Forging is a manufacturing process with many years of history: according to experts, the first implements made by this process date back to 3,000 BC, and it is believed that the Greeks were familiar with this technique as early as 1,000 BC.
Since then, forging techniques have changed greatly, owing to a series of technological advances. Currently, it is possible to forge in two ways that allow material to be formed in a controlled manner until it attains the desired shape:
- by pressure. In this case, presses, either mechanical or hydraulic, work continuously.
- by impact with hammers that strike either via gravity or via an energy source.
The advantage of forging over other processes such as machining is that there is no milling down needed, so less material is lost. In addition, the structural properties of the material are improved, resulting in materials of great hardness and toughness.
Different forging processes
Different types of forging exist. The most common are the following:
- Open-die forging. This is the oldest method, without the use of complicated machinery. The smith hammers out the desired shape with each stroke in an artisanal manner. This technique is used in manufacturing single pieces or for small batches usually of large pieces.
- Closed-die (or impression-die) forging. The piece is placed between two dies that close to create the desired shape and size via press or hammer action.
- Upset forging, either hot or cold. The tools used are smooth, so that the only force acting on the piece is compression.
- Isothermal forging. The dies are kept at a controlled temperature throughout the forging process.
Most used materials in the forging industry
Forging is a process that accepts a wide variety of materials, but the most common are: carbon steel, alloy steel, stainless steel, duplex and aluminum alloys, titanium, nickel, copper and brass.
Forged steel for industry
Forged steel is an alloy of iron and carbon that is compressed under extreme pressure with specialized machines and hydraulic hammers to obtain a very hard and strong material.
To shape it, we use pressure and strong blows from hydraulic and mechanical presses and hammers to give pieces the required shape and form.
This results in improved mechanical properties for the forgings.
Forged steel is mainly used in various industries: automotive, construction (e.g. bridges and structure framing), aeronautics (aircraft), petrochemicals and agriculture.
Stainless steel for manufacturing
Stainless steel is an alloy of steel and chromium, though it can also contain other metals. It is a material that is highly resistant to corrosion, since both the chromium and the other materials used in the alloy are oxygen tolerant.
It is used in the manufacture of household appliances, automobiles, construction (buildings and street furniture), industry (food, chemicals and petroleum), and jewelry, basically when better mechanical and chemical properties are required than are possible with carbon steels.
Aluminum and its alloys
Aluminum is one of the most widely used materials in forging as it has different applications, the main ones being industry, commerce and specialized sectors.
The great advantage of aluminum is its lightness, as it has a lower density than carbon steels, resulting in lighter-weight products.
The forgeability of aluminum alloys differs from that of traditional carbon steels, but the same production methods are used.
This material is used, among other things, for urban vehicles and others where weight is critical.
Forged titanium for engines and structures
Titanium is a material that is abundant in the earth’s crust, which is why it has been used for so long.
It is often compared to steel because both are hard and resistant to corrosion, but it has other characteristics that set it apart:
- Conducts heat and electricity
- Withstands high temperature
- Non-magnetic
- Malleable, hard and light, with a high strength-to-weight ratio
- Very aesthetically pleasing
Forged titanium is used in engines and aeronautical structures, but it also has other lesser-known applications: prostheses and surgical tools in the medical sector; tennis rackets, cricket or soccer helmets, etc. in sports, and jewelry as it is visually very beautiful. It is also used in the production of radioactive waste containers due to its resistance to corrosion.
