What is a Drop Forging Process?
Drop forging is a hot forging process applied to form the metal workpiece into the desired shape with a die. In this process, the forging machine will raise a hammer and drop it onto the workpiece, making the metal into the dies’ cavities. There are two types of drop forging: open-die drop forging and impression-die (or closed-die) drop forging. As the names imply, the difference is in the formation of the die, with the former not fully enclosing the workpiece, while the latter does.
We can choose the right drop forging process for parts with different characteristics, open-die forging, closed-die forging, or both in the actual manufacturing procedures.
A drop forging production procedure
Open die drop forging
With the open die forging process, the workers need to position the pre-heated workpiece onto the bottom die, and the dies are always with flat surfaces. While the hammer dropped, it will make the metal flowed into the dies’ cavities and get the desired shape. And the reason we call it open-die forging is the formation of the mold, which will not completely enclose the workpiece.
Open-die forging can form the workpiece into shapes including discs, hubs, blocks, shafts (including step shafts or with flanges), sleeves, cylinders, flats, hexes, rounds, plate, and some custom shapes. The advantages of open-die forging include improved microstructure, continuous grain flow, better fatigue resistance, finer grain size, greater strength, etc.
Closed-die drop forging(Impression-die forging)
It is absolutely the same thing when we talk about closed-die forging and impression-die forging. In this process, we place the to-be-forged metal in the die, and when the hammer drops down, it will compress the workpiece into the cavities to get the desired shape. And the whole set of molds will enclose the forged metal completely. That’s why we call it closed-die drop forging.
Closed-die forging has a high initial cost due to the creation of dies and required design work to make dies. However, it has lower recurring costs for greater production volume; this is why we often use closed-die forgings in the automotive and tool industries. Another reason forgings are typical in these industrial sectors is that forgings generally have about a 20 percent higher strength-to-weight ratio than cast or machined parts of the same material.
Advantages of drop forging processes
Along with the drop forging production, we can find many benefits with this process, such as high production efficiency, low labor intensity, accurate size, small machining allowance, etc. However, because the die cost is high and die forging equipment is required, it is not suitable for single or small batch production.
General speaking, the main advantages of the drop-forging processes include:
1. The die’s chamber can guide the flow of the metal so that we can get forgings with complex shapes;
2. The forging flow lines distribute according to the forging’s contour, and it improves the mechanical properties and service life of the parts;
3. Simple operation, easy mechanization, and high productivity;
Why choose NBSJ as a partner for your metal products?
Based on more than 20 years of practice, and overall technical support from our rich-experienced engineering team, NBSJ can supply customers with the most optimal solution to choose the right manufacturing process and material, which expects to save a 10% cost for the project. Meanwhile, based on our service team’s quick response, we are always there whenever you need us, saving time for both of us.
Benefits of NBSJ ’s metal forging factory include:
Our production facilities are equipped with testing instruments, including hardness tester, spectrometer, and metallographic microscopes.
NBSJ can manufacture forgings made of most steel alloys. We can meet your requirements from prototyping to mass production.
A technology supporting team that includes both hands-on production engineers coming from the workshop and professional design engineers from modern universities;
In addition to the drop forging production lines, NBSJ also has other metal manufacturing processes, such as sheet metal stamping, metal casting, CNC machining, Welding, and surface treatment. And that’s why we can meet customers’ demands for a one-stop service of manufacturing a whole set of their products.