Is induction hardening better than flame hardening?

Flame or Induction?

Flame hardening and induction hardening result in identical outcomes in many cases.  The objective of both processes is to form a hard case on the surface of the material while retaining a soft core.

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Depending on the geometry, material composition and hardness specification it is important to select the right process in order to minimize risk and achieve the best possible outcome.

With flame hardening the heat is applied to the surface of the part using a high temperature burner.  The hardness and case depth are basically a function of material composition, surface temperature, soak time and quench media.

With induction hardening heat is generated or induced in the surface of the material by an electric field. Hardness and case depth are basically a function of material composition, frequency, soak time and quench media.  Typical frequencies are 450 kHz (high frequency) for case-depths of 0.75mm (0.030') to 2.0mm (0.080'). Heavier case-depths of 2.5mm (0.100') to 4.0mm (0.150') are typically obtained at 10 kHz.

Pins or shafts are the most common components that are flame or induction hardened. Because of their simple, symmetrical geometry they can be rotated between centres and are well suited to both processes.

With small diameter pins the high heat input involved in flame hardening may result in through hardening.  For this reason we use high frequency induction for pins up to about 50mm diameter.

Flame hardening is a very flexible and cost effective process for small batch quantifies and complex shapes.  Induction hardening is more suited to large batch quantities and simple geometries where the setup time and high tooling cost can be amortized over the larger quantities.

When you are looking to strengthen metals, there are several ways to get the job done. Two common and useful methods are flame hardening and induction hardening. But how do you know which process is going to be right for your project?

When choosing between flame hardening and induction hardening in Gastonia, NC, there are several factors to consider. While they are similar in that both involve heating the metal to a certain temperature and then quenching it, there are some key differences you should be aware of. Here are some of the details of each process.

Flame hardening

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With flame hardening in Gastonia, NC, a metal surface is heated with a high-temperature flame before being quenched. Alloy steels, mild steels, cast iron and medium-carbon steels are good candidates for this process. The result is a hardened surface that has increased resistance to corrosion and wear.

The process involves using direct heat from oxy-gas flames to heat metals to their austenitization temperature (where the surface changes, but the core does not). After being heated, the metal is quenched (that is, cooled rapidly) to develop a hardened surface. This process can be applied to the entire surface or to one concentrated area of a component.

Flame hardening results can vary depending on several factors, including the heat of the flame, how long the metal is heated and the speed and level of change involved in the quenching process. The metal's composition can also play a factor in the hardening results.

The benefits of flame hardening are that it is cost effective and requires a relatively short processing time compared to some other methods. It has a high hardness level that will improve wear resistance. On the flip side, a metal may become more brittle in this process and become more susceptible to cracking. Flame hardening is also not as precise as induction hardening.

Induction hardening

As mentioned, there are similarities between flame hardening and induction hardening. Both heat the metal to its austenitization point and then quickly quench it to induce hardening. But the processes differ in significant ways.

Unlike flame hardening, induction hardening in Gastonia, NC does not use an open flame. Instead, it relies on electromagnetic induction. This process heats materials in a coil with alternating magnetic fields while electric currents cover the surface of the component.

Induction hardening can be used for many types of steel and steel alloys to improve hardness and resistance to fatigue. While flame hardening can be used with a case depth of .127mm to 6.35mm, induction hardening can be used with a case depth of up to 8mm.

Experience is key

Whether you need flame hardening or induction hardening in Gastonia, NC, it pays to look for an experienced, professional company that can handle all of your needs with confidence. J.F. Heat Treating Inc. has been your go-to source for all types of heat treating and hardening services in Gastonia, NC since . If you're looking for the best metal hardening services, contact us today.

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