Sand Casting Cost Model Overview

This overview section summarizes assumptions and limitations of the following aspects of the model:

Sand Casting General Process

In general, casting costs are determined by aggregating material, labor, machine, and tooling costs.

aPriori represents sand casting as a process sequence that includes moldmaking and optional coremaking processes.

There are a number of alternative moldmaking processes:

  • Vertical Automatic: Uses high volume machines such as DisaMatic and Loramendi.

  • Horizontal Automatic: Uses high volume machines such as Hunter HMP and Roberts Sinto FBx.

  • Manual Std Moldmaking: Appropriate for manual mold-making at low and medium production volumes. With this process, standard flasks are filled with sand, compacted, and transported (typically by conveyor) to a pouring station, and then on to a central cooling and breakout area.

  • Manual Floor Moldmaking: Appropriate for casting large parts that require the flask to stay in place on the foundry floor. This process is used when it is not practical to move the flask.  Used for large castings, the flask is built around the pattern and core boxes, and the crucible is brought to the flask for pouring. The flask then stays in place on the floor for cooling and breakout.

  • Manual Pit Moldmaking: Appropriate for casting of very large parts in a pit. With this process, the pit serves as the drag and a wooden frame on top of the pit provides the cope and incorporates the feeder system.

There are also provides a number of alternative coremaking processes:

  • No heat required: with these processes, the binder in the sand becomes rigid without heat. Modern core making tends to prefer no-heat processes with minimum environmental disposal problems.

    • Isocure Gas: popular cold box core making process introduced in 1968 by Ashland (phenolic urethane cold-box binder). The starting point cost model prefers this method. Cores can be as small as 3/8” (9.5 mm).

    • No Bake: developed in the 1960s, this method uses sand mixed with a chemical binder. The mixture cures at room temperature, but curing is relatively slow. Core sizes can go down to about 3” (76.2 mm). The method is often used for large cores, especially for floor molding.

    • Manual Coremaking: for very large cores. Similar to No Bake, but cores are made by hand; a vibratory table is used to compact the sand into the corebox. This is auto-selected, by default, for cores that are too large for No Bake.

    • CO2 Cured: similar to Isocure, this process uses CO2 gas to set the binder. The process is sometimes known as Ecolotec. Cores can be as small as 3/8” (9.5 mm). This method is never auto-selected in starting point Digital Factories; it must be manually included.

  • Heat required: These processes require heat for the binder in the sand to become rigid.

    • Stock Core: limited to Simple Hole GCDs. Stock cores are made by a relatively inexpensive extruder that extrudes a sand mixture through an extruding head. Usually, stock cores are limited to simple hole shapes with standard (stock) diameters. A stock core can be used if the hole doesn’t have a draft and if the hole axis is perpendicular to the parting direction of the mold.

      Hot Box: developed about 1953. Hot box cores use a thermoset resin and apply heat. Core sizes go down to about 2” (50.8 mm). This method is often used for large cores. Must be manually included.

    • Oil Core: uses an oil-based binder. The core must be baked to set. Core sizes can be as small as 3/8” (9.5 mm). Must be manually included.

    • Shell: invented in 1947 by J. Croning. With this method, sand is blown into a heated box and the sand pressing against the box sets to form a shell. The remaining sand in the center is poured out and can be reused. The result is hollow core. The core is baked and is considered hollow. Shell cores allow excellent surface finish, but the baking is slow. Foundries sometime buy shell cores. Core sizes can be as small as 3/8” (9.5 mm). Must be manually included.

See Coremaking Feasibility and Routing for Sand Casting for more information.

If you have licensed the appropriate modules, your routing can include optional machining, heat treatment, and surface treatment processes, as well as testing, inspection, and packaging processes (which are part of the process group Other Secondary Processes).

Part Geometry for Sand Casting

Feasible geometries for casting are limited by machine capabilities and by the selected Digital Factory’s minimum castable diameter for holes and voids.

A part is geometrically feasible for sand casting only if it satisfies the following requirements:

  • The selected Digital Factory supports machines of the required types that can accommodate the part’s size and weight, as well as core sizes.

  • Hole diameter and void box sizes are larger than the plant variable minSandCastableHoleDia for the selected Digital Factory.

See GCD Extraction for Sand Casting, Machine Feasibility and Selection for Sand Casting, and Feasibility and Routing for Sand Casting for more information.

Materials for Sand Casting

Starting point Digital Factories include the following types of materials, among others:

  • Aluminum

  • Aluminum Bronze

  • Ductile Iron

  • Gray Iron

  • Cast Steel

  • Commercial Bronze

  • Ductile Iron

  • Free-Cutting Brass

  • Lead (cast)

  • Magnesium

  • Manganese Bronze

  • Medium-Carbon Steel

  • Silicon Brass

  • Stainless Steel

  • Yellow Brass

See Material Selection for Sand Casting for more information. For sand casting, users can specify the unit cost of any metal additive, such as flux; see User Inputs for Sand Casting.

Machines for Sand Casting

The following tables list important property value ranges of the machines supported for the various central processes:

 

Horizontal Automatic (Beardsley & Piper, DisaMatic, Hunter, Roberts Sinto)

Property

Low End

High End

Flask Height (mm)

254.0

584.2

Flask Length (mm)

482.6

812.8

Flask Width (mm)

355.6

762.0

 

Vertical Automatic (DisaMatic, Loramendi)

Property

Low End

High End

Flask Height (mm)

199.9

400.05

Flask Length (mm)

398.78

1,100.07

Flask Width (mm)

398.78

1,199.9

 

Manual Std Moldmaking (Virtual)

Property

Low End

High End

Flask Height (mm)

101.6

609.6

Flask Length (mm)

305.0

1,828.8

Flask Width (mm)

304.8

1,524.0

 

Manual Floor Moldmaking (Virtual)

Property

Low End

High End

Flask Height (mm)

304.8

2,000.0

Flask Length (mm)

610.0

4,000.0

Flask Width (mm)

609.6

4,000.0

 

Manual Pit Moldmaking (Virtual)

Property

Low End

High End

Flask Height (mm)

2,489.0

5,000.0

Flask Length (mm)

4,013.0

18,000.0

Flask Width (mm)

4,013.0

9000.0

 

See Machine Feasibility and Selection for Sand Casting for more information.

Tooling for Sand Casting

Users can specify the number of cavities and whether or not the system should check for drafts, rounds, or the minimum thickness feasibility. Users can also specify the mold pattern material, as well as the type, unit cost, and proportion of any sand additive.

See Tooling Cost for Sand Casting and User Inputs for Sand Casting for more information.