This section contains the following subsections:

If aPriori is configured to automatically select a molding machine, it selects the machine with the lowest flask volume that satisfies all the machine feasibility rules.

aPriori selects only from preferred machines, if there is a feasible preferred machine and the cost model variable usePreferredMachines is set to true (the default in starting point VPEs). If there is no feasible preferred machine, or if the cost model variable usePreferredMachines is set to false, aPriori selects from all machines. A machine is preferred if the machine property isPreferred (typically displayed as Is Preferred) is true.

The feasibility rules require that the mold required for the part can fit on the machine. More specifically, a machine is feasible only if both the following are true:

aPriori calculates the mold dimensions and clamp force required for a given part based on a number of factors, including the minimum required number of cavities in the mold. If you don’t use the PSO Number of Cavities (see User Inputs), the minimum required number of cavities is 1, so aPriori finds a machine that can accommodate at least a single-cavity mold.

By using the PSO, you can specify the number of cavities explicitly or specify that aPriori should use the combination of machine and number of cavities that results in the lowest per part cost. Calculation of clamp force is described in Required Clamp Force. Calculation of the number of cavities assumed for cost estimates is described in Number of Mold Cavities.

To manually select a machine for a given process, select Edit > Routing Selection in the Manufacturing Process pane, right-click on the process in the Routing Selection window, and select Machine Selection from the context menu (see also Selecting a machine for an operation in Manufacturing Process Information).

aPriori selects the feasible machine (see below) with the smallest weight capacity per part:

The number of parts that can fit on the machine depends on the machine's Shakeout Type:

aPriori selects only from preferred machines, if there is a feasible preferred machine and the cost model variable usePreferredMachines is set to true (the default in starting point VPEs). If there is no feasible preferred machine, or if the cost model variable usePreferredMachines is set to false, aPriori selects from all machines. A machine is preferred if the machine property isPreferred (typically displayed as Is Preferred) is true.

Space constraint: The maximum number of parts that can satisfy the space constraint is determined as follows:

Weight constraint: The maximum number of parts that can satisfy the weight constraint is the result of rounding down the quotient of the machine's weight capacity and the part weight:

Machine weight capacity is specified by the machine property Weight Capacity. Part weight is the product of the part's Volume and the material's Density.

Feasible machine: A machine is feasible if both the following hold:

aPriori selects the smallest feasible machine (by weight capacity) that can accommodate the part’s weight. Weight capacity is specified by the machine property Max Weight.

aPriori selects only from preferred machines, if there is a feasible preferred machine and the cost model variable usePreferredMachines is set to true (the default in starting point VPEs). If there is no feasible preferred machine, or if the cost model variable usePreferredMachines is set to false, aPriori selects from all machines. A machine is preferred if the machine property isPreferred (typically displayed as Is Preferred) is true.

A machine is feasible only if its weight capacity exceeds the part weight. In addition, a machine that uses OxyFuel is not feasible for aluminum parts.

There are four types of cleaning machines, all of which use shot blast:

The machine type is specified by the machine property Type.

aPriori selects the smallest machine (by weight capacity) that is feasible for the current part (see below). aPriori selects only from preferred machines, if there is a feasible preferred machine and the cost model variable usePreferredMachines is set to true (the default in starting point VPEs). If there is no feasible preferred machine, or if the cost model variable usePreferredMachines is set to false, aPriori selects from all machines. A machine is preferred if the machine property isPreferred (typically displayed as Is Preferred) is true.

A machine is feasible if it can accommodate all the following:

The minimum number of parts in an economic load is specified by the machine property Min Number Parts.

aPriori selects the smallest machine (by weight capacity) that can accommodate the part’s weight. Weight capacity is specified by the machine property Max Weight.

aPriori selects only from preferred machines, if there is a feasible preferred machine and the cost model variable usePreferredMachines is set to true (the default in starting point VPEs). If there is no feasible preferred machine, or if the cost model variable usePreferredMachines is set to false, aPriori selects from all machines. A machine is preferred if the machine property isPreferred (typically displayed as Is Preferred) is true.

For each occurrence of each coremaking process (except Stock Core), aPriori selects the machine with the smallest corebox capacity that is feasible (see below). aPriori selects only from preferred machines, if there is a feasible preferred machine and the cost model variable usePreferredMachines is set to true (the default in starting point VPEs). If there is no feasible preferred machine, or if the cost model variable usePreferredMachines is set to false, aPriori selects from all machines. A machine is preferred if the machine property isPreferred (typically displayed as Is Preferred) is true.

A coremaking machine is feasible if it can accommodate a corebox with at least one cavity for one segment of the core for the GCD associated with the process occurrence. Note that each occurrence of each coremaking process has exactly one associated GCD. Note also that by default, each core has a single segment, but you can override the default on a GCD-by-GCD basis—see Customizing the Number of Core Segments.

For processes other than Manual Coremaking, a machine’s corebox capacity is given by the machine properties Max Corebox Length, Max Corebox Width, and Max Corebox Height. A machine can accommodate a GCD if these dimensions equal or exceed the dimensions of the corebox required for the GCD. For a single-segment core, the dimensions of the required corebox are the dimensions of the GCD’s smallest enclosing box, extended to account for coreprints (extensions of sand for hanging the core in the mold), and supplemented by the corebox wall thickness (specified by the cost model variable coreboxLengthAllowance--19mm in starting point VPEs). For a multi-segment core, the dimensions of the required corebox are the dimensions of the GCD’s smallest enclosing box divided by the number of segments, extended to account for coreprints, and supplemented by the corebox wall thickness.

The GCD properties Dir CorePrints Box Length, Dir Core Prints Box Width, and Dir Core Prints Box Height indicate which dimensions should be extended, and whether the dimension should be extended in one or both directions. For example, if Dir Core Prints Box Length is 0, this indicates that an extension along the length dimension is not required (because both directions are blocked by the part); if Dir Core Prints Box Length is 1, this indicates that the length should be extended in one direction to account for coreprints (because the other direction is blocked by the part); if Dir Core Prints Box Length is 2, this indicates that the length should be extended in both directions to account for coreprints (because neither direction is blocked).

The cost model variable lengthCorePrint (10mm in starting point VPEs) indicates the extension length in each direction. So, for example, if Dir Core Prints Box Length is 2, the GCD’s box length dimension is extended by 10mm in each direction (20mm total), in starting point VPEs.

For Manual Coremaking, the machine represents a muller and vibratory core table. Machines are constrained by the total mass of all the part’s cores, rather than by individual core dimensions. A machine’s corebox capacity is given by the mass-valued machine property Max Capacity.

Machine selection for Refractory Coat Oven Dry picks the lowest-volume feasible machine. A machine is feasible if both the following hold:

A core or mold is oven-dryable if it can fit in the largest available oven. Molds and cores that are too large for any available oven are air dried.

Note that the cost model assumes the use of a single oven for a given part, that is, the cost model assumes that the same oven is used for a part’s mold (if it is oven-dried) as well as for all the part’s oven-dried cores.

Machine volume is the product of the machine properties Bed Length, Bed Width, and Bed Height.

In starting point VPEs, which assume a spacing factor of 0.8, an oven can accommodate a core or mold (or, equivalently, a core or mold can fit in an oven) if all the following hold:

Administrators can configure the spacing factor with the cost model variable defaultRefractoryCoatOvenSpaceAvailableFactor (0.8 in starting point VPEs).

See also Mold and Core Bounding Box Dimensions.