• Forging

Forging Parts

What is forging?

Forging is a kind of pressure of forging machinery for metal blank, make its produce plastic deformation for mechanical properties of a certain shape and size of forging processing method, forging, forging and stamping) through one of two major parts of forging can eliminate the metal smelting process of as-cast loose defects, such as optimizing the microstructure, at the same time because of the intact metal flow, forging generally better than that of the same material on the mechanical properties of the casting high load working conditions in the severe important related machinery parts, in addition to the shape of a simple rolling outside plank material or components are available, and more using forgings

Forging defined

At its most basic level, forging is the process of forming and shaping metals through the use of hammering, pressing or rolling. The process begins with starting stock, usually a rolling round steel , which is heated to its plastic deformation temperature, then upset or “kneaded” between dies to the desired shape and size.

During this hot forging process, the rolling steel, coarse grain structure is broken up and replaced by finer grains. Shrinkage and gas porosity inherent in the cast metal are consolidated through the reduction of the ingot, achieving sound centers and structural integrity. Mechanical properties are therefore improved through reduction of cast structure, voids and segregation. Forging also provides means for aligning the grain flow to best obtain desired directional strengths. Secondary processing, such as heat treating, can also be used to further refine the part.

Forging can create a myriad of sizes and shapes with enhanced properties when compared to castings or assemblies.

Development of metal forging technology

When buyers must select a process and supplier for the production of a critical metal component, they face an enormous array of possible alternatives. Many metalworking processes are now available, each offering a unique set of capabilities, costs and advantages. The forging process is ideally suited to many part applications; however, some buyers may be unaware of the exclusive benefits available only from this form of metal forming. In fact, forging is often the optimum process, in terms of both part quality and cost, especially for applications that require maximum part strength, custom sizes or critical performance specifications.

To meet the changing needs of industry, forging has evolved to incorporate the tremendous advances in equipment, robotics, computers and electronic controls that have occurred in recent years. These sophisticated tools complement the creative human skills which, even today, are essential to the success of every metal forging made. Modern forging plants are capable of producing superior-quality metal parts in a virtually limitless array of sizes, shapes, materials and finishes.

Forging process introduction and process advantages

Forging process introduction

Closed die forging pounds or presses metal between two dies (called tooling) that contain a precut profile of the desired part. Parts from a few ounces to 60,000 lbs. can be made using this process. Some of the smaller parts are actually forged cold.
Commonly referred to as closed-die forging, impression-die forging of steel, aluminum, titanium and other alloys can produce an almost limitless variety of 3-D shapes that range in weight from mere ounces up to more than 25 tons. Impression-die forgings are routinely produced on hydraulic presses, mechanical presses and hammers, with capacities up to 50,000 tons, 20,000 tons and 50,000 lbs. respectively.
As the name implies, two or more dies containing impressions of the part shape are brought together as forging stock undergoes plastic deformation. Because metal flow is restricted by the die contours, this process can yield more complex shapes and closer tolerances than open-die forging processes. Additional flexibility in forming both symmetrical and non- symmetrical shapes comes from various preforming operations (sometimes bending) prior to forging in finisher dies.
Part geometry’s range from some of the easiest to forge simple spherical shapes, block-like rectangular solids, and disc-like configurations to the most intricate components with thin and long sections that incorporate thin webs and relatively high vertical projections like ribs and bosses. Although many parts are generally symmetrical, others incorporate all sorts of design elements (flanges, protrusions, holes, cavities, pockets, etc.) that combine to make the forging very non-symmetrical. In addition, parts can be bent or curved in one or several planes, whether they are basically longitudinal, equidimensional or flat.
Most engineering metals and alloys can be forged via conventional impression-die processes, among them: carbon and alloy steels, tool steels, and stainless, aluminum and copper alloys, and certain titanium alloys. Strain-rate and temperature-sensitive materials (magnesium, highly alloyed nickel-based superalloys, refractory alloys and some titanium alloys) may require more sophisticated forging processes and/or special equipment for forging in impression dies.

Advantages of Closed Die Forging

1.What is Closed Die Forging?

Closed die forging, also known as impression die forging, is one of the forging types for small or medium metal components. Close die forging is a plastic deformation process where, unlike in the open die forging process, the material is forced to flow in a closed shape called die. Compared to the open die forging, the close die forging (said also hot drop forging) can achieve more complex geometries, very much close to the dimensions of the finished component. The plastic deformation is given rapidly through some shots which force the material to fill the shape of the die. The process is performed at the plastic temperature of the material in use without intermediate re-heatings.

A key step in closed die forging is the design and the production of the dies, process which is part of the know-how of the manufacturer. Most common used forging dies material are tool steels. For the high material cost and machining cost, cost of forging dies are always much higher, but it is one time cost, will not be charged from our customers for next batch production. Unlike the open die forging, suitable to manufacture also individual parts, the close die forging is used to manufacture series production as this is particularly convenient to absorb the costs the dies. The close die forged product shows several advantages like the typical flow lines of the material along the profile of the component, beneficial particularly on mechanical components put in service under cyclic fatigue. This process allows furthermore to use reduced over-dimensions, feature which allows cost savings on input weights as well as on final machining due to less material to remove. The close die forging process is typically used for critical components, in our case on railway, petrochemical, electrical, lifting and safety system, industrial and agricultural machinery sectors.

2.Closed Die Forging Process

Closed die forging is the process that metal is placed in a die resembling a mold attached to an anvil. Usually the hammer die is shaped as well. The hammer is then dropped on the workpiece causing the metal to flow and fill the die cavities. The hammer makes contact repeatedly within milliseconds. Depending on the size and complexity of the part the hammer may drop multiple times in a series of quick successions. The excess metal that is squeezed out of the die cavities is referred to as flashing. The flash cools more rapidly than the rest of the material and the flash is usually stronger than the metal in the die so it helps prevent more flash from forming. The flash also forces the metal to completely fill the die cavity and after forging the flash is removed.

In commercial closed die forging, the workpiece is usually moved through a series of cavities in a die to get from ingot form to the final form. The first impression is used to distribute the metal into the rough shape in accordance to the material needed later in the cavities. This impression is called an edging or fullering or bending impression. The cavities after this are called blocking cavities in which the piece is worked into a shape that more closely looks like the final product. These different stages usually give the workpiece generous bends and large fillets. The final shape is forged in a finisher or final cavity. If there is only a short run of the parts then it may be more economical to forgo the final impression cavity and instead machine the part.

3.Common Materials in Closed Die Forging

 While closed die forging is applied for almost all the metal materials, in actual production, only part of the materials are used for the different characteristics. The material used is one of the main factors that affect the cost of the forgings. Let’s take a look at some of the common materials used in closed die forgings.


When it comes to closed die forging, steel is by far the most common material used. Alloy steel, carbon steel, and stainless steel are all used depending on what the forging is used for. Stainless steel material is often used for components that require corrosion resistance and rust resistance. Alloy steel and carbon steel are the most widely used in closed die forging process for its competitive price and easy deformation.


Aluminum is popular due to its low density, high strength, and easy machining. It is widely used in closed die forging process especially for the automotive and aerospace industries. Although it is commonly used in the aerospace and automotive industries, it is a challenge for domestic forging due to the fact that it is easily deformed after forging.But heat treatment can help to improve the hardness and other properties.

Copper or Brass

Copper or brass is also commonly used in closed die forging, which is the most expensive of the three materials that we have discussed. Copper forging or brass forging is most commonly used for valve and pump fittings.

Benefits of Closed Die Forging

Distinct from investment casting, initial costs of forging dies for developing a metal components in closed die forging is quite high, but by comparison, if the parts are in high volume, it is the most cost-effective metal forming methods for the low cost of each part.
During closed die forging process, the pressing of workpiece between forging dies will refine the inner grain, and the mechanical properties of closed die forged parts, especially the strength, will be improved. So, when safety factor and strength is considered, like lifting & rigging hardware, closed die forging will be the unique choice.
As products are deformed in high precision forging dies, so the toleraces of closed die forging parts are always tight. And surface finish is always good. Normally, we can control closed die forging parts within tolerance +/- 0.5mm. In this way,this forging technic is a net or near net shape process that requires less or no machining. So for same parts made in forging and casting, there will be aobvious advantages of closed die forging for its less machining cost.
Material is saved. If you learn about closed die forging, then you will know the only waste of material during forging process is the flash. Such flash will be moved by trimming die, and you will be a finished forging blank after that. Thus we can see the flash is the only redundant material, but it can be recycled.
Closed die forging service in China can offer more price advantage as well as other advantages.
Materials of closed die forging are not limited, it can be steel, aluminum, brass, ect. Although there are lots of benefits in closed die forging, it does not mean it can be used to make all the metal components, for thin and complex shaped components, it is not feasible. So each metal forming process has its own limitations.

Closed Die Forging vs Open Die Forging

In open die forging a cylindrical billet is subjected to upsetting between a pair of flat dies or platens. Under frictionless homogeneous deformation, the height of the cylinder is reduced and its diameter is increased. Forging of shafts, disks, rings etc are performed using open die forging technique. Square cast ingots are converted into round shape by this process.

Closed die forging is a precision forging process for its precise tooling or dies, while open die forging is free forging with simple tooling. So closed die forging can provide much more precision components, specially for small and medium parts. And open die forging is only for large products.

Closed Die Forging vs Investment Casting

Different from closed die forging, investment casting is the casting method by pouring liquid metal into molds to form the shapes. The same point of these two methods is that both of investment casting and closed die forging can manufacture components in accurate dimensions and tolerances. But defects may be easily produced by investment casting, which could be effectively avoided in closed die forging.

Another advantage of closed die forging is that, the pressing operation of billets will greatly increase the strength of products. So closed die forging is especially suitable for components in safety consideration, such as lifting & rigging hardwares.

Closed Die Forging vs Machining

For simple shaped parts, machining from bars directly is also the option for desired dimensions.

Compared with closed die forging, there will exsit large amounts waste of raw material.

Also, the properties and working performance of closed die forged components will be much better than machined ones.

Closed Die Forging Application

Closed die forging is mainly used for the production of steel and aluminum components. So the application of closed die forging is wide. It coud be used forAutomobile industry, electric power industry, railway locomotive, petrochemical industry,the production of mining drilling bits, forestry wear parts, agricultural wear parts, construction wear parts, rigging and lifting components, ect. In a word, Any application requires high quality components could adopt this type of method.

Professional closed die forging factory business and services

Henan gold emperor industrial technology co., LTD. Main business is industrial parts, auto parts design product design production, other mechanical parts design and manufacture, r&d and production of titanium alloy materials and its products, tungsten alloy, molybdenum alloy products research and development production, the company has a complete mechanical parts design form a complete set of production technology process, is a professional mechanical parts suppliers.
The factory is well equipped to produce products from 0.1kg to 200kg.The factory is equipped with 30 machining centers, which can guarantee the subsequent machining process of batch products.We can produce many kinds of products: carbon steel forgings, alloy steel forgings, copper forgings, aluminum forgings, stainless steel forgings, titanium alloy forgings, tungsten molybdenum alloy forgings, etc.Our products are mainly used in automobile industry, engineering machinery industry, railway locomotive industry, electric power industry, petrochemical industry, mining machinery and other industries.
The quality control equipment of the company includes flaw detector, hardness tester, spectrometer, metallographic analysis, impact testing machine, tensile test, coordinate measuring instrument, etc., which can effectively control the quality of each product.The company is engaged in industrial parts product design and production for 20 years, has accumulated rich industry experience, has many senior technical engineers.The company undertakes customized OEM services for processing of incoming drawings and samples, and can complete all processes including 3d modeling design, mold design and production, product forging and pressing, heat treatment of forgings, and machining.Our company has set up an independent industrial design service center, has a professional industrial design service team, can provide customers with professional product technical services.

Gold emperor forging proces

Different forging methods have different processes, among which the process of hot die forging is the longest, and the general order is: forging blank blanking;Forging billet heating;Roll forging blank;Forming by die forging;Trimming;Punching;Correction;Intermediate inspection, inspection forgings size and surface defects;Heat treatment of forgings to eliminate forging stress and improve metal cutting performance;Cleaning, mainly removing the surface oxide scale;Correction;Inspection, general forgings to go through the appearance and hardness inspection, important forgings have to go through the chemical composition analysis, mechanical properties, residual stress and other tests and non-destructive inspection.

Closed die Forging Process

we will introduce steel forging process under closed die forging technology in detail. Normally, main steps of closed die steel forging processes are die/tool making, billet cutting, billet heating, forging, trimming, heat treatment, shot blasting, machining, surface treatment, inspection and package.

Step 1. Die design & making

Dies making is the unnecessary step for close die steel forging parts. Once a new order is placed, our engineer will design dies according to steel forging drawing from customers. Unlike casting,steel forging dies will include forging dies, trimming dies and flatten dies, that is why forging dies are much expensive than casting molds.

Step 2. Billet cutting & heating

In our forging company, we will keep some common steel material specifications in stock for continious production. After dies are completed, steel billets will be taken from our material warehouse, then cut into required length and heated by medium frequency furnace before forging.

Step 3. Closed Die Forging

After heating billets, heated steel bars will be placed under upper and lower dies, and then pressed into desire shape, but redundant material will shown around the product, which is named as flash.

Step 4. Trimming

Now forging blanks with flash are obtained, to remove the flash, the forged steel blanks will be put under trimming dies and pressed again. In this step, a whole forging blank is finished.

Step 5. Heat Treatment

In order to improve the strength and mechanical properties of forged products, eliminate the internal stress caused by forging and improve the internal structure of forged products, It is necessary to heat the forgings after they are forged, common heat treatment methods for steel forgings are normalizing, quenching, annealing, tempering & hardening, solution treatment,ect. Of course,heat treatment is only operated when it is required.

Step 6. Shot Blasting

In order to remove the oxide scale caused by high temperature oxidation in the forging process, as well as some small burrs in the forging process, to achieve better surface finish, the steel forgings will be shot blasted.After peening treatment, the product appearance is more clear and smooth.

Step 7. Machining

Many forgings are used in precision machinery and some key assembly positions, which require the size of some workpieces to have ultra-high precision. At this time, it is necessary to cooperate with machining equipment to process the forgings and meet the requirements of product assembly and use.

Step 8. Surface Treatment

If there is no special surface treatment requirement, water/oil anti-rust painting is enough before package. Sometimes special surface treatments are also required according to the application of steel forgings, likeZinc plating, electrophoresis, blackening oxidation, electrostatic spraying , ect.

Step 9. Inspection

Inspection is also an important step. We can divide inspection process into external inspection and internal inspection. External inspection includes: dimention testing,visual defects inspection. And internal inspection refers to internal properties inspection.

Step 10. Package & delivery

Forgings for export are packed in plastic bags in strong fumigation-free wooden cases to protect them from damage during long transit.In addition, we can also customize packaging according to the special requirements of customers.