Gas Nitriding Furnaces by Therelek Engineers

The nitriding process is the phenomenon of diffusing nitrogen into steel and subjecting parts of special steel to the action of ammonia at a temperature normally in the range of 500 to 530°C. The duration of treatment is greatly in usually much more than the common level while in carburizing. In this regard, it should be noted that the normal time for nitriding is usually 90-96 hours.


The main purpose of nitriding is to increase the durability of all types of high-speed steel cutting devices by 100 to 200% on average. It is commonly done in high-speed steel taps, drills, and reamers used in machining annealed steel. In case the nitrided case of any device is removed, when the device is reground, the device must then be retreated, which reduces the cost advantage of the process.

On the other hand, Gas nitriding produces a very case brittle for most applications. Gas nitriding of tool steels is limited to applications such as hot work tool steels (H grades) and tooling for aluminium extrusion dies.

A very popular method of increasing tool life is the process of liquid nitriding of the finished high-speed steel tools in cyanide-base salt baths at 510 °C to 565 °C (950 to 1050 °F). This provides a light case, increasing both surface hardness and resistance to adhesion. This method requires a time range of 15 min to 2 hours, which creates cases with depths up to about 0.05 mm (0.002 in.). The sources for liquid nitriding are going scarce because of prevailing environmental issues.

The treatment of the finish-ground tool in an alkali-nitrate bath or steam oxidation produces oxide coatings that prevent adhesion of the tool along the workpiece. This is possible because the oxide coatings have doubled tool durability, particularly in the machining of gummy materials like soft copper and nonfree-cutting low-carbon steels.

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Gas Nitriding Furnace by Therelek

Pit Type High Temperature Furnace

Pit type sealed retort furnaces are of a cylindrical design vertically erected with a positive sealing mechanism on top in order to contain and preserve heat and atmosphere during a process cycle.

Pit Type High Temperature Furnace

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