The ball cage, also known as the constant velocity joint, is a crucial component in the transmission system of passenger cars, responsible for transmitting engine power to the drive wheels. It consists of components such as a bell housing, steel balls, a cage, a dust cover, and lubricating grease, ensuring equal angular velocity at any angle between the two shafts. 

What is Drop Forging?

Drop forging is a kind of forging process different from press forging, upset forging or other forging processes. In drop forging, the billet is deformed into desired shapes with the help of forging dies. Types of drop forging are open-die drop forging and closed-die drop forging. The shape of the die is the main differences between open die drop forging and closed die drop forging like the names. Closed die drop forging does fully encloses the workpiece, while open die forging does not.

Closed Die Drop Forging

Closed die drop forging, or closed die forging, is a forging way that presses heated round metal bar into the shape we need under the pressure of the dies. It will ensure the accuracy of dimensions and little machining allowance, no structure limit, high production efficiency. General steps of closed die drop forging are: mould developing-raw material cutting-heating material-forging-trimming cutting-heat treatment-shot blasting-machining-surface treatment-package. Materials that applied in drop forging process can be stainless steel, alloy steel, carbon steel, copper and other forged materials.

Design of closed die drop forgings and tooling

The tooling or dies in closed die drop forging are usually made of tool steel. Tool steel will feature closed die forging dies with good impact resistance, high wear resistance, maintain strength at high temperatures, and can even withstand cycles of rapid heating and cooling. In order to produce a better, more economical die, we need to follow below:  

1. The dies part along a single, flat plane whenever possible. If not, the parting plane follows the contour of the part.
2. The parting surface is a plane through the center of the forging and not near an upper or lower edge.
3. Adequate draft is provided; usually at least 3° for aluminium and 5° to 7° for steel.
4. Generous fillets and radii are used.
5. Ribs are low and wide.
6. The various sections are balanced to avoid extreme difference in metal flow.
7. Full advantage is taken of fiber flow lines.
8. Dimensional tolerances are not closer than necessary.

Typical characteristics of closed die drop forgings:

• Under the press of up and lower dies, we could forge the steel bar in fast time,so the production capacity is very high.
• With the help of accurate mould after machining, we could achieve higher accuracy dimensions,which will avoid further machining and save lots of cost.
• Comparing with casting, the mechanical propertity of drop forging will be better, defects can be effectively avoided.