Coremaking—All Except Stock Core
The following sand casting processes rely on the formulas below:
• CO2 Cured
• Hot Box
• Isocure Gas
• Manual
• No Bake
• Oil Core
• Shell
See Coremaking--Stock Core for information on Stock Core expendable tooling.
Each cored feature has one associated coring process per core segment. By default, each cored feature is assumed to have a single-segment core, and so has one associated coring process. For manual coremaking, you can override the default by setting a GCD-specific setup option—see Customizing the Number of Core Segments.
Expendable Tooling Cost = Sand Cost / Final Yield
Expendable tooling cost (per core segment) is a function of the following:
• Sand Cost (see formula)
Sand Cost =
((Mass Sand per Segment * (1 – Sand Additive Fraction)) *
(Sand Unit Cost + Disposal Unit Cost)) +
Sand Additive Cost
Sand cost per core segment is the cost per segment of sand and sand additive. It depends on the following:
• Mass sand per segment. This is the mass of sand and sand additive. It is calculated based on the sand density, together with the volume of the core (including coreprint volume—see Coremaking Machine Selection) and the number of core segments. Sand density is obtained by looking up the sand type in the global lookup table sand. Sand type is specified by the toolshop property coreSandType.
• Sand additive fraction. By default, this is looked up by additive type in the table tblSandAdditives. Additive type is either None (the default, which indicates that no additive is used), or else the type specified by the user with the PSO Sand Additive Type. You can override the looked-up percent with the PSO Sand Additive Percent (see Melting Setup Options).
• Sand unit cost is obtained by looking up the sand type in the global lookup table sand. Sand type is specified by the toolshop property coreSandType.
• Disposal unit cost is the cost per kg for sand disposal. It is obtained by looking up the sand type in the global lookup table sand. Sand type is specified by the tool shop property coreSandType.
• Sand additive cost (see formula)
Sand Additive Cost = Sand Additive Rate * Sand Additive Percent * Mass Sand per Segment
Sand additive cost depends on the following:
• Sand additive rate. By default this is looked up by additive type in the table tblSandAdditives. Additive type is either None (the default, which indicates that no additive is used), or else the type specified by the user with the PSO Sand Additive Type. You can override the looked-up rate with the PSO Sand Additive Rate (see Melting Setup Options).
• Sand additive percent. By default, this is looked up by additive type in the table tblSandAdditives. Additive type is either None (the default, which indicates that no additive is used), or else the type specified by the user with the PSO Sand Additive Type. You can override the looked-up percent with the PSO Sand Additive Percent (see Melting Setup Options).
• Mass sand per segment is calculated based on the sand density, together with the volume of the core (including coreprint volume—see Coremaking Machine Selection) and the number of core segments. Sand density is obtained by looking up the sand type in the global lookup table sand. Sand type is specified by the machine property Core Sand Type.
Cycle Time = Process Time * Cycle Time Adjustment Factor
Cycle time is the product of the following:
• Process time (see formula)
• Cycle time adjustment factor: specified by the cost model variable cycleTimeAdjustmentFactor; 1 in aPriori starting point VPEs.
Process Time =
Coremaking Time / Number of Corebox Cavities + Core Assembly Time
Process time per core segment is a function of the following:
• Coremaking time: for processes other than Manual Coremaking, this is specified by the machine property Base Cycle Time. For Manual Coremaking, see the formula for Manual Coremaking Time, below.
• Number of corebox cavities: if the process setup option Corebox Cavity Calculation Mode set to Opportunistic (the default setting in starting point VPEs), the number of corebox cavities is the maximum number of cavities that will fit along the length direction of the coremaking machine. If the setup option is set to Single Cavity, the number of corebox cavities is 1. The default setup option setting is specified by the cost model variable coreboxCalcMode (Opportunistic in starting point VPEs). See Sand Casting Tooling—Core Making for more information.
• Core assembly time: this is 0 for a single-segment core; for a multi-segment core, this is 0 for the first segment and singleCoreAssemblyTime (60 seconds in the starting point VPEs) for each of the rest of the segments.
Manual Coremaking Time =
Sand Resin Mixing Time + Core Box Sand Blowing Time + Core Stripping Time
For the Manual Coremaking process, coremaking time is the sum of the following:
• Sand resin mixing time: this is the core mass divided by the mixing rate specified by the machine property Mixing Rate.
• Core box sand blowing time: this is the time to blow the sand into the corebox. It is the core mass divided by the blowing rate specified by the cost model variable coreBoxSandBlowingRate (300 kg/min in starting point VPEs).
• Core stripping time: this is the time for the sand to cure enough to be safely removed from the corebox. It is interpolated from values looked up by blowing time (in minutes) in the lookup table tblCoreCuring.
If the sand blowing time is greater than or equal to the table’s largest value for Bench Life Max, costing fails for the current GCD.
If the sand blowing time is less than the table’s smallest value for Bench Life Min, then core stripping time is the table’s smallest value for Stripping Time Min.
If the sand blowing time is between Bench Life Min and Bench Life Max for some table entry, then core stripping time is between Stripping Time Min and Stripping Time Max for that entry. In particular, if the blowing time is a certain fraction of the way from Bench Life Min to Bench Life Max, then the stripping time is that fraction of the way from Stripping Time Min to Stripping Time Max.