How to Choose Between Electric Screw Press and CNC Hydraulic Hammer?

At present, there are three main forging equipment, they are electric screw press, hot die forging press and CNC electro-hydraulic hammer. The hot die forging press is only suitable for mass production. Therefore, in the case of small batch, we usually need to choose between the electric screw press and the CNC hydraulic hammer.

Electric screw press and CNC hydraulic hammer are new products in recent years. For forging, both has its advantages and disadvantages. The selection of equipment must be based on the actual conditions of the factory, and must be combined with the production organization of the factory, the type of forgings, and the situation of the ancillary equipment. I will try to summarize this issue from several aspects for reference:

1. Production Efficiency

When we compare the production efficiency, the same forging capacity of the equipment should be put together. The forging capacity of 5 tons of CNC hammer and 2500 tons of electric screw press is roughly the same. The strike frequency of 5 ton CNC hammer forging is 50 times/minute, and it is 14 times for 2500 tons of electric screw press. In general, the production efficiency of CNC hammers is about 30% higher than that of electric screw presses.

2. The Adaptability of Different Types of Forgings

CNC hammer is universal equipment and can adapt to almost all forgings of the production, especially in the production of thin-walled, high-strength forgings. It is best choice than other equipment. The electric screw press is an equipment with high-energy and low hitting power, especially suitable for deep cavity forming of forgings.

3. Forging Capacity

The forging hammer has a strike speed of 6m/s, and the electric screw press is generally 1-1.5m/s. The high strike speed is favorable for the filling of the forgings, so the hammer has advantages as the forgings with complicated shapes.

4. Multi-Cavity Forging Capacity

 The electric screw press is powered by the screw. The forging center should not deviate from the center of the screw too much, generally used for single-cavity forging. Uneven force with two-cavity forging is not good on the screw life and its process adaptability is not as good as the hammer.

5. Universality of Equipment Process

The forging speed of the hammer is fast, and various pre-forming process such as drawing, edge rolling, bending, and upsetting can be performed, and finish forging can be performed at the same time. Therefore, the production of various parts can be almost completed on one equipment, and it is particularly suitable for production of many kinds and small batches, and there is no need for blanking equipment.

The speed of the electric screw press is slow and can only be used for pre-forging and finish forging of cavities. This equipment cannot be used for blank making. When many parts are produced, they must have blanking equipment. This also increases staffing.

6. The Surface Quality of Parts

Forging on the hammer, generally the first step is to lightly strike the scale, because the speed is very fast, and the temperature of the forging will not drop a lot. After the scale is removed, the surface quality of the forging parts is good, and the electric screw press cannot achieve this function.

7. Forging Die Life

The life of forging die is related to the following factors:

a. The wear of the scale to the forging die;

b. Contact time of forging and die;

c. Cooling and lubrication conditions.

Descaling is the first step in forging on the hammer. This process cannot be achieved by forging on the electric screw press, so the oxide scale wears heavily on the die.

When the forging hammer strikes, the contact time of the upper mold is 15-25 milliseconds, and on the press is 0.8-1 second, so the life of forging die is reduced by longer heating time on the electric screw press.

The new type of CNC electro-hydraulic hammer control strikes energy precisely, and there will not be extra energy hitting on the die. This is very different from the traditional forging hammer. On the old hammer, the die life is similar to the press, but the die life of the CNC electro-hydraulic hammer is higher.

8. The Internal Quality of the Forging

For ordinary carbon steel, the internal quality of the press and hammer forged forgings are same, but for the high carbon high alloy steel, the impact speed of hammer is faster, and the hammer is more favorable to break the mesh and band structure in the metal. After forging by hammer, the crystal structure is more uniform and the mechanical properties are better.

9. Energy Consumption

The motor power of 5 tons of CNC hammer = 2 × 132KW, the motor power of 2500 tons of press =2 × 200KW, plus the efficiency of the hammer is 30% higher than the press, so the overall energy consumption of the CNC hammer is lower

10. Environmental Factors

The problem of the vibration of the forging hammer is solved by the use of the vibration damping pad, but the noise has a large impact on the environment, so it is not environmentally friendly than the running of the press.

11. Equipment Complexity

The CNC electro-hydraulic hammer is a hydraulic device and its structure is more complex than that of an electric screw press, higher requirements for maintenance of equipment. 

12. Overload Capacity

The maximum strike force of a 5-ton hammer is 10,000 tons, and that of a 2500 press is 4,000 tons. On the hammer, as the forging with a large projected area which over the forging capacity, we can solve this by multi-strike or secondary heating, and the forging range can be doubled sometimes. The hammer is more flexible and the press cannot be achieved. Of course, this process is only used for small batch production because it is not economical.