Induction hardening uses a magnetic field to heat the surface of conductive materials, producing a hard outer layer while retaining the original material’s strength. The process is ideal for drivetrain components, gears, and tooling, and produces reproducible results at a relatively low cost.
Induction hardening is the manufacturing process that produces a surface hardening of a conductive material by placing that material within a large, rapidly fluctuating magnetic field. The magnetic field induces a temporary electric current that heats the material but only at a fairly shallow depth. The material is then immediately cooled in a bath. The sudden heating and cooling causes crystals to form within the outermost layers of the material, but the core material is not altered and retains its original properties. This dual nature is a key feature of induction hardening.
Hardening of steels and other metals has long been accomplished by heating the workpiece in a flame of some origin or in a furnace and then rapidly dropping the workpiece into water or other coolant. A hardened metal does not gouge easily, slides more easily over other surfaces, and resists wear. The piece is also more brittle and could break or shatter more easily if hit or dropped. By heating only the surface, the hardness characteristic is acquired only by the surface. The rest of the piece maintains the strength of the original material.
Heating a metal or other conductive material by conductance or direct heat causes the entire piece to heat up because electrons are excited and become more mobile, flowing rapidly from hotter to cooler areas. In induction hardening, the outer electrons are “induced” to react to fluctuating magnetic fields by producing electric eddy currents. These currents flow in small circles as the electrons respond to the ever-changing direction of the magnetic field. The heat has no means of being conducted deep into the material.
The type, size and uniformity of crystals formed during the hardening stage of induction hardening determine the ultimate quality of the hardened part. The material undergoes a phase change from solid to crystal called a diffusionless transformation. The atoms move essentially simultaneously for a very short distance. In steel, a very hard crystalline structure known as martensite is usually the final desired form of the surface layer. Martensitic crystals are also found in other hardened materials, including ceramics.
Applications that require strong yet smooth and hard surfaces are ideal candidates for induction hardening. Drivetrain components in automobiles, gears in many applications, tooling that requires tight tolerances, molds, and high-speed manufacturing operations that cut parts all benefit from the dual nature of induction hardened parts. The process is relatively inexpensive; the largest operating cost is the energy input itself. Induction furnaces range from tabletop size to capacity capable of handling major rocket components. Reproducible, high-quality results are standard in these operations.
Protect your devices with Threat Protection by NordVPN
