Types of Cooper Alloys in Forging

The most forgeable (hot) copper alloy is one with 38% zinc and a small amount of lead. This alloy is a two-phase alpha-beta brass at room temperature, but the hot-forging temperatures take the alloy into the single-phase beta region where deformation can easily occur. Lubrication requirements are generally minimal because the copper oxide that forms on the surface is a natural lubricant.

Copper and its alloys exhibit good ductility and are generally considered as easy to forge. When hot forging, the preheat temperatures are typically 1350-1700°F. 

Brass and Bronze are among the most well-known families of copper-base alloys. 

Brass is typically a combination of copper and zinc. Hot brass forging provides for superior density and freedom from flaws, along with dimensional accuracy for duplication of parts. The single-phase alpha brasses are alloys of copper with up to 32% zinc. These alloys can also be strengthened by hot forging.  An unusual property of these alpha brasses is that, in some cases, you can have an alloy with additional zinc and it is both stronger and more ductile than a leaner alloy. The alpha-beta brasses are two-phase metals containing 32-40% zinc.

Bronze is predominantly copper combined with tin, aluminum, silicon or beryllium. Bronze is harder than pure iron and is more resistant to corrosion. Bronze is also harder than pure copper, and over time has been used for weapons, armor and tools.

Copper alloy forgings offer a number of advantages, including high strength, closer tolerances and modest overall cost. Brass forgings are commonly used in valves, fittings, refrigeration components and gas and liquid handling products. Industrial and decorative hardware products also employ forgings. Most copper alloy forgings are hot formed in closed dies. Common forging alloys are the high coppers, C10200, C10400 and C11000, which exhibit excellent ductility, or high strength alloys, all of which exhibit the hightemperature ductile α+β phase structure.

Copper Forging

Copper Forging or Brass Forging is the forging process utilizing copper or brass as the forging material.

Copper alloys have good plasticity and strength, good abrasion resistance and thermal conductivity, especially good corrosion resistance in air and sea water. It has been widely used in electric power, instruments, ships and other industrial sectors.

Most copper alloys have good plasticity at room temperature and high temperature, and can be forged smoothly. Even in the presence of tensile stress, they still have enough plasticity. A few tin-phosphorous bronze with high quality fraction of tin (such as qsn7-0.2) and lead brass with high quality fraction of lead (such as hpb59-1 and hpb64-2) have low plasticity and are sensitive to tensile stress. Qsn7-0.2 is a single-phase invariant solution at room temperature when deformation occurs under static tensile stress. Has the very high plasticity, can undertake cold deformation, but plasticity under high temperature is very low, the reason is that have low melting (alpha + delta + CU3P) eutectic at high temperature.

Most copper alloys are not sensitive to deformation speed and can be forged on a press or hammer, but it is advisable to forge on a press. The phenomenon of heat effect is obvious when tin-phosphor-bronze and manganese bronze are forged. If the deformation speed is too fast, it is easy to overheat or even overheat due to the thermal effect.

When the heating temperature is too high, the copper alloy grain grew up rapidly, reduce its plasticity, so the heating temperature of copper alloy are not more than 900 ℃. When the deformation temperature is below 650 ℃, the deformation resistance increases quickly.

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.