Cold forging vs. Hot forging:

Cold forging vs. Hot forging: explanations, pros, and cons(kallstukning)

Cold forging vs. Hot forging: explanations, pros, and cons
The cold forging manufacturing method

The advantages of cold forging 

The disadvantages of cold forging

The hot forging process for manufacturing

The advantages of hot forging

The disadvantages of hot forging

The cost factor

 The profitability of the blacksmith cold

 The profitability of the hot forging

Main difference between hot forging and cold for
The forging is a method of making wherein a metal part in the solid phase is formed by application of pressure forces. According to the temperature at which it is performed, the forging process is called " hot ", " mi-hot " or " cold ". The machines used to compress and deform the high strength material pieces can be classified into the following categories:

Machines punching : hammer forging, presses, screw, axial forging and incremental
Press translation movement: mechanical and hydraulic presses
Press rotary motion: longitudinal and radial rolling mills
Set of presses with movements of translation and rotation: orbit forging and spinning
 
granular structure forged components
It is essential to note that the forging manufacturing method differs from the casting which comprises pouring the molten material into a mold. This technique differs from other manufacturing methods such as casting and machining capacity of the forge to improve the mechanical properties of the material by refining its granular structure and providing the right angle orientation to the grain, making it more solid and resistant.

The cold forging manufacturing method
The cold forging manufacturing method is performed at room temperature. The workpiece is pressed between two dies until it has taken shape. To obtain a loan finished component mounting, several techniques are used, such as rolling, drawing, stamping, spinning, extrusion and discharge end. Cold extrusion is one of the most common manufacturing techniques, and is widely used for the production of components car .

cold forged components

The advantages of cold forging
Some manufacturers prefer the cold forging process than hot forging as forgings Cold require little or no finishing work. Indeed, a secondary heat treatment before machining is unnecessary since all the bars are annealed before being forged. The cold forging allows the manufacture of forms close to their final dimensions, which allows a saving in materials. The initial weight of the workpiece is equal to the final weight of the forging cold, which is another important advantage. Finally, cold forgings offer a good level of achievable dimensional accuracy and excellent surface quality.

The economic benefits associated with high production rates and long matrix of life are more than enough to convince many manufacturers that cold forging is the solution that suits them best.

The disadvantages of cold forging
According to the manufacturer's requirements, some cold forging characteristics can prove to be disadvantages. For example, at high volume, it is not possible to produce as simple shapes. The achievable strain levels and formatting quality are much more limited compared to stamping. Thus, if the client is looking for a specific and custom component, forging cold will not be the best choice for him.

The second major disadvantage is that the cold-forged metal less ductile, which makes them unsuitable for certain configurations. In addition, residual stresses can occur because of the granular structure of the material which gives it its strength.

It is important to note that cold extrusion also requires a specific heat treatment to eliminate any cracks, crack formation or rafters.

Therefore, all steel grades do not allow to use the cold forging, especially those with low ductility or sensitivity to cold work. For example, the cold forging is not suitable for low-alloy steel with a carbon content higher than 0.05%.

The hot forging process for manufacturing
The method of hot forging manufacturing is done at extreme temperatures (up to 1150 ° C for steel, from 360 to 520 ° C for aluminum alloys between 700 and 800 ° C for alloys of copper). This temperature is necessary to avoid hardening of the metal during the deformation. Stamping is the hot forging process for manufacturing the most widely used: the material is compressed in a press between a punch and a die.

Hot forged components
  
The advantages of hot forging
The elevated temperature during emitted during the hot forging process allows to reach an extreme degree of deformation of the material and to obtain 3D geometry complexes. The hot forged components are suitable for numerous configurations thanks to their increased ductility. In addition, the technique of hot forging is more flexible than the cold forging, as it allows to manufacture custom parts.

The high quality surface obtained permits to carry a wide range of finishing, such as polishing, coatings or painting, which adapt to each client's specific needs. The hot forging for materials are available worldwide, which positively affects their final price.

The disadvantages of hot forging
hot forged metal properties are obtained by subsequent heat treatment, when the material was quenched to 1000 ° C and then at 500 ° C. This requires additional costs that can be avoided if one uses the cold forging - except in cases of softening, annealing or relaxation.

Another possible downside: hot forged components have a dimensional tolerance less accurate than cold forged components. The cooling process should also be performed in special conditions to avoid the risk of deformation. Furthermore, the granular structure of forged metal can vary and there is always a risk of reaction between the atmosphere and the workpiece.

The cost factor
This complex manufacturing process can be affected by many factors such as suppliers, equipment, management styles, customer demand, etc. Over these constraints are heavier, the risk of disruption of the process and final price fluctuation is large. However, there are four important factors that determine the final price of a forged part:

The amount of material used;
The costs such as electricity, investments, tools, etc;
Heat treatment after forming;
The additional operations such as blasting or quality control tests.
 

The profitability of the blacksmith cold
Cost optimization in the cold forging starts from the choice of raw material. It can be purchased directly, if necessary, annealing and peeling included for the plots can be processed directly. The raw materials used for cold forging are limited and are therefore more expensive. In order to minimize the manufacturing cost, it is best to use cold forming for small parts.

For the most cost-effective, the manufacturing process must be managed by qualified technicians, mastering to perfection each tool or technology involved. For example, large series of cold extruded parts are manufactured on mechanical presses at high speed, but complex parts in small series are rather performed on hydraulic presses.

Effective lubrication system plays a key role in the optimal use of every piece cold forged. All parts must receive a zinc phosphate coating or polymer. Additional lubrication with special forging oil is needed on the presses at several stations. A good lubrication system guarantees the quality of the final part and eliminates additional costs to remedy any malfunctions during the process.

The profitability of the hot forging
Minimizing energy costs during the hot forging process is a constant concern for any manufacturer. These can be optimized through the use of an inductor and a billet of a corresponding diameter, and installing a flexible heating system multistage.

The automation of all involved forging presses is essential for cost efficiency of hot forging manufacturing process, particularly for industries that require high production cycles, such as automotive.

All tools used must be optimized for the following innovative technologies:

Metallurgy: powder metallurgy
Reloading
Heat treatment
Surface treatment: nitriding, carburizing and duplex treatment
 

Main difference between hot forging and cold forging
The cold forging manufacturing method increases the strength of the metal through a hardening at room temperature. On the contrary, the hot forging manufacturing process prevents the hardening of the materials at high temperature, which results in an optimum yield strength, reduced ductility and high hardness.

The manufacturer chooses a process rather than the other for economic reasons and not qualitative. The decision must be taken on the application of the desired component, the type of industry and finally if we want to mass produce and custom parts at low volume.

Setforge provides forging solutions cold at semi-hot and hot , or a combination of different methods for treating various demands of our customers, realized in excellent conditions and with advanced machines for perfect results. We work with our customers to understand their specific needs and find the best possible solution.