Product Description and Process
house samples of drop forging process China
Production process: metal hot forging process
Machining process: CNC machine, machining center, lathe, mill machine, drill machine, etc.
Surface treatment process: paint coating, electrophoretic coating, electrogalvanizing coating, black oxide coating, powder coating, etc.
Product Material and Uses
Normally produce with low carbon steel, medium carbon steel, low alloy steel, such as 1020 steel, 1035 steel, 1045 steel, 16Mn, Q235, Q345, A105, 20MnMo, 35Crmo, 42CrMo, etc.
The steel forging products are widely used for auto-car parts, truck parts, train parts, vehicle components, construction machinery components, other machinery components, etc.
What is Drop Forging?
Drop forging is a metalworking process that gradually shapes a heated piece of metal, called aningot. It involves forming the ingot with repeated blows from a hammer or die that is raised and then dropped onto the part, flattening it or forcing it into a mold. Depending on the complexity of the part design, the process sometimes requires using several dies in progression. The drop forging process usually produces a close approximation of the finished piece, but additional machining typically is required to bring it within tolerance. Drop forging is widely used throughout the automotive industry in producing various engine parts, gears and axles.
The dies used for drop forging typically are made of a high alloy steel, called tool steel. Forging dies are designed to be impact resistant and wear resistant, and they generally can withstand thousands of rapid heating and cooling cycles. Drop forging dies are usually made in two halves. The upper half, called the hammer, is attached to the block that is raised and dropped onto the ingot. The lower half, called the anvil, usually is a stationary die against which the ingot is forged.
Open-die drop forging is done with dies that do not completely enclose the workpiece. The dies usually are flat, although contoured dies or cutting dies can be used as well. The open design allows room for the ingot to expand as it is hammered to the desired thickness.
Techniques commonly associated with open-die drop forging include cogging and edging. Cogging is the process of progressively flattening a bar or ingot length-wise. This process is used to achieve the desired thickness, after which it can be edged. Edging is usually done with a concave die. This technique concentrates and shapes the material along the sides and ends of the forged part in order to achieve uniform edges and proper width.
Impression-die forging, sometimes referred to as closed-die drop forging, uses mold-shaped dies. When the hammer is dropped onto the workpiece, the hot metal is forced into the die cavities to create the final shape of the part. As the metal is forced to conform to the die, excess material, called flash, is squeezed out. The flash must be removed after the forging is completed.
Another common type of closed-die forging is called flashless forging. This process is also referred to as true closed-die forging, because the workpiece is completely enclosed by the die, preventing flash from forming. Many manufacturers prefer flashless forging because the flash produced by impression-die forging can account for almost half of the original ingot.
Drop forging process
General closed die drop forging process includes dies making, billet cutting, billet heating, drop forging, trimming, heat treatment, shot blasting, machining, surface treatment and inspection.
Below we would like to introduce the drop forging process in detail.
Step 1.Dies design & making
Making dies is the first step for starting drop forging process. We will first design and produce dies according to the die drawing. Such dies normally include forging dies, trimming dies and flat die. Among these dies, flat die is not necessary, as it is just used to use to flatten the products to ensure geometric tolerances.
Step 2.Billet cutting & heating
Normally, we will prepare commonly used material specifications(like 20#,35#,45#,20Cr,40Cr,20CrMnTi,20CrMo, 30CrMo,35CrMo,42CrMo,Q235,Q345,A105,ect) in stock, and cutting the billet to the estimated size. Then using the medium frequency furnace to heat the billets to a certain temperature, after that deliver the heated bars to a metal frame and wait for forging.
Step 3.Drop forging
Before forging, forging upper and lower dies will be attached to the anvil of forging press. Then workers will pick up a billet and place between forging dies so that the billet will be pressed at a high speed for several times to desired shapes.
After forging, we will see the redundant flash around the drop forging blanks. So removing flash is also a necessary step. Workers will first assemble the trimming dies under the punching machine, and then press the forging blanks at a time so that flash will be removed. We call this process "trimming".
Step 5.Heat treatment
Heat treatment will help to reach the required mechanical properties and hardness. Such heat treatment processes are normalization, quenching, annealing, tempering and hardening, solution treatment, etc..
Step 6.Shot blasting
By shot blasting, the drop forgings will look more smooth and clear. You will see a better surface finish. Normally, the surface finish of drop forging products will reach Ra6.3, whose surface is much better than that of lost wax casting.
For some parts, drop forging process is not enough to get the required tolerance, then machining will be workable, we will do machining with different machining facilities, such as milling machine, boring machine, drilling machine, grinding machine, cnc, etc..
Step 8.Surface treatment
In most cases, we will just do water/oil anti-rust on the surface of drop forgings if there is no special requirement. But we could also follow other surface treatment demands, like painting, powder coating, galvanization, electro painting, etc., according to the requirement of our customers.
Step 9.Final inspection
To ensure superior quality, we must do dimension inspection. Sometimes we also need to do inspection for mechanical properties and chemical composition.
Usually, we will pack the forgings with ploy bag, and put in a strong wooden case. Such package could also be customized to meet customer's demand. Located in Zhengzhou, both the seaport and airport are very convenient for us to deliver products to our customers' destination port.