Operation-level Feasibility and Routing
Below are the sheet metal operations that have associated feasibility rules, grouped by GCD type. Each operation is accompanied by necessary conditions for the operation’s selection. aPriori checks the operations in the order specified by the operation templates, and selects the first operation for which the current GCD satisfies all the necessary conditions. Note that Laser Punch and Plasma Punch reflect the rules listed for Laser Cut, Plasma Cut, and Turret Press.
Blank
• Punching
o Blank has at least one straight edge or at least one small, curved edge; that is, the blank either has at least one straight edge or has at least one non-straight edge whose minimum radius of curvature (Min Convex Radius or Min Concave Radius) is less than or equal to half the value of the machine property Max Punch Size (which specifies the diameter of the largest punch).
Complex Hole
• 3DLaserCutting
o Meets any GTOL tolerance requirements.
• LaserCutting (also applies to Laser Punch)
o GCD is not flanged.
o Meets any GTOL tolerance requirements.
• OxyFuelCutting
o Hole diameter equals or exceeds minimum hole diameter.
o Meets any GTOL tolerance requirements.
• Perforating
o There are at least 19 other holes with the same perimeter and area as this hole.
o There are at least two nearby holes with the same perimeter and area, where a is a nearby hole for b if and only if there is a LIIES_NEAR relation that relates a and b and that has a distance property less than or equal to:
b’s SER width, for holes whose holeType is smallRectangular
One and a half times b’s SER width, for holes whose holeType is smallObround
Diameter of b’s smallest enclosing circle times the value of the machine property perforationProximityThreshold, for holes whose holeType is smallComplex
o Meets any GTOL tolerance requirements.
• PlasmaCutting (also applies to Plasma Punch)
o Hole diameter must exceed minimum hole diameter.
o Meets any GTOL tolerance requirements.
• Punching
o Hole’s SEC Diameter (diameter of the hole’s smallest enclosing circle) is less than or equal to the value of the machine property Max Punch Size.
• WaterjetCutting
o GCD is not flanged or chamfered.
o GCD is not flanged or chamfered
o Ratio of wall thickness to part thickness is less than the plant variable waterjetWallThicknessToDepthRatio.
o Hole width may not be less than the kerf width specified in the plant variable waterjetKerf.
Edge
• Punching
o Edge either is straight or is curved and small; that is, the edge either is straight or is non-straight and has a minimum radius of curvature (Min Convex Radius or Min Concave Radius) that is less than or equal to half the value of the machine property Max Punch Size (which specifies the diameter of the largest punch).
• Plasma Bevel Cutting
o GCD property Edge Type is Chamfer.
o Plasma bevel cutting is enabled. By default in starting point VPEs, chamfers are assumed to be created by secondary machining, so plasma bevel cutting is disabled. VPE administrators can customize the default with the cost model variable defaultPlasmaBevelCuttingStatus (true for enabled or false for disabled). Users can override the default on a part-by-part basis with the setup option Enable Plasma Bevel Cutting—see Plasma-Cut-specific Inputs. o If there are chamfers on both the top and bottom sides of the part, this chamfer is on the side of the part with the longest total chamfer length (otherwise the chamfer is assumed to be created by secondary machining).
Perimeter
• Waterjet
o The perimeter GCD must be the one associated with the part height.
Simple Hole
• 3DLaserCutting
o GCD is not flanged.
o GCD is not blind.
o Meets any GTOL tolerance requirements.
• LaserCutting (also applies to Laser Punch)
o GCD is not flanged.
o GCD is not blind.
o Meets any GTOL tolerance requirements.
• OxyFuelCutting
o GCD is not threaded.
o GCD is not countersunk.
o GCD is not flanged.
o GCD is not blind.
o Meets any GTOL tolerance requirements.
• Perforating
o There are at least three other holes with the same perimeter and area as this hole
o There are at least two nearby holes with the same perimeter and area, where a is a nearby hole for b if and only if there is a LIIES_NEAR relation that relates a and b and that has a distance property less than or equal to b’s diameter.
o Meets any GTOL tolerance requirements.
• PlasmaCutting (also applies to Plasma Punch)
o GCD is not flanged.
o GCD is not blind.
o Meets any GTOL tolerance requirements.
• TurretPress (also applies to Laser Punch and Plasma Punch)
o GCD is not blind.
o Meets any GTOL tolerance requirements.
• Waterjet
o The hole axis must be parallel to the cut direction of the part perimeter.
o GCD is not blind.
o GCD is not countersunk.
o GCD is not flanged.
o Meets any GTOL tolerance requirements.
o Ratio of wall thickness to part thickness is less than the plant variable waterjetWallThicknessToDepthRatio
o Hole width may not be less than the kerf width specified in the plant variable waterjetKerf.
Straight Bend
• Bending
o GCD is linear.
o GCD has no formed gussets.
o GCD does not intersect or end any other bend or form.
o Minimum bend radius is greater than or equal to the product of the part’s thickness and the cost model variable minBendRadiusRatio (0.5 in starting point VPEs).
o Minimum bend radius is less than the cost model variable maxBendBrakeRadius (42mm in starting point VPEs).
o Bend length does not exceed the machine property Max Bend Length.
o Bend length is greater than or equal to botth the stock height and the cost model variable minBendLengthBendBrake (10mm in starting point VPEs).
o Bend flap length does not exceed the bend’s minimum bend radius plus 2.5 times the part thickness, unless the bend is part of a multibend (that is, unless it bears the LIES_NEAR relation to another bend, at a distance that is less than the bend’s minimum bend radius plus 2.5 times the part thickness).
• 2 Roll Bending
o GCD is linear.
o GCD is not inside a complex hole.
o Bend radius must be greater or equal to the minimum radius for 2 roll bending ((plant variable min2RollBendingDiameterRatio * Top RollDiameter)/2).
o GCD length is less than the maximum Roll Working Length.
• 3 & 4 Roll Bending
o GCD is linear.
o GCD is not inside a complex hole.
o Bend radius must be greater or equal to the minimum radius for 3 roll bending (machine variable Minimum Single Pass Diameter)/2).
o GCD length is less than the maximum Roll Working Length.