Bulk Milling Options

BulkRemoval GCDs represent one or more general volumes that need to be removed from the stock to make a finished part. By default, aPriori assumes that the volume is removed by rough milling, and assigns one or more Bulk Milling operations for this purpose. To access these operations, navigate to the BulkRemoval:1 GCD in the Geometric Cost Drivers pane, right-click and select Edit Operation. The Operation Sequence Selection window appears, displaying a node representing the machine performing the bulk milling operations (for example, 3 Axis Mill or 5 Axis Mill). Click + to expand the node and you will see one or more Bulk Milling operations, representing one or more roughing passes each performed with a particular tool diameter.

To see and adjust parameters of a Bulk Milling Operation, right-click one of these Bulk Milling operations and select Process Setup Options. The Process Setup Options window appears and displays characteristics of the operation, including chosen tool series and size, volume removed, and engagement time.

The following options allow you to adjust bulk milling parameters:

• Request Percent Milled: percent of the volume to be allocated to the designated individual bulk milling operation. By default, aPriori calculates this based on the geometric characteristics of the part, as well on the number of different tool diameters selected for bulk milling operations. To override the default, use the following option:

o Override Percent Milled: enter a number between 0 and 100, inclusive.

• Material Removal Rate: rate at which material is removed during chipmaking. By default this is based on feed, speed, and volume to be removed (see Chipmaking Time for Bulk Milling). Use the following option to override the default:

o Override: enter a value in cubic millimeters.

• Requested Tool Diameter: diameter of the selected tool. Larger diameters can decrease engagement time—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: aPriori multiplies the value you enter 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.

• Radial Cut Depth: engagement length as a percentage of the tool diameter. Radial cut depth helps determine contact area and cut time. See Chipmaking Time for Bulk Milling. The default is 50% in aPriori starting point VPEs. Use the following option to override the default:

o User Override: enter a whole number between 0 and 100, inclusive.

• Axial Cut Depth: cut depth as a percentage of the tool diameter. Axial cut depth helps determine contact area and cut time. See Chipmaking Time for Bulk Milling. The default is 50% in aPriori starting point VPEs. Use the following option to override the default:

o User Override: enter a whole number between 0 and 100, inclusive.

• Dropoff Volume: (Bulk Milling only) volume removed by an alternative process such as Wire EDM rather than a rough milling process. (To access this option, by right-click the top-most Bulk Milling node in the Manufacturing Process pane and select Process Setup Options.)

This defaults to 0. If you override the default, be sure to manually assign Wire EDM to the wired surfaces in order to account for Wire EDM cycle times and costs.

Use this option to override the default:

o Dropoff Volume: enter a value in cubic millimeters.