HEAT TREATMENT: WHAT IT IS AND HOW IT WORKS

HEAT TREATMENT: WHAT IT IS AND HOW IT WORKS

 by General Kinematics, December 1, 2020

What is Heat Treatment?

Although most people don’t know what heat treatment is, it’s actually an essential part of the manufacturing process. That’s because heat treating allows a metal piece to be improved in order for the material to better withstand wear and tear. Heat treatment involves heating a metal or alloy to a specific temperature and then cooling it to harden the material. 

Heat treatment can be used at different stages in the manufacturing process to change certain properties of that metal or alloy. For example, you might use heat treatment to make it stronger, harder, more durable, or more ductile, depending on what the material needs in order to perform properly. 

Some notable industries in which heat treatment plays an important role include aircraft, automobiles, hardware–such as saws and axes, computers, spacecraft, military, and the oil and gas industry.

How Does Heat Treatment Work?

In order to achieve the desired effect, the metal or alloy is heated up to a specified temperature, sometimes as hot as 2400°F, held at that temperature for a certain amount of time, and then cooled. While it’s hot, the metal’s physical structure, also called the microstructure, changes, ultimately resulting in its physical properties being changed. The length of time the metal is heated for is called the ‘soak time.’ The length of soak time plays an important role in the characteristics of a metal, as metal soaked for a long amount of time will see different microstructure changes than metal soaked for a shorter period of time. 

The cooling process after the soak time also plays a part in the result of the metal. Metal may be cooled quickly, which is called quenching, or slowly in the furnace to make sure it achieves the desired result. The combination of the soak temperature, soak time, cooling temperature, and cooling duration all play a role in creating the desired properties in a metal or alloy.

When the metal is heat-treated during the manufacturing process also determines what properties are changed, and some metals may even be treated multiple times.

Knowing what temperatures to heat and cool metals at, as well as how long each step of the process should take for a specific metal or alloy is extremely complicated. Because of that, material scientists known as metallurgists, study the effects of heat on metal and alloys and provide precise information on how to perform these processes correctly. Manufacturers rely on this information to ensure their metal pieces will have the correct properties at the end of the process.

Some common forms of heat treatments include:

• Hardening: When a metal is hardened, it’s heated to a point where the elements in the material transform into a solution. Defects in the structure are then transformed by creating a reliable solution and strengthening the metal. This increases the hardness of the metal or alloy, making it less malleable.   
• Annealing: This process is used on metals like copper, aluminum, silver, steel, and brass. These materials are heated to a certain temperature, are held at that temperature until transformation occurs, and then are slowly air-dried.  This process softens the metal, making it more workable and less likely to fracture or crack. 
• Tempering: Some materials like iron-based alloys are very hard, making them brittle. Tempering can reduce brittleness and strengthen the metal. In the tempering process, the metal is heated to a temperature lower than the critical point to reduce brittleness and maintain hardness. 
• Case Hardening: The outside of the material is hardened while the inside remains soft. Since hardening can cause materials to become brittle, case hardening is used for materials that require flexibility while maintaining a durable wear layer. 
• Normalization: Similar to annealing, this process makes the steel more tough and ductile by heating the material to critical temperatures and keeping it at this temperature until transformation occurs. 

Why is Heat Treatment Important?

Without heat treating metal, especially steel, metal parts for everything from airplanes to computers wouldn’t function properly, or might not even exist in the first place. Non-ferrous metal parts in particular would be much weaker. Aluminum and titanium alloys, as well as bronze and brass, are all strengthened through heat treatment. Many of these metals are used in the production of cars, airplanes, and other products that rely on strong metals not only for performance but for safety as well.

Because heat-treated metals are often stronger than non-heat treated metals, treating metal pieces upfront prevents corrosion, which won’t result in the replacement of expensive metal parts later on or as frequently. This causes machines to run more cheaply and efficiently and prevents problems.

Solutions from General Kinematics

General Kinematics provides optimal equipment in order to improve and boost productivity in the heat treatment process and other manufacturing processes. There are various steps when dealing with heat treating metals, General Kinematics provides foundry equipment designed to aid in this process and to increase manufacturing productivity. 

Conveyors 

General Kinematics SPIRA-FLOW™ vibrating spiral elevator is ideal for heat-related treatments that require a long conveying path, but it condenses it into a spiral shape in order to take up less space. The Spiral-Flow is a great fit for manufacturing plants that are tight on space or want to optimize their use of space. 

General Kinematics offers a wide range of additional conveyors for a multitude of heat treatment needs. Whether you are looking to move your materials from point A to point B, heat, cool, or more GK has the equipment you need to improve your processing power.

Feeders

Feeding material into the desired heat treatment process is ideally performed by industrial material feeders. General Kinematics Two-Mass Vibratory Feeders are designed to withstand the harshest and most demanding applications. They are equipped to take on the most challenging material loads in order to keep your process moving smoothly. GK Feeders are engineered to order and are low maintenance, meaning less downtime and more productivity. 

General Kinematics offers a variety of high-performing industrial equipment designed for various industries. See what else General Kinematics has to offer and how our industry-leading equipment can help your organization.