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.