The difference between free forging, die forging, tire die forging and roll forging

Free forging

Free forging refers to the processing method of directly applying external force to the billet between the upper and lower anvils of the forging equipment to deform the billet, so as to obtain forgings with the required geometry and internal quality. Free forging mainly produces small batches of forgings, and the blanks are formed and processed by forging equipment such as forging hammers and hydraulic presses to obtain qualified forgings. During free forging, only part of the surface of the metal is in contact with the tool or anvil, and the rest is a free deformation surface. Free forging uses general-purpose molds and tools, which has high flexibility, low cost, short production preparation period, and is suitable for single-piece and small-batch production.

However, free casting has low productivity, high labor intensity, poor precision of forgings, and large machining allowance. Therefore, the proportion of free forgings in the total forgings is decreasing with the progress of production technology. Free casting is also the main production method of large forgings, and it plays an important role in heavy metallurgical machinery, power machinery, mining machinery, crushing machinery, forging machinery, ship and locomotive manufacturing industries.

Free forging is a processing method that puts the heated metal blank between the upper and lower whetstones of the casting equipment, applies impact force or pressure, directly causes the blank to undergo plastic deformation, and then obtains the required forging. Free forging is due to the Simple in shape and flexible in operation, it is suitable for the production of single pieces, small batches and heavy forgings. Free forging is divided into manual free forging and machine free forging. The production efficiency of manual free forging is low and the labor intensity is high. It is only used for repair or simple, small, small batch production of forgings. In modern industrial production, machine free forging has become the mainstay of casting production. The primary method, which plays a particularly important role in heavy machinery manufacturing.

Advantages of free forging:

• Flexible forging, can produce small parts less than 100kg, and heavy parts over 300t;

• The tools used are simple generic tools;

• Low requirements for equipment accuracy;

• The production cycle is short.

Shortcoming:

• Low production efficiency;

• The forged shape is simple, the dimensional accuracy is low, and the surface is rough;

• High labor intensity;

Die forging

Die forging refers to a forging method in which blanks are formed on special die forging equipment using dies to obtain forgings. The forgings produced by this method are accurate in size, small in machining allowance, complex in structure and high in productivity. The heated blank is placed in a forging die fixed on the die forging equipment for forging. Die forging can be performed on a variety of equipment. In industrial production, the upper die forging of the hammer mostly adopts the steam-air hammer (Jiahangaero uses hot die forging).

Die forging on the press is commonly used for hot forging presses. The forging die structure of die forging includes single die hall forging die and multi die chamber forging die. It uses the dovetail groove and wedge to fix the forging die to prevent it from coming out and moving left and right; it uses the key and keyway to make the forging die position accurately and prevent it from moving back and forth.

Advantage:

• High production efficiency, metal deformation is carried out in the die forging process, so the desired shape can be obtained quickly;

• Forging forgings with complex shapes makes the distribution of metal streamlines more reasonable and prolongs the service life of parts;

• Die forging has accurate dimensions, good surface quality and small machining allowance;

• High material utilization rate, reducing cutting workload;

• When the batch size is large, the part cost can be reduced.

Disadvantages:

• Limited by the capacity of general die forging equipment, the weight of die forging is mostly below 70kg; (the maximum weight of Jiahangaero die forging is 50kg)

• The investment cost of die forging equipment is high.

Roll forging

Rolling forging refers to the forging process that uses a pair of relatively rotating fan-shaped dies to plastically deform the blank to obtain the required forging or forging blank.

The deformation principle of rolling forging is shown above. Rolling forging deformation is a complex three-dimensional deformation. Most of the deformed material flows in the longitudinal direction, increasing the length of the billet, and a small amount of material flows laterally, increasing the width of the billet. During rolling forging, the cross-sectional area of the billet root decreases continuously. Rolling forging is suitable for deformation processes such as shaft stretching, slab turning, and material distribution along the length direction.

Compared with ordinary die forging, roll forging has the advantages of simple equipment structure, stable production, low vibration and noise, convenient automation and high production efficiency.

Tire die forging

Tire mold forging is a forging method made by free forging, which is finally formed in a tire mold. It is a forging method between free forging and die forging. In the case of less die forging equipment, it is widely used in small and medium-sized enterprises with free forging hammers.

There are many types of tire molds for tire forging, which are commonly used in production: form molds, buckle molds, sleeve molds, cushion molds, clamping molds, etc.

Closed cylinder dies are mostly used for forging rotating body forgings. For example, there are boss gears at both ends, which are sometimes used for forging non-rotating body forgings. Closed cylinder die forging belongs to flash-free forging.

For tire mold forgings with complex shapes, it is necessary to add two half-moulds (that is, add a parting surface) to the cylinder mold to make a combined cylinder mold, and the blank is formed in the cavity composed of the two half-moulds. Composite membranes usually consist of upper and lower molds. In order to match the upper and lower dies and avoid misalignment of forgings, guide posts and guide pins are often used for positioning. Composite dies are mainly used to produce non-rotating forgings with complex shapes, such as connecting rod and fork forgings.

There are many ways of forging, and it is very important to choose the most suitable forging method for you. If you do not have your own forging equipment and need a manufacturer to assist you, Jiahangaero is a good choice, we can provide to you professional forging service. We have 16 sets of forging equipment, including the most advanced hot die forging equipment, and roll forging equipment. The maximum forging size can reach 1000mm, the weight can reach 50kg, and the annual output can reach 4-6 million pieces. Welcome to contact us for a real-time quotation.