Metal Case Hardening

Zion is a leading provider of Induction Hardening heating services, including induction hardening, with plants in Michigan, North Carolina and Ohio. Induction hardening is a metal heat treatment process that offers a controllable and localized method of heat without contact to the metal parts or components being heated. The heat is generated by inducing an electric current to flow into a specific area of a part. This provides an economical, targeted and rapid heat treating of conductive materials.

Why use induction hardening?

Induction hardening is favored for parts that are subject to heavy loading. Typical applications include axles, saw blades, shafts, stampings, spindles, gears and most symmetrical parts. Induction hardening is widely used for surface hardening steel, but can be used with other materials as well.

•             Carbon steels

•             Alloy steels

•             Stainless steels

•             Powder metal

•             Cast iron

•             Copper

•             Aluminum

Why choose Zion Industries for induction hardening?

We specialize in induction heat treating for unique part configurations. We can accommodate extreme part diameters and lengths for rolls/shafts and gears. Our power supplies range in size from 5 kW to 300 kW and in frequency from 1 kHz to 450 kHz. Zion has developed an excellent reputation as a commercial heat treating company, producing high quality, on-time work at very competitive pricing.

Although we specialize in high volume production runs, we also have the capabilities to develop prototypes and complete process development work for parts. Zion Industries strictly adheres to ISO/TS16949:2009 standards. We pride ourselves in being one of the largest, most innovative, privately-owned induction heat treating companies in Ohio, Michigan, and North Carolina. For more than four decades, we continue to build an unparalleled reputation for providing innovative process solutions and utilizing state-of-the-art technology and equipment.

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Tempering

Tempering is a low temperature (below A1) heat treatment process normally performed after neutral hardening, double hardening, atmospheric carburizing, carbonitriding or induction hardening in order to reach a desired hardness/toughness ratio.

Benefits

The maximum hardness of a steel grade, which is obtained by Induction Hardening in Faridabad , gives the material a low toughness. Tempering reduces the hardness in the material and increases the toughness. Through tempering you can adapt materials properties (hardness/toughness ratio) to a specified application.

Application & materials

Tempering can be divided into three main groups:

• Low temperature (160-300°C): used for case hardening components and cold working tool steels. Typically, hardness requirement is around 60 HRC.
• Tempering of spring steels (300-500°C): used for spring steels or similar applications. Typically, hardness requirement is around 45 HRC.
• High temperature (500°C or higher): used for quenched and tempered steels, hot working tool steels and high speed steel. The hardness will vary from 300HB to 65HRC dependent on the material.

Process details

The tempering temperature may vary, depending on the requirements and the steel grade, from 160°C to 500°C or higher. Tempering is normally performed in furnaces which can be equipped with a protective gas option. Protective gas will prevent the surface from oxidation during the process and is mainly used for higher temperatures. For some types of steels the holding time at the tempering temperature is of great importance; an extended holding time will correspond to a higher temperature. Depending on the steel grade a phenomenon known as temper brittleness can occur in certain temperature intervals. Tempering inside this temperature interval should normally be avoided. These areas are shown in the steel suppliers steel catalogues, as well as the most suitable temperature depending on hardness requirements.

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What's the difference between single shot hardening and traverse hardening?

There are two methods of heating when using induction: eddy current heating and hysteretic heating. When it comes to hardening, however, the two main types are known as single shot hardening and traverse Induction Hardening in Faridabad. Single shot hardening systems employ the use of rotated components in the induction coil, and the entire area is heated at the same time for a pre-determined amount of time using either a drop quench system or a flood quench system. Single shot hardening is typically used in applications in which no other method will reach the intended result, for example, hardening the flat face of hammers and producing small gears.

Traverse hardening, on the other hand, uses an induction coil for the workpiece to pass through progressively. A following quench spray or ring is used, This process is often used in the manufacturing of shaft type components, including axle shafts, steering components, drive shafts, excavator bucket pins, and power tool shafts. The workpiece is passed through a ring type inductor, which usually features a single turn.

Traverse hardening applications are also used in the manufacturing of certain edge components, including paper knives, lawnmower bottom blades, hacksaw blades, and leather knives.

Ultimately, understanding the processes and details of various induction hardening methods is the key to determining which heat treatment type is best suited for your application needs. For more information about induction heating accessories and other induction equipment for sale, contact Inductwell pvt Ltd

Advantages, Disadvantages of Induction Heat Treatment

The process works on the simple principle that when an electrical current is passed through a conductor, an electro-magnetic field is created around the conductor. The conductor is generally (not in all cases) a coiled copper conductor through which a high-frequency magnetic field is induced to flow through the coil. This sets up a magnetic field around the coil and within the coil. If a steel bar is inserted into the coil, the magnetic flux that is generated will create eddy currents within the surface of the steel bar, which creates heat within the immediate surface of the inserted bar within the conductance coil.

The depth of the heated and hardened surface will be dependent on the carbon content of the steel bar, induction frequency, induction power, residence time within the coil and quench medium.

The steels that can be used for an induction heat-treatment procedure will generally contain approximately 0.3-0.5% carbon. Care needs to be taken with the higher carbon grades for the potential risk of cracking. Chromium can be added to the steel (generally 0.25-0.35%) to interact with the carbon content of the steel and produce surface chromium carbides of Induction Hardening in Faridabad.

It is at this point that the decision should be made if the system will quench with water or a poly-alkaline glycol mixture to reduce the risk of cracking. The Induction Hardening Job Work coil can be designed to accommodate any geometric shape that will allow access to the contour to be heat treated and quenched accordingly.

The following will show some of the advantages and disadvantages of induction heat treatment.

Advantages

•  Localized areas can be heat treated

•  Very short surface heat-up times

• Steel can be pre-heat treated to obtain prior core hardness values

•  Very minimal surface decarburization

•  Very minimal surface oxidation

• Slight deformation (bending); this can occur due to internal residual machining stresses

•  Straightening can be carried out on a deformed bar/shaft; however, care must be exercised

•  Increased fatigue strength

•  Can be incorporated into cell manufacture

•  Low operating costs

Disadvantages

•    High capital investment (however, the investment will be dependent on the degree of automation built into the equipment)

•     Only certain steels can be induction hardened

•     The method is restricted to components having a shape that is suitable for Induction Hardening.

Induction Hardening – Process, History and Advantages

Induction Hardening is a type of heat treatment in which metal parts are heated by electromagnetic induction and then quenched. It is also a type of case hardening and can be used for many steel and steel alloys to improve surface layer properties such as fatigue resistance and hardness.

Induction Hardening Process

Induction Hardening can be split into two steps. The first one is induction heating, in which electrically conducting metals are heated with an electromagnet. The quenching phase follows directly after to alter the surface structure of the material.

Induction Heating

Materials such as steel are typically placed inside a water cooled copper coil where they are subject to an alternating magnetic field. They undergo electromagnetic induction by means of an electromagnet and an electronic oscillator. This oscillator sends alternating currents through the electromagnet, causing alternating magnetic fields that penetrate the material. The results are eddy currents (loops of electrical current) which heat the object within the coil. Induction hardening is a form of surface hardening in which the depth can be up to 8mm. The deeper the currents penetrate, the higher the frequency of the alternating magnetic fields have to be Case Hardening in Faridabad.

Steels that have a ferromagnetic structure (which is inherited from the iron) can also be heated by magnetic hysteresis losses. Magnetic hysteresis losses produce heat by re-aligning magnetic domains, although it depends on the frequency of the currents, the penetration depth and the properties of the material (size, density, alloys) how much heat can be generated.

Quenching

Directly after the induction heating process, the object has to be quenched, meaning that it has the be cooled down extremely quickly. To do that, the workpiece is typically placed in a tank of oil or water, although sometimes cold air is used. Quenching ensures that only the surface is hardened and that heat doesn’t spread into the core of the material, avoiding phase transformations from arising. Furthermore, the rapid cooling down creates a martensitic or ferritic-martensitic structure on the surface layer. These structure display higher tensile strength and low initial yielding stress than a purely ferritic structure.

History

Induction heating was first developed and introduced in its earliest form in 1831 by Michael Faraday. He could prove that an electromotive force could be created by winding two copper coils around a magnetic core while turning one of the windings on and off which affected the other one. These currents were created by alternating magnetic fields around the magnetic core. Because neither of the coils touch, the electromotive force is induced into the second coil, the process was called induction heating.

Properties that improve due to induction hardening

Deeper Case Depth: Induction hardening can penetrate the surface of up to 0.31 inches (8 mm). This depends on the process of induction hardening and the material’s properties.

Finer Grain Size: As mentioned above, induction hardening changes the grain size on the surface of materials. A finer grain size increases hardness because the surface is harder to penetrate.

Higher wear and fatigue resistance: Induction hardening improves wear resistance because the structure of the surface layer is altered. Ferritic steels obtain a martensitic structure which provides improved wear resistance.

Induction hardening in Faridabad is a good alternative to boronizing, which is a type of surface hardening BorTec specializes in. Induction hardening is recommended when only hardness should be improved. If you’re looking for a treatment that can also improve adhesion, resistance against abrasive wear, good stability at high temperatures and resistance against acids, the certified BoroCoat treatment is the better choice. However, it depends on the area of application and other factors which hardening technique is more suitable for your needs.

Total vs. Effective Case Depth

One of the benefits of induction hardening is the ability to selectively apply a surface hardness or case hardness to steel materials. The case hardness will allow the piece to have superior wear and strength characteristics at the surface, but allow the interior of the piece to remain flexible in Induction Hardening in Faridabad.

Case hardness is defined as the outer surface that has been made harder than the interior, or core. The term case depth refers to the depth of the case, or hardened layer of a piece of material. Case depth is typically measured as “total” or “effective”. The two terms are sometimes misunderstood, but are different and it is important to understand those differences.

The term total Case Hardening in Faridabad refers to the depth of hardness where the hardened layer reaches the same hardness and properties as the base or core material. Total case depth is typically measured by sectioning the work piece and polishing and etching with an acid solution to reveal the depth of the hardened layer. The measurements can then be taken visually and measured using a calibrated eyepiece or scale to qualify the total depth.

The term effective case depth refers to the depth where a hardness measurement drops below a specified point. The hardness will then continue to decline until the “total” case depth is reached. The hardness at the effective depth is specified based on the characteristics required and the hardenabiltiy of the material. For example, high carbon steel that may have a minimum surface hardness of 60 HRc may call for an effective case depth of 0.120” at 50 HRc. The method of determining effective case depth involves sectioning the piece and polishing the surface. Measurements of the hardness are then taken at regular depth intervals until the hardness drops to the specified range. This distance from the surface is then measured to determine the effective depth in Induction Hardening.

Heat and surface treatment

Rolling bearing rings and rolling elements must:

•  be hard enough to cope with fatigue and plastic deformations

•  be tough enough to cope with applied loads

•  be sufficiently stable to experience only limited changes of dimensions over time

The required properties are achieved by heat and surface treatments of Induction Hardening in Faridabad.

Hardening

There are three typical hardening methods that may be applied to bearing components:

•  Through-hardening

          This is the standard method for most bearings and provides good fatigue and wear resistance,               as hardening is applied over the full cross section.

•  Induction-hardening

         Surface induction-hardening is used to selectively harden a component’s raceway to limit                    rolling contact fatigue, leaving the remainder of the component unaffected to maintain structural 

•  Case-hardening

Case Hardening in Faridabad provides hardness to the surface. It is used, for example, where bearing rings are subjected to high shock loads causing structural deformations.

Dimensional stability

Heat treatment is used to limit dimensional changes due to metallurgical effects at extreme temperatures. There is a standardized classification system for dimensional stability. The various SKF bearing types are stabilized to different classes as standard.

Surface treatment and coatings

Coating is a well-established method for providing bearings with additional functional benefits to accommodate specific application conditions. Widely used coatings are zinc chromate and black oxide.

Two other methods developed by SKF have proven successful in many applications:

• INSOCOAT bearings are standard bearings that have the external surfaces of their inner or outer ring coated with an aluminium oxide layer. This coating increases resistance to electric current through the bearing.

• NoWear enhances wear-resistance of the raceway or rolling element surfaces. It can help the bearing withstand long periods of operation under poor lubrication conditions and to reduce the risk for low load damages Induction Hardening.