Breakoff Formulas
Cycle Time = Process Time * Adjustment Factor
Cycle time is the product of the following:
• Process time: this is the sum of the process times for each support structure (see formula).
• Adjustment factor (specified by the cost model variable cycleTimeAdjustmentFactor). This factor is 1 in aPriori starting point VPEs. VPE administrators can modify cycleTimeAdjustmentFactor in order to adjust cycle times across processes within the current VPE.
Process Time per Support Structure = Positioning Time + Removal Time
Process time per structure is the sum of the following:
• Positioning time: this is the time spent positioning the tool prior to breaking off the top of the support structure, plus the time spent positioning the tool priori to breaking off the bottom of the support structure (except for DMLS supports that are connected to the base plate—this connection is severed by a separate, base-removal process).
Each time is specified by the cost model variable handBreakoffPositioningTime (3 seconds in starting point VPEs). So, except for DMLS supports connected to the base plate, the positioning time per support structure is twice the value of the cost model variable. For DMLS supports connected to the base plate, the positioning time per support structure is equal to the value of the cost model variable.
• Removal time: depends on the area of contact between the support structure and the part or build plate (see formula).
Removal Time = Support Contact Area / Hand Breakoff Rate
Removal time depends on the following:
• Hand breakoff rate: area per unit time, looked up by process (DMLS, Material Jetting, Stereolithography) in the lookup table tblHandBreakoffRate.
If the lookup fails, the breakoff rate is specified by the cost model variable handBreakoffRate (10mm2/sec in starting point VPEs).
• Support contact area: for all supports except DMLS supports, this is the total surface area of the both the following:
o Regions of contact between the support structure and the part
o Regions of contact between the support structure and the build platform.
For DMLS routings, this is the surface area of the region of contact between the support structure and the part. (The region of contact between the support structure and the build platform are handled by a different, base-removal process, with DMLS routings.)
For support structures whose bottom is connected to the build plate, the area of contact between the support and the part is the geometric property Supported Area, and the area of contact between the support and the build plate is Plate Contact Area. For support structures whose bottom is connected to the part, the contact area is the sum of the geometric properties Supported Area and Bottom Part Contact Area.
The following image shows a support (in purple) whose top and bottom are both connected to the part:
The following image shows a support whose top is connected to the part and whose bottom is connected to the build platform:
If the total contact area for a support is 0 (for example, due to a modelling error), removal time is the value of the cost model variable handBreakOffTime (5 seconds in starting point VPEs).
Manual Tool Base Removal Formulas
Cycle Time = Process Time * Adjustment Factor
Cycle time is the product of the following:
• Process time: this is the sum of the process times for each support structure that is in contact with the build platform (see formula).
• Adjustment factor (specified by the cost model variable cycleTimeAdjustmentFactor). This factor is 1 in aPriori starting point VPEs. VPE administrators can modify cycleTimeAdjustmentFactor in order to adjust cycle times across processes within the current VPE.
Process Time per Support Structure = Positioning Time + Removal Time
Process time per structure is the sum of the following:
• Positioning time: this is the time spent positioning the tool prior to disconnecting the bottom of the support structure. Each time is specified by the cost model variable handBreakoffPositioningTime (3 seconds in starting point VPEs).
• Removal time: depends on the area of contact between the support structure and the build plate (see formula).
Removal Time = Support Contact Area / Hand Breakoff Rate
Removal time depends on the following:
• Hand breakoff rate: area per unit time, looked up by process (DMLS, Material Jetting, Stereolithography) in the lookup table tblHandBreakoffRate.
If the lookup fails, the breakoff rate is specified by the cost model variable handBreakoffRate (10mm2/sec in starting point VPEs).
• Support contact area: this is the surface area of the region of contact between the support structure and the build plate, which is the value of the geometric properties Bottom Part Contact Area. (Regions of contact between the support structure and the part are handled by the Breakoff process.)