The process of forging has been around for centuries with the traditional art of the blacksmiths having evolved into hi-tech and specialised manufacturing practices and forging methods. CAD engineering processes along with high capacity production equipment and tools are now able to meet the changing demands of modern industry.
Forging creates parts, known as ‘forgings’, which are much stronger than those produced by other metalworking processes. Through forging, the sectional thickness and overall weight of a part can be reduced without compromising the integrity of the final product. Forgings are commonly found in applications where reliability and safety are of the utmost importance.
Other important benefits of forging are:
- Reduced material costs
- Shorter lead times
- Extended tool life
While forgings are critical components used in a wide variety of equipment, they mostly go unnoticed as they are generally tucked away in the innards of cars, ships, planes, engines and drilling equipment among other things.
Today’s forging methods for industrial forging still incorporates the use of hammers, although it’s a far cry from the pre-industrial blacksmith working diligently with his hammer and anvil as modern hammers and presses are now powered by compressed air. Evolved forging methods also rely on other modern advancements such as electricity coupled with the use of steam as well as mechanically powered hydraulics.
Common Forging Methods
Open die forging uses hammers and presses to deform a piece of metal between multiple dies that do not completely enclose the material. A series of movements of the ‘hammer’ or ‘stamp’ alters the metal until the desired shape is achieved. The repeated working of the material through this deformation process increases the strength of the materials grain structure, which also results in improved fatigue resistance. Products formed through open forging may need secondary machining to meet specification tolerances.
Open die forging is most often used for short-run forgings of parts that are simple in design such as discs, rings, sleeves, cylinders and shafts. Part weights can range from around 2kgs right up to 200 000kgs.
Closed die forging uses dies that move towards one another, either partially or completely covering a workpiece. This metal deformation process relies on pressure to compress a piece of metal to fill an enclosed die impression. Heated raw material sits in the bottom die, while the shape of the forging is incorporated as a negative image. The force and impact that the top die has on the raw material is what forms it into its shape.
The type of material, tightness of tolerances and the need for heat treatment will determine the number of passes that the product requires through the dies. The common types of equipment used for die forging methods are mechanical and hydraulic forging presses.
Impression die forging uses a horizontal machine called an ‘Upsetter’ to form and produce forgings. The raw material is held between a fixed and moving die while a horizontal ram provides the forging pressure.
Steelmor is the leading supplier and manufacturer of stainless steel in South Africa and has a full range of billets in rounds and square carried in carbon, alloy and stainless steel for forging purposes. Light to heavy forgings are manufactured in our closed die, press and hammer forgings plants. Give us a call to discuss which forging methods best meet your requirements.