Is there a difference between a flat forging machine and a hot forging machine

A forging method that causes plastic deformation of metal billets in a mold under the action of external forces and fills the mold cavity (mold cavity) to obtain the required 

shape and size of forgings. Most metals are forged in the hot state, so die forging is also known as hot die forging. Compared with free forging, die forging can produce 

forgings with more complex shapes and more accurate dimensions, with higher production efficiency. It can produce a large number of forgings with basically the same 

shape and size, which is convenient for the subsequent cutting process to use automatic machine tools and production lines. After forging, a directional fiber structure, 

namely streamline, is formed inside the forging. Selecting a reasonable forging process and mold to ensure that the distribution of flow lines is consistent with the shape 

of the parts can significantly improve the mechanical properties of the forgings. But forging requires specialized molds, which must be made of high-quality alloy tool 

steel. The shape of the mold chamber is complex, requiring high precision, large processing volume, long production cycle, and expensive price. Therefore, die forging 

is generally suitable for large-scale production, or for situations where although the batch size is not large, there are high requirements for the shape and performance 

of forgings.

The precision of die forgings is high, and the decision of machining allowance needs to consider the manufacturing accuracy of the mold and its wear during use, cold 

shrinkage and surface oxidation of the metal, metal flow and filling state, the slope, fillet and forging deviation required for forging, and the allowance required for c-

utting processing. In actual production, the machining allowance for forgings is selected according to standards. One of the development directions of modern die 

forging technology is to use special precision forging processes, strictly control the local tolerances of forgings, leave no machining allowance, and no longer cut.

Die forging is usually divided into hammer forging, hot die forging, screw press forging, hydraulic press forging, flat forging machine forging, and electric heating 

forging according to the equipment used.

Hammer forging is widely used in production. The forging die is divided into upper and lower parts, which are fixed on the hammer head and anvil seat of the die forging 

hammer. The forging is formed by striking the lower die on the anvil seat with the upper die on the hammer head (a die forging hammer without an anvil seat is struck by 

the upper and lower anvils). The billet often goes through several billet making processes, and therefore, there are corresponding multiple die chambers on the forging die. 

When forging, the billet is first heated to the initial forging temperature (see forging billet heating), and then manually moved into the corresponding die chamber according 

to the process, subjected to successive blows by the forging hammer, and finally formed in the final forging die chamber. A typical hammer forging goes through 6 processes。

① Upsetting: used to reduce the height of the billet and increase the cross-sectional area.

② Elongation: Flip the billet around the axis and feed it along the axis to reduce the local cross-section of the billet and extend its length.

③ Rolling: During operation, only flipping without feeding can increase the aggregation of local cross-sections of the billet and make the surface of the entire billet smooth 

and round.

④ Bending: used to change the shape of the billet axis.

⑤ Pre forging: Improve the forming conditions of forgings and reduce the wear of the final forging die chamber.

⑥ Final forging: To shape the forging and determine its shape and accuracy. There are flash grooves around the final forging die chamber.

The striking speed of the forging hammer is fast, the striking energy is large, and the weight of the striking can be freely controlled by the operator, so it has good 

adaptability to forgings. It can forge various complex shaped forgings from less than 1 kilogram to about 200 kilograms, such as engine connecting rods, crankshafts, 

automotive universal joints, front beams, and various gears. Hammer forging has high productivity and low equipment investment. The disadvantages are high vibration 

and noise, difficulty in mastering operating techniques, poor working conditions for workers, and high labor intensity. In addition, forging hammers generally do not have 

ejection devices, and forgings require a larger forging angle, resulting in a lower lifespan of the mold.

Hot forging press is generally a crank type mechanical press. Its vibration and noise are smaller than those of hammer forging, and the operating technology is also 

relatively easy to master. It has high productivity and is easy to use mechanical arms to achieve automated production. The hot die forging press has good rigidity, high 

slide guide accuracy, and a forging ejection device, which can use a smaller forging slope. The second automobile manufacturing plant in China mainly produces 120000 kilonewton hot die forging presses, equipped with automatic forging production lines such as roll forging machines, edge cutting presses, twisting machines, straightening 

presses, robotic arms, and conveyor devices. It can forge 60-90 car crankshafts or front beams per hour. The stroke of a hot forging press is fixed and cannot replace a roll 

forging machine or other equipment to complete the corresponding blank making operation, nor can it use the impact inertia to form forgings like a forging hammer. In 

order to fill the die chamber with forgings, it is often necessary to increase the number of pre forgings, so that the billet gradually approaches the shape of the forging in 

several die chambers, resulting in a more complex structure of the mold. Hot die forging press is suitable for mass production.