Stainless Steel Forging Techniques
There are numerous types of forging available to form stainless steel components; we shall examine two of the more popular ones below.
1. Press Forging
This method employs a press, usually hydraulically operated, which squeezes the hot metal into a die.
This method is used mostly for large castings of around 250lb weight and length of10feet. The force from the press is transferred uniformly to the component eliminating stresses, a requirement of the larger, heavier forged components.
To ensure extraction from the die generous radii are left at corners and any undercuts avoided, a lubricant is also used in this process.
2. Open Die Forging
This method evolved from the village local smithy, now all but sadly gone, although we used to have a farrier who would knock up a special component, such as old gate hinges or various odd shaped brackets for old motor bikes I was working on at the time.
Anyway, the principle of open die forging consists of the hot metal being located on a stationary horizontal die, the upper die being connected to a drop hammer, usually operated by air. The hammer speed used to be controlled by an operator; but nowadays modern machines are automatic, with the hammer in contact with the component for milliseconds.
However, the operator still manipulates the component in the dies, and a further process known a blocker forging may be required. This is just a refinement of the drop hammer, using another set of dies, and gives a better, more accurate finished product.
This method ensures even distribution of the metal grains, giving a stress-free, strong component that is easily machined and coated, being suitable for many sizes and weights of component.