There are various characteristics that businesses look for in custom metal parts. Strength, size, material type, grain flow, and cost are some of the most important, and they are determined by the type of processing procedure used. 

If you want to learn more, please visit our website.

Forging and casting are the most common.  

During the forging process, metal is pressed or hammered to give the desired shape, while in casting it is melted and then poured into a mold shaped in the desired form.

Both processes have particular advantages and disadvantages depending on the characteristics, cost, and service requirements that are needed.

The following sections will cover these key differences specifically in the areas of strength, types, sizes, alloy selection, additional processing, cost, and grain flow.

Strength or Structural Integrity

The stronger material is, the more likely it is to be able to maintain its structural integrity under various harsh conditions. This durability ensures functionality and safety.

Metals should be strong enough to maintain their structural integrity and perform at peak levels both under normal operational conditions and those that exceed them.

There are four ways in which the strength of metal can be measured.

Tensile strength refers to a material’s ability to withstand pressure or forces that would normally separate or pull a metal apart.

Compressive strength is the amount of pressure a material can tolerate without fracturing—in other words, the load it can bear. 

Shear strength denotes the capacity to withstand or resist shear, that is, the structural strain produced by pressure.

Torsional strength is the ability of a material to withstand twisting loads due to torque. 

Of the two processes we’ve mentioned in the previous section—forging and casting—forging produces a far stronger metal. This is because the process of forging alters the metal’s granular layout within and on top of the surface, making it more uniform. 

Forging also helps to eliminate holes (voids and gas pockets) that would normally decrease both the structural and chemical integrity of the material.  

On the other hand, the casting process tends to produce more porous holes since the metal shrinks from its thicker to its thinner sections during the process.

If you require strong material to maintain functional and structural integrity under normal and severe conditions such as is the case in the production of aerospace, railway, and ship components, then creating custom metal parts through forging is recommended. 

Product Type and Size

Not all products need to be strong and rigid. Some ought to be more pliable and flexible so they can be formed into complex and aesthetic designs. 

For those applications, casting is usually more appropriate, as it is more difficult to shape metals made through forging.

The casting process allows for more complex shapes to be formed since the metal is melted first, which means it can be easily poured into a pre-shaped mold or die. 

Moreover, since the metal is melted during the casting process, larger products can be created, even those measuring up to 400 to 4,000 tons. 

Therefore, the size of a particular product or application will also dictate which process should be used.

However, casting is not solely delegated to only large-size applications. Since it adheres to very tight tolerances, it is very useful even in forming smaller products with complicated geometrical designs.

Additionally, casting is more cost-effective than other machining processes, including forging, because it promotes material efficiency—five times higher than standard machining—meaning that more parts can be made in less time. 

That is not to say that forging does not have its value, especially when strength and reliability are the primary concerns. It is just that casting is more useful when creating larger products with specific design requirements.

To get a better idea of which process is more useful for your specific project, take a look at the following list of products created through both methods.

Forged ProductsCasted ProductsAgricultural Machinery & EquipmentHeavy Construction EquipmentOil Field ApplicationsHeavy Farming EquipmentHand ToolsHeavy Mining EquipmentGeneral Industrial EquipmentMachining ToolsRailroad EquipmentChemical MachineryOff-Highway EquipmentPetroleum MachineryAerospace ComponentsDefense VehiclesValvesArtilleryFittingsMunitionsElectrical Machines (motors, pumps, generators, compressors)Household AppliancesGardening ToolsArt & Decorative Objects (sculptures, lamps, furniture)

To summarize, the forging process is ideal for parts and applications that need to be strong, tough, and resistant to various mechanical forces. 

On the other hand, casting is ideal for larger parts with detailed and complex shapes, patterns, and internal cavities.  

Alloy Selection

As forging and casting are different processes, they aren’t always used with the same types of alloys. 

Alloys are a combination of metals and non-metals, which are mixed and blended to enhance the desirable properties of a metal, such as corrosion resistance, tensile strength, and toughness.

It is important to choose the right alloy for your project because doing so will help reduce wear and tear, extend product life, and help increase overall performance. 

After the alloy is chosen, the process that best compliments the alloy must be selected. The selection process will primarily depend on whether forging or casting can shape and mold the alloy to exact specifications.  

Below is a list of alloy metals that are typically used in the forging process, and those that are more suited for casting.

Alloys Typically Used in ForgingAlloys Typically Used in CastingAlloy SteelNickel AlloysMicroalloy SteelCobalt AlloysStainless SteelAluminum AlloysCarbon SteelLead AlloysAluminumStainless SteelCopperCarbon SteelTitaniumIron (gray, white, ductile)MagnesiumSiliconNickelZincIronMagnesiumCobalt

As you can see in the chart, some alloys are equally suitable for both processes, so the choice of one instead of the other will depend on other factors listed in this guide. 

What is more, the above lists are not complete and there are many other combinations of metals and non-metals that can be used for both processes. 

In general, forging has a more limited selection when it comes to alloys, while casting can utilize almost any type of metal during its process.

Secondary Processing

Both forging and casting often rely on secondary operations to complement them. However, forging tends to require fewer of them. 

Secondary processes are additional manufacturing processes that are needed to enhance and refine the formed product in some way.

There are many types of those operations, but the most popular ones include:

• Punching
• Drilling
• Tapping
• Threading
• Bending
• Swaging
• Coining
• CNC machining
• Heat treating
• Plating/coating
• Metallurgical testing

They provide the following benefits:

• Improved product appearance
• Increased corrosion resistance
• Prolonged product life cycle
• Increased product value
• Additional product features
• Lower cost

The reason forging requires fewer secondary processes lies in the fact that forging methods can be utilized on their own to get as close as possible to the desired specifications.

Of the different forging methods, the most common ones are:

• Open die forging
• Rolled ring forging
• Impression die forging

And since these three forging methods pretty much ensure the main aims of forging—predictable strength and strong performance—not much is needed after they are implemented. 

However, some secondary actions are commonly used after the initial forging process is completed.

Punching, straightening, and trimming are often employed after forging to ensure and improve the dimensional accuracy of fittings.

Cleaning methods like blasting, tumbling, or picking may also be used to clean the forgings if needed.

Casting, on the other hand, has more secondary processing requirements that are essential in creating smoother finishes, optimal sizes, and increased protection against oxidation.

The following ones are used most frequently:

• Machining
• Sealing (paint, plating, powder-coating)
• Bluing
• Oil treating
• Assembling (if done on-site)

The above processes are particularly common in conjunction with casting, since the process itself only deals with the formation of a part, and not its assembly, protection, or final surface finish.

Many custom-metal part manufacturers offer all or most secondary processes that may be required after casting or forging is completed, so there is usually no need to go to a different provider.

Cost

When it comes to cost-effectiveness, there is no definitive answer as to which of the two processes is more expensive.

The price of forging or casting will depend on various factors surrounding the formation and completion of a product. 

Some of those factors include:

• Production volume
• Shape complexity
• Types of alloys used
• Required secondary operations
• Added specifications

As a general rule, however, forgings are less expensive when they are purchased in medium to large lot sizes and castings are less costly when smaller lot sizes are bought.

However, castings can also be cost-effective when purchased in medium to large lot sizes, depending on how many secondary options are needed after they have been acquired.

As far as the cost of raw materials goes, those required for casting are usually less expensive than those for forging. This is because casting requires fewer initial steps and therefore less machinery to complete.

Also, the preliminary process of turning ingots into billets is eliminated during the casting process. 

The price of tooling can also be eliminated for castings since it is usually not needed. 

However, keep in mind that some forging methods don’t require tooling either, making them cost-competitive with castings. For instance, such is the case with open die forgings (ODF).

The machining costs associated with casting and forging are almost identical. Nevertheless, since forged alloys like stainless steel tend to have finer grains, machining them is often easier and therefore less costly. 

Secondary operations will play a major role in the final cost of the manufacturing process. 

Since casting tends to require more of them, it can turn out to be more expensive than forging, even though, when no secondary processes are required, its general costs are often lower than those of forging.  

Therefore, the final costs depend on which casting method or forging method is chosen, as well as how many of the above-mentioned factors are involved in the overall manufacturing process of a particular application.  

This is precisely why it is always recommended to contact a metal manufacturer and ask which variables will most likely pertain to the casting or forging of your specific product. 

You will get efficient and thoughtful service from G-Top.

The information they supply you with will help you determine which one will be more economical for your project requirements. 

Grain Flow

Grain flows are fiber-shaped lines that appear on metal surfaces in the direction of metalworking (shaping) during the forging process.  

Grain flow can help strengthen metal surfaces, reduce fatigue, and increase mechanical properties. 

Casting, however, does not produce any grain flow and therefore does not provide its benefits to the formed product. 

What is more, because there is no grain flow, casting can result in metallurgical defects, such as:

• Hot tears
• Hot spots
• Cold shut
• Slag inclusions
• Gas porosity
• Shrinkage
• Mold

The directional strength (directional alignment or grain flow) produced during forging creates a refined microstructure on the surface of the metal. This gives it higher tensile strength, impact toughness, fracture toughness, fatigue strength, and ductility. 

Additional benefits that are derived from directional grain flows include:

• Low machinability variation
• Consistent finish levels
• Stable dimensional characteristics
• Reproducible heat treatment response

Applications such as surgical and dental instruments, hand tools and hardware, as well as aerospace and automotive components need the additional properties produced by grain flow.

It ensures their functionality under harsh conditions and increases their longevity of use. 

Unlike casting, which produces a random grain distribution that reduces impact strength, forging helps to produce longitudinal grain flow across metal surfaces.

This greatly increases their overall strength and resistance to impact.  

Therefore, if higher strength, toughness, and fatigue resistance are primary requirements, then forging would be the obvious choice.

The casting process will not be able to supply any grain flow and so none of the required attributes. 

Conclusion

Neither of the metal manufacturing processes is categorically better than the other. 

Instead, you can choose between casting or forging depending on the type, size, alloy composition, cost, and strength that your project requires.

You may need other secondary manufacturing processes apart from casting and forging to fulfill the demands of your project, which will also affect the time and the resources it takes to complete it.

Since there are so many variables affecting the formation of custom metal products and parts, it is best to consult a metal manufacturer to help you determine which process is best suited for your application and budget. 

Casting vs. Extrusion vs. Forging

When it comes to manufacturing metal parts and components, there are often multiple ways to achieve the same end result. Casting, extrusion, and forging, to name a few, are all reliable methods of producing metal products. Each has its own unique capabilities and pros and cons. Which is the best option for manufacturing your parts at the best possible costs?

What are Metal Castings?

In some casting methods, metal in ingot or scrap form is heated until it reaches a molten state and the right specifications. Once they have achieved this, the molten metal is poured into a prepared sand cast mold; or injected into a custom tool steel mold for die casting; or an aluminum or steel die for investment casting to achieve the desired design required. The molten metal immediately cools in the sand mold or die and solidifies into the desired cast metal part required. Some castings may require machining and/or a surface finishing to obtain the final required part.

What are the Types of Castings?

While there are several different casting methods, die casting, sand casting, and investment casting are the most commonly used. To achieve the best suited and most cost-effective casting method, one must consider the metal or alloy to be used, the dimensions, the geometry, the weight of the part and the quantity. Every casting method uses a different process to deliver an acceptable cost-effective part.

In general, casting is the preferred method used to produce complex geometrical industrial metal parts. Molten metal flows much like a liquid so it therefore completely fills all areas of a complex mold design to achieve the exact part required. This also makes casting the best choice for parts that need internal cavities or voids, such as valve and pump bodies.

With certain exceptions at the extreme ends of the spectrum, there are no size limits for a sand casting as most other methods have limitations. Some Casting Methods can also maintain very high dimensional accuracy. a near net shapes as well as very good surface finish. Industry-standard tolerances do increase with casting size and the casting process.

 

 What are the Advantages and Disadvantages of Metal Casting?

PROS of CASTING

CONS of CASTING

Holds tighter tolerances in complex part designs. With some processes, very thin wall thickness

May result in internal porosity, unintentional surface voids, and other imperfections

Produces complexed design parts along with cores or voids. The cast part requires less machining than some other manufacturing methods

If required, parts are not as tough as those created by other processes, such as forging and have a lower impact & pressure resistance

Generally lighter than otherwise-identical parts produced by other methods and therefore less expensive. Some processes have a very good surface finish so less preparation for coating

Generally requires close operator supervision to ensure the best quality. Sand casting does not provide the best surface finish

Part design modification to dies or molds is faster, easier and less costly.

May require more machining in critical areas of the part

What are Metal Extrusions?

The extrusion process involves using a high-pressure press that forces a metal billet through an outlet, called a die, which is smaller and/or a differently-shaped cross-section that matches the desired shape of the bar or extruded shape required. A nearly unlimited number of cross-sections can be produced using the extrusion method.

The resulting profile can be as long as is necessary. In some cases, where small parts are made from the shape, the profile is cut into shorter lengths. More than any other metal forming process, the extrusion process creates various mechanical properties which may be required in the final part being produced. The process produces elongated grain structure that increases the raw material’s mechanical strength.

What's the difference between Hot and Cold Extrusions?

Hot extrusion, with the metal above its recrystallization temperature, it helps eliminate pores and voids in the material, breaks up inclusions in the raw metal that can cause weakness, and recrystallizes the material into a finer grain structure. This process produces lengths of Barstock or Profile (shape) bar.

Cold extrusion, with the metal at ambient temperature, imparts a better surface finish and further strengthens the part via strain hardening. Cold extrusion also allows for greater geometric accuracy on smaller short lengths of a part produced by this method.

What's the difference between Direct and Indirect Extrusions?

For direct extrusion, the material is pushed through the work chamber by a ram and extruded through an outlet (Special Steel Die).

For indirect extrusion, the material is completely contained in the chamber and the outlet is built into a hollow metal ram or it forms over the ram. So as the ram pushes into the material, the profile is extruded into and through the ram itself or over the ram. This method is used a lot for tube-shaped lengths.

As with casting, the proper extrusion method for a given project is determined by the material/alloy being extruded and the dimensions and geometry of the final part.

 

 

What are the Advantages and Disadvantages of Extrusions?

PROS of EXTRUSION

CONS of EXTRUSION

Ideal for near net shape in long lengths. Used in the length, like a hand Rail or cut into short pieces to be machining into parts

Can result in surface oxidation (oxide scale) and needs to be removed by acid or mechanical methods

The near net extruded shape yield low scrap from machining the parts. This material has a very homogeneous cross-section especially for parts requiring mechanical properties & pressure tightness

If not controlled, susceptible to surface cracking, internal cracking and surface lines from bad maintained dies

Therefore, the resulting grain refinement improves the material’s impact resistance, ductility & strength

Limited part complexity

Fast & efficient for high volumes

 

What is Metal Forging?

Forging uses massive amounts of compressive force to press a solid piece of metal (billet) into the desired shape or part. Under pressure, the raw metal (billet) is forced into a custom produced special steel die that is made into the desired shape. In general, although mechanical strong, forged parts require more machining to achieve the required final part.

What are the different Forging Methods? 

A variety of forging methods exist, classified by the process temperature (cold forging or hot forging, referring to the forged metal’s temp) and the style of die used (open-die forging or closed-die forging). As with casting and extrusion, the most effective forging method for a particular project depends on the metal or alloy being forged, as well as the intended application of the final parts.

In general, forging produces parts that with excellent mechanical strength, impact strength, shear strength, and wear resistance. This is due to the high pressure the raw metal materials are put through and the resulting deformation, which causes metallurgical recrystallization and grain refinement that conforms to the part shape.

 

What are the Advantages and Disadvantages of Forging

PROS of FORGING

CONS of FORGING

Greater structural integrity & mechanical strength due to altered grain structure of materials

Difficult to meet tight tolerance requirements, unless close die forging

Less material scrap & reduced labor requirements. Close die forging can have some coring to reduce weight and costs.

Significant secondary processing may be required to achieve final design specifications on open die forging

Eliminates surface porosity & internal cavities and voids. Close die has good surface finish

Nature of the open die forging method is not conducive to complex or intricate part shapes

High reliability & consistency in ductility, strength & yields. Close die has near net shape

 

 

Contact Deeco Metals for your complete metal shop needs

Deeco Metals is your leading resource for custom architectural metal castings. Request a quote today or contact us to learn more.

The company is the world’s best forging vs casting pros and cons supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.