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Stamping, forging and spinning are commonly used metal parts machining processes. Do you know the similarities and differences between them?

The Define Of Stamping,Forging And Spinning

Metal spinning/metal stamping/metal forging is a process used by manufacturers to process axisymmetric metal parts. This process is efficient and versatile. In China, our partner Be-cu.com has provided customers in aerospace, commercial, medical and defense industries with more than 30 years of high-quality metal manufacturing services.

What Is Metal Stamping

Stamping is a processing method with high efficiency, low consumption and low technical requirements. Stamping parts are not only used in large-scale manufacturing. If you pay attention, you will find that there are many stamping parts around us (for example, 80% of the parts in watches are stamping parts). Even if you have not learned the knowledge of stamping, give you some stamping parts, you will find several obvious characteristics:

• (1) Most stamping parts are thin sheets or layered sheets (plates or profiles, pipes, etc.);
• (2) The vast majority of multi stamping parts are formed at one time without any trace of secondary processing
• (3) They are all metal pieces

In fact, from a professional point of view, the stamping process is a processing process to separate the raw material sheet according to a certain shape and generate metal molding(Include laser cutting and sheet metal fabrication) deformation to obtain the desired shape through the stamping die and stamping equipment. For a specific die, the shape, size and performance of the stamping parts are basically consistent.

• Stamping Mold:Generally speaking, the stamping die is the “template” used for stamping. One template can only punch one type of stamping parts. Different types of stamping dies need to be selected according to the different sizes, materials and shapes of the required stamping parts
• Stamping Equipment: Stamping equipment is actually the so-called press. Stamping is the forming process method of workpieces (stamping parts) with required shape and size by exerting external force on plates, strips, pipes and profiles to cause plastic deformation or separation. It can be imagined that the force required for stamping cannot be achieved without the pressure of large machinery, which requires a press. There are also many kinds of presses. The most common one is hydraulic press: a machine that uses hydrostatic pressure to process metal, plastic, rubber, wood, powder and other products. It is commonly used in pressing process and pressing forming process, such as forging, stamping, cold extrusion, straightening, bending, flanging, sheet drawing, powder metallurgy, press fitting, etc. Hydraulic press is divided into hydraulic press and hydraulic press.

What Is Metal Forging

Forging has a long history in China, which has been continued by the way of manual workshop production. Probably at the beginning of the 20th century. It gradually appeared in the railway, military, shipbuilding and other industries in the way of mechanical industrialization. The main sign of this transformation is the use of machines with strong forging ability.

Metal Forging is widely used in automobile manufacturing. With the progress of science and technology, the requirements for workpiece accuracy are constantly improved, and precision forging technology, which has the advantages of high efficiency, low cost, low energy consumption and high quality, is more and more widely used. According to the different deformation temperatures during metal plastic forming, precision cold forging can be divided into cold forging forming, temperature forming, sub hot forging forming, hot precision forging forming, etc. The automobile parts produced include: automobile clutch engagement ring, input shaft parts of automobile transmission, bearing ring, sliding sleeve series of automobile constant velocity universal joint, automobile differential gear, automobile front axle, etc.

Forging is a processing method that uses forging machinery to exert pressure on metal blank to make it produce plastic deformation to obtain forgings with certain mechanical properties, certain shapes and sizes. Forging (forging and stamping) is one of the two major components.

Forging can eliminate as cast porosity and other defects produced in the smelting process of metal, optimize the microstructure. At the same time, due to the preservation of complete metal streamline, the mechanical properties of forgings are generally superior to castings of the same material. For important parts with high load and severe working conditions in related machinery, forgings are mostly used, except for simple rolled plates, profiles or weldments.

What Is Metal Spinning

Speaking of ceramic art, I believe that everyone will have such a scene in mind: holding a ball of mud with both hands, during the rotation of the machine, through the stretching or squeezing of both hands, the mud gradually becomes a variety of ceramics. Did you know that hard metals can also be made into various products through similar processes. This miraculous process is called “spinning”.

Metal Spinning is to fix the flat plate or hollow blank on the die of the spinning machine. When the blank rotates with the main shaft of the machine, it is pressed on the blank with a spinning wheel or a driving rod to cause local plastic deformation. Spinning is a special method of sheet metal forming, which can complete complex geometric features of various complex sheet metal parts. The spinning method can be used to complete the geometric features of complex sheet metal parts such as drawing, flanging, necking, bulging and crimping.Stamping VS Forging VS Spinning,What is their common point and differences?

Common Points Of Stamping, Forging And Spinning

The principle is that the press exerts pressure on the metal in the mold, and the efficiency is very high, and the processing speed can be very fast; They all need molds. Generally, molds are expensive to process, but once they are successfully processed, they can be mass produced.

The technical requirements are high. Generally, master die technology is required, which requires greater investment. Forging requires greater investment.

Most of the processing machines are mechanical or hydraulic presses. The layman looks similar and has many similarities, but there are many differences in equipment structure and practical application.

It is a kind of processing technology. It does not produce its own independent products. Stamping, forging and spinning provide several or even hundreds of products for downstream users. They are only a small link in the middle of the industrial chain, subject to downstream demand, and generally do not have pricing power.

Differences Between Stamping, Forging And Spinning

Stamping is basically cold processing, of course, there is also hot stamping, but less; Forging is basically hot, which requires heating the processing materials and cold forming, but heat treatment is required after the completion; Spinning generally focuses on cold processing, but during the processing, the material itself will become hot.

Forging is volume deformation, metal structure change, and processing is basically three-dimensional stress parts, such as the crankshaft and connecting rod in the engine; Stamping is the deformation of sheet metal. Generally, it does not involve the change of internal crystals. It is just the stretching deformation of the thickness of sheet metal. The processed stampings are either stressed or not, and have a wide range of applications; Spinning has the deformation mode of stamping and forging, which can not only change the volume (shape) of the material, but also change the thickness of the material through stretching.

The working environment of the forging workshop is relatively harsh and messy, accompanied by huge noise, as well as the smell of burning in the heating industrial furnace, cooling graphite, oxide scale and other smells; The stamping workshop is relatively good, but due to the up and down collision of the stamping machine, the noise is not small; The aluminum/brass/copper spinning workshop environment is relatively good. The spinning machines are basically equipped with protective doors, which can isolate part of the noise, and there is little or no waste generated.

From the perspective of workers, traditional factories are very boring, stamping automation is very common, forging is relatively difficult, spinning mostly depends on China CNC machining technology, and the requirements for workers are not very high.

No matter what kind of processing technology, it belongs to the manufacturing industry. Manufacturing industry is an essential and important basic industry, which is related to people’s livelihood. Therefore, we should make full use of the characteristics and advantages of each process to manufacture products with high requirements and improve the overall industrial capacity of the country.

Link From:Beryllium Copper China

What Is Die Casting?Die Casting and it is a precision casting method that obtains the same casting as the mold by injecting molten metal into a steel mold that is precisely machined to perfectly match the required casting shape. In addition to the advantages of almost no need for finishing as the dimensions are accurate, it has excellent mechanical properties and is capable of mass production.Die casting is also called pressure die casting. It is a precision casting method in which molten metal is injected into a steel mold that is precisely machined to perfectly match the required casting shape to obtain a casting identical to that of the mold. The product is called die-casting parts.

In addition to the advantage that there is little need for finishing because the dimensions are accurate, it has excellent mechanical properties and can be mass-produced. The metal used is an alloy such as zinc, aluminum, tin, copper, and magnesium, and it is cooled and solidified by injecting it by air pressure, water pressure, or hydraulic pressure using a die-casting machine.

There are many automobile parts as products, including parts for electrical equipment, optical equipment, vehicles, weaving equipment, construction equipment, and measuring instruments.

The Definition And Terminology Of Die Casting

Die casting is defined as “a casting method that mass-produces castings with excellent casting surfaces with high precision by pouring molten metal into a precision mold and products resulting from it”. In Japanese, the word “die casting” is also used, but American die casting is adopted. In the UK, mold casting is called gravity die casting, low pressure casting is called low pressure die casting, and die casting is called pressure die casting.

The Characteristics Of Die Casting

The main advantages and disadvantages of die casting are as follows.

“Advantages”

• Products with complex shapes can be mass-produced in one process.
• Because it is high-speed and high-pressure filling, there is no molten metal vortex and the dimensional accuracy of the casting state is good.
• Because it is a high-speed and high-pressure filling, the hot water flow is good, a thin product can be made, and the casting surface is beautiful.
• The productivity per hour is good because it is fast charging and rapid cooling and solidification.
• Mechanical properties are improved by the formation of a seven-layer by rapid cooling.

“Disadvantage”

• Coping with pores caused by the inflow of air or gas.
• Solution treatment or welding cannot be performed due to the inflow of air or gas.
• Since the mold is expensive, economical mass production cannot be secured.

Die Casting Machine

Because the sleeve and flanger are not in the molten metal and are not heated, it is called a gold chamber.On the other hand, a machine called a hot chamber is used for die casting of zinc or magnesium and is not used for aluminum alloy. Cold chamber die casting machines in Japan have a minimum clamping force of 0.5MN and a maximum of 40MN. The injection force is 1/10 to 10/20 of the clamp force.

Die Casting Cycle

One cycle of aluminum alloy die casting by cold chamber machine will be described.

• a) Close the two molds by matching the movable mold to the fixed mold by the machine’s mold clamping operation. With a ladle, molten aluminum alloy is poured into a sleeve called a cold chamber.
• b) The plunger operates and presses the molten metal into the mold cavity at high speed and high pressure. The mold is water cooled to prevent overheating.
• c) When the molten metal solidifies, open the mold and return the flanger and the moving core to their original state.
• d) Operate the extrusion pin to push the product out of the die casting molds.

The size of the machine used depends on the size of the die-casting product. One cycle of die casting takes several seconds for small size and several minutes for large size. In recent die casting production, some factories are aiming to automate their operations and unmanned them.

Casting pressure, which is a typical casting condition item of aluminum die casting, is in the range of 10 to 200 MPa, and the gate speed is in the range of 2 to 100 m/s. The casting conditions of die casting are quite different from those of gravity casting.

Features are as follows

• Cast with high pressure
• Cast at high speed. Therefore, the filling time into the mold is very short
• In the mold, the filled molten metal is rapidly cooled and solidified.

Die Casting Manufacturing Process

Die casting work performed in most factories is supported by automatic hot water supply device, plunger lubrication device, automatic spraying device, product dispensing device, etc., and is being mechanized and systemized. Fully automatic operation and unmanned operation are also being realized. The trimming device mainly relies on the knitting press operation, but sand blasting or shot blasting are also used in combination. In post-processing, machining and surface treatment are performed. For the surface treatment, buffing, chemical conversion, painting, anodizing, plating, and the like can be selected.

Dimensional Tolerance Of Die Casting

It goes without saying that the dimensional accuracy required for a product is after final processing, and errors in material and processing are added.

The dimensional tolerance of the typical aluminum alloy die-casting ADC12 in the as-cast state can be interpreted as follows.

• Dimensional tolerance = casting tolerance + mold tolerance + shrinkage vs. calculation tolerance + tolerance for casting operation
• Calculation formula for maximum possible dimensional tolerance – ε=±0.75×10-³×L。(mm)
• Calculation formula for precise dimension tolerance – ε=±(1.15×10-³×L。+0.1) (mm)
• Calculation formula for general dimensional tolerance – ε=±(2.15×10-³×L。+0.2) (mm)

In this case, L. is the length of the mold cavity at room temperature, and ε is the dimensional difference of the die casting. The factor that fluctuates the casting tolerance is the mold temperature difference.As a standard for dimensional tolerance, there is JIS B 0409 die casting normal tolerance, and the normal tolerance of length and the maximum value of degradation angle are determined.Japan Die Casting Association standardized the details again and indicated length tolerance, angle tolerance, flatness tolerance, and eccentricity tolerance.

The Mechanical Properties Of Die Casting

The mechanical properties of die casting show the measured values ​​of the simple shape individual molten metal injection test pieces and the measured values ​​of the test pieces cut from mass-produced products. In general, the former is larger than the latter. ASTM test pieces are distributed as individual molten metal injection test pieces.

The strength of die casting cannot be guaranteed as a substitute characteristic. Apply a load corresponding to the actual and practical load to the die casting to destroy it, and obtain a numerical value that can be statistically guaranteed to withstand the load, for example, the lower limit of 3σ.

Die Casting Defects And Countermeasures

The extent to which defects are allowed depends on the required quality of the product, so the limit should be clearly defined when trading.

(G) Japan Die Casting Association has suggested casting surface standards and foam standards. There is also a new defect name called Fracture Layer. It is explained that the solidified layer generated in the injection sleeve of die casting is an abnormal tissue that is broken by the flanger and flows into the molten metal into the cavity. The strength of the interface between the fractured layer and the normal tissue is significantly lower than the strength of the normal tissue as it is inserted at less than 9kgf/mm². This is the cause of extremely lowering the strength of the die casting. According to the degree of demand for the strength of die casting, the development of a method for preventing the occurrence of a fracture layer is in progress. Methods to increase the heat retention of the molten metal in the sleeve just before injection, such as the ceramic sleeve method and the powder lubrication method, are being sought.

New Die Casting Method

Die casting has been quantitatively expanded by using high productivity and good flow of hot water for thin products as sales points. However, the high-speed charging that realizes it, on the one hand, cannot avoid air bubbles due to mixing.

may be the cause Several new die casting methods have been developed in response to product design requirements such as filling, airtightness, and strength leveling as castings, and heat treatment or welding.

(1) Vacuum Method

The history of vacuum method is quite old. Methods currently industrially known include the GF method, the mass vent method, the shutter-off pin method, the RSV method, the superback method, the MFT method, and the VACURAL method. The vacuum method widely used in Japan is the GF method.

(2) PF Method

Also called non-porous die casting. The principle is to eliminate air bubbles by purging the mold cavity and sleeve with oxygen, mixing oxygen with the molten metal in the spray state by high-speed injection, and fixing oxygen with Al₂O₃. Die casting made by PF method can be solution heat treated and artificial aging heat treated. Sometimes welding.

(3) Local Pressure Method

After filling the mold cavity with the molten metal, a local pressure higher than the casting pressure is applied to the molten metal or the reaction solid in the cavity by pressing a pressure pin by a predetermined stroke. There is an effect of filling the voids of the decrease in the cavity volume caused by such pressurization. It is effective as a countermeasure against air bubbles in the thick part isolated in the part away from the gate.

(4) Hot Chamber Method

The hot chamber machine method is named because the injection mechanism is immersed in the molten metal. Since the steel injection mechanism part is easily eroded by the molten aluminum alloy, a hot chamber machine is usually not used for aluminum alloy die casting. However, if this method can be applied with high productivity, high level of automation, and stability of molten metal quality, new demand development can be expected for aluminum alloy die casting. In 1987, the Small and Medium Business Corporation tested a hot chamber die casting machine with a clamping force of 2.5MN. Ceramic materials such as silicon nitride are used for parts in contact with molten aluminum alloy. As a result of the operation test, improvement in quality, slimming, productivity improvement, and energy saving can be expected.

(5) Collapsible Core Method

One of the disadvantages of die casting is the restriction on the undercut shape. One of the solutions is to use a metal neutralizer setting. Another method, which is a collapsible reactor, uses salt or silica sand as an aggregate.

The Development Of Die Casting

The global aluminum die-casting market is expected to show continuous growth in accordance with the trend toward lighter weight of parts used in the automotive and aerospace fields.

Grand View Research’s ‘Global Aluminum Die Casting Market’ report that contains such content forecasts that it will grow at a CAGR of 5.1% from 2021 to 2028, reaching $35.64 billion in 2028.

Aluminum die casting is a process of injecting molten aluminum by applying pressure to a mold, and is divided into pressure die casting and other processes depending on the production process.

According to the report, high pressure die casting manufacturer (HPDC) in the production process sector accounted for the largest revenue share in 2020 and this trend is expected to continue through 2028. This is explained by the high preference for HPDC among casting manufacturers due to the high efficiency of the process.

It also points out that increasing demand for aluminum die casting or zinc die casting products is intensifying competition in the market, leading market players to gain a competitive edge through strategic initiatives such as mergers and acquisitions (M&A) and increased production capacity and to gain a competitive edge in losses from the impact of COVID-19. expected to recover.