better corner accessibility.

Select one of the following options:

o Use Computed Tool Diameter: aPriori chooses a tool diameter based on a number of factors, including overall part size, accessibility of the GCD’s corners (if any), and the values of setup options that constrain tool size. See Tool Selection for more information.

o Override Tool Diameter: enter the tool diameter in millimeters.

• Requested Tool Cutting Speed: how fast the tool turns in unit distance per unit time; that is, the speed at which a point on the outer edge of the tool moves along the circular path around the center of the tool. This value is used (along with feed, tool diameter, and cutting width) to determine area removal rate. See Operation Cycle Time and Cut Time Calculations for more information on how speed contributes to cutting time.

Select one of the following options:

o Use Recommended Tool Cutting Speed: aPriori determines this value by interpolation from data tables based on tool series, tool diameter, and material cut code--see Tool Selection. This value is adjusted to compensate for various factors, including machine spindle speed limitations and stock hardness. The value is also adjusted by multiplying by the cost model variable millSpeedAdjustment. The adjusted value is used to help determine area removal rate.

o Override Tool Cutting Speed: enter a speed in meters per minute. This value is adjusted to compensate for various factors, including machine spindle speed limitations and stock hardness. The value is also adjusted by multiplying by the cost model variable millSpeedAdjustment. The adjusted value is used to help determine area removal rate.

• Requested Feed per Tooth: distance the tool travels along the surface of the part per tooth of the tool during one rotation. The number of tool teeth times this value is the distance the tool travels along the surface of the part per rotation of the tool. This value is used (along with speed, tool diameter and cutting width) to determine area removal rate. See Operation Cycle Time and Cut Time Calculations for more information on how feed contributes to cutting time.

Select one of the following options:

o Use Computed Feed per Tooth: aPriori determines this value by interpolation from data tables based on tool series, tool diameter, and material cut code—see Tool Selection. aPriori multiplies this value by the number of teeth to derive tool feed. This value is adjusted to compensate for various factors, including tool reach and required tolerance. Tool feed is also adjusted by multiplying by the cost model variable millFeedAdjustment. The adjusted value is used to help determine area removal rate.

o User Override: enter a value in millimeters. aPriori multiplies this value by the number of teeth to derive tool feed. This value is adjusted to compensate for various factors, including tool reach and required tolerance. Tool feed is also adjusted by multiplying by the cost model variable millFeedAdjustment. The adjusted value is used to help determine area removal rate.

• Number of Teeth: number of tool teeth. This value together with feed per tooth determines feed (which affects area removal rate)—see Operation Cycle Time and Cut Time Calculations.

Select one of the following options:

o Number of teeth: aPriori determines this value by interpolation from data tables based on tool series, tool diameter, and material cut code—see Tool Selection. aPriori multiplies this value by the feed per tooth to derive tool feed. This value is adjusted to compensate for various factors, including tool reach and required tolerance. Tool feed is also adjusted by multiplying by the cost model variable millFeedAdjustment. The adjusted value is used to help determine area removal rate.

o User Override: enter a value greater than or equal to 2.

If you supply a user override for both Number of Teeth and Requested Feed per Tooth, aPriori multiplies the two values together to derive tool feed.

If you supply a user override for Number of Teeth, and you do not specify a user override for Requested Feed per Tooth, aPriori sets the unadjusted value for feed as follows:

Feed = Interpolated Feed * (Specified Number of Teeth / Interpolated Number of Teeth)

(Interpolated feed and interpolated number of teeth are derived from data tables during tool selection—see Tool Selection.)

In either case, the value is adjusted to compensate for various factors, including tool reach and required tolerance. Tool feed is also adjusted by multiplying by the cost model variable millFeedAdjustment. The adjusted value is used to help determine area removal rate.

• Contouring Tool Stepover: separation between ball-end mill pass steps, that is, the distance between the tool centerline during successive finishing passes.

Select one of the following options:

o Use Computed Stepover: value computed by aPriori based on tool diameter and GCD roughness, as well on the cost model variable passStepSafetyFactor (which defaults to 1--the stepover decreases as passStepSafetyFactor increases).

o Override Stepover : enter a value that does not exceed the tool diameter