Manufacturing Process

Forgings

1.Melting and Ingot Making

Steel is melted and refined by 120 ton basic electric arc furnace. Ladle refining process follows in order to lower gas content and impurities. At ingot making, vacuum casting is applied to obtain good internal quality. Hydrogen in ingot should be reduced as low as possible by means of ladle degassing and vacuum casting. Our maximum ingot weight is 600 ton which is the heaviest in the world. We have also 100 ton Electro Slag Re-melting (ESR) equipment to uniform chemical composition in the ingot.

2.Forging

After heating the ingot to optimum high temperature, the ingot is forged by hydraulic presses (one 3,000-ton, one 8,000-ton and two 14,000-ton). Forging process has two major purposes which are to form the required shape and to refine grain size inside of steel ingot. High fatigue strength is given by this process.

3.Heat Treatment

After forging process, generally, preliminary heat treatment is carried out in order to prevent products from hair cracks and to refine the metallurgical structure of material. After rough machining, quality heat treatment is performed to obtain proper mechanical properties and fine structure. We have low frequency induction heating furnace for Steel Mill Rolls such as high hardness cold mill rolls.

4.Machining

After heat treatment, products are machined. We have more than 100 machines in our machining shop. The major facilities include: 300ton deep hole boring machine, 250ton high speed trepanning machine, 250ton vertical lathe, 350ton vertical lathe, 120kw horizontal boring and milling machine, double housing milling machine and so on.

Castings

1.Pattern making

The Pattern Module is made in accordance with the product Shape.
Recently, it is made by a combination of plywood and polystyrene.

2.Molding

Sand mold is roughly a portrayal of the pattern Module.It is molded by using a mixture of Casting Sand and Binder.

3.Steel melting and Pouring

Melted steel taken out from the Electric Arc Furnace is refined and vacuum treated in Ladle Refining Furnace (LRF).
The Steel whose chemical composition meets the requirements is poured into the casting mold.

4.Flask cooling, Sand removal

Casting is cooled down, taken out from the casting mold and casting sand is removed.100% of the casting sand is recycled.

5.Quality Heat treatment

The casting is heated in an Oven for Quality Heat Treatment to obtain the required mechanical properties.

6.Machining

The casting is machined according to the design requirements.

7.Defect removal and Repair

Surface and internal Defects detected by secure inspections are removed.
Excavations due to the defect removal are repaired by welding.

8.Post Weld Heat Treatment

Post Weld Heat Treatment is performed in accordance with the requirement.Usually Stress Relieving is applicable on request.

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