Benefits of Using Sand Casting

1. Nearly any alloy:

Sand castings can be readily produced in nearly any ferrous or non-ferrous alloy.  Some other casting processes will melt and pour super-alloys in a vacuum, but that is not typically done as a sand casting. Some materials cannot be “worked”, and must be produced as a casting.

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2. Low tooling cost:

The relatively low cost of tooling makes sand casting a process of choice for lower volume needs.  Patterns do wear so the material selected for the pattern (typically wood, plastic, or metal) will depend on the expected usage quantity of the part being produced. Though not necessarily cheaper in the short run, the use of machined (or “patternless”) molds may be a cost-effective option for components with expected lower usage over a longer period of time.

3. Versatile – Size, Weight, Shape:

Sand castings can be produced in weights from ounces to 200+ tons.  Through the use of cores, internal structures can be cast in place.  Shaped parts rely mainly on the imagination of the designer.  Most sand castings, however, will need at least some machined surfaces, either because of innate tolerance limits of the process, or the need to mate with other components.

4. Any Quantity:

Because the tooling cost can be minimal, sand casting may be appropriate for a single piece run.  Alternatively, there are automotive components that are produced using this process, so it may also be used in high volume applications.  Other elements of design and tolerance are often more important than quantity when selecting this as the preferred casting process. 

5. Timing:

The casting process itself may be quicker than some others, like investment casting, but it is important to consider the post-casting processes like machining that may be required when computing total lead times.

Concerns with Sand Casting

1. Lower Dimensional Accuracy:

No-bake molding can deliver better dimensional accuracy and repeatability than green sand molding, but this process will, on average, provide less precision than other common casting processes.

2. Pattern Maintenance:

While of lower cost than tooling for other casting processes, there is still an art to pattern creation. Patterns can be bulky so the storage must be managed; this is especially significant if the casting is produced infrequently.  Patternless molding can relieve some challenges of pattern storage and maintenance.  

3. Surface Finish:

Sand castings tend to deliver a rougher surface finish than other casting processes. That point may be moot if certain surfaces are machined anyway, or if surfaces in the as-cast condition are acceptable.
Below is a comparison of relative surface finishes that can be expected from various casting process:

Pros and Cons of different types of Casting Processes

There are various types of casting processes, each with its own set of benefits and disadvantages. Below, you will find the different casting processes, each with its advantages, disadvantages and recommended application.

Investment Casting

Also know as lost wax casting, investment casting is a process commonly applied in cases where both solid parts and complex, hollow cores are required.

Advantages

• It is able to deliver close dimensional tolerances.
• Both ferrous and non-ferrous metals can be casted using investment casting.
• It delivers a good as-cast finish.
• With investment casting, complex shapes, intricate core sections, finer details and thinner walls are possible.
• It offers a flexibility in design and is a useful process for casting alloys that are difficult to machine.

Disadvantages

• Investment casting has a higher cost associated with it. In fact, it is more expensive than Sand Casting, Permanent Mold and the Plaster Casting process.
• When compared to other types of casting processes, investment casting needs a longer product-cycle time.
• There is a limitation on the size of parts that can be casted.

The advantages of this casting process overshadow costs when permanent mold and sand casting cannot deliver the desired complexity needed. Costs are also reduced by the quality surface finish investment casting delivers, reducing the cost of both machining and tooling.

You can learn more about this process, metals that can be casted, precision, tolerances and more by visiting our Investment Casting page.

Sand Casting

A process typically relying on silica-based materials, sand castings process involves finely ground, spherical grains tightly packed together into a smooth molding surface.

Advantages

• This is the least expensive process when producing small quantities (normally less than 100) and also boasts with the least expensive tooling.
• With sand casting, manufacturers are able to cast very large parts.
• Both ferrous and non-ferrous metals can be casted using this process.
• A low post-casting tooling cost.

Disadvantages

• Sand casting's dimensional accuracy is less than that delivered by other processes.
• This process requires large tolerances.
• The surface finish for ferrous casts delivered by this process usually exceeds 125 RMS.
• Castings produced with this proceed usually exceeds the calculated weight.

The advantages of sand casting process are more beneficial in cases where strength to weight ratios allows for it. Yielding a lower degree of accuracy, it does on the other hand offer low machining costs. For more information on this process, please visit our Sand Casting page.

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Die Casting

Die casting involves the molding of materials under high pressure, and consists of Cold-Chamber Conventional Die Casting, Hot-Chamber Conventional Die Casting and Multi-Slide Hot-Chamber Die Casting for aluminum, brass, magnesium and zinc.

Advantages

• Die casting is able to deliver parts that has a good dimensional tolerance.
• Parts produced using die casting require a minimal amount of post machining.
• This casting process also delivers an excellent part to part consistency, ideal for large production scales.
• It is a cost effective process when used for a high volume production run.
• This process is suitable for metals with a relatively low melting point, such as aluminum, lead, magnesium, zinc and some copper alloys.

Disadvantages

• This process is only an economically sound option for a large production quantity, as the tooling costs for die casting are expensive.
• In this process, it is difficult to guarantee minimum mechanical properties and is thus do not function as structural parts.
• This process is also not recommended for hydrostatic pressure applications.
• There is a limit on the size of parts that can be casted. It is a suitable process for castings of about up to 75 pounds.

While it is an economically viable option for large production runs, die cast parts' mechanical properties cannot be assured, resulting in these parts not having a structural function. It is however a good process to opt for in cases where a large quantity of the part is needed, the parts produced will not have a structural function and in cases where parts will not be subjected to hydrostatic pressure.

For further information on this process, please feel free to visit our Die Casting page.

Permanent Mold Casting

Permanent mold casting is a process used in which permanent molds consists of mold cavities, machined into metal die blocks and appropriate for repetitive use.

Advantages

• This type of casting process is less expensive than die casting or investment casting.
• Casting delivered using this process are dense and pressure tight.
• Permanent mold casting is able to deliver a closer dimensional tolerance than sand casting is able to.
• The repeated use of molds are possible.
• It has a rapid production rate combined with a low scrap rate.

Disadvantages

• This process is only able to cast non-ferrous metals.
• Permanent mold casting has a higher cost of tooling than sand casting has.
• It becomes less competitive with sand casting in cases where three or more sand cores are required in the process.
• Because of the high tooling cost associated with permanent mold casting, it is only a financially viable option for high production runs.
• Limited to small castings with a simple design exterior.*

These types of casting processes are used in cases where parts are subjected to hydrostatic pressure and is perfect when casting parts that have no cores, a low profile and is part of a large production run (usually more than 300).

*Recent developments do allow for more complex castings, such the aluminum engine blocks and heads produced.

Learn more about our services and processes by visiting our Permanent Mold Casting page.

Plaster Casting

Plaster casting is a casting process with similarities to sand casting. Instead of using sand in the process, a mixture of water, gypsum and strengthening compounds are used.

Advantages

• Plaster casting is capable of delivering a closer dimensional tolerance than sand casting is able to.
• It delivers a smooth, as-cast finish.
• Casting larger parts using this process is less expensive that it would be when using investment casting processes.
• Intricate shapes with finer details are possible.
• Thinner, as-cast walls are also delivered by this casting process.

Disadvantages

• Plaster casting requires a minimum of a 1 degree draft.
• It is a more expensive process when compared to permanent mold and sand casting.
• This process may require the frequent replacement of plaster molding materials.

Though a more expensive process than most sand casting processes, it is a more economically sound option when a good surface finish quality is needed.

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