With 4 well-equipped manufacturing units spread across 8 acres, Kalliyath is the only brand in Kerala that produces 6mm original TMT Steel bars and also the only brand in India to produce Fe 500 graded 6mm bars with ISI certification. At Kalliyath, each TMT Steel bar is made from the 100 Meter Automated High-Speed Rolling Mill in adherence with the BIS quality standards and norms to ensure quality consistency.

From mega infrastructure to landmark construction to individual homes, there is an exponential demand for reinforced bars in every segment of the industry. This paved way for many small scale and low-quality manufacturers to enter into the industry. And the infrastructure market is now replete with low-quality TMT Steel bars which are made without following the necessary BIS instructions. To solve this mounting problem, Kalliyath helps people understand what a real TMT Steel bar is.

Original TMT Bar

TMT Bar also known as Steel Reinforcement Bar or Thermo Mechanically Treated Bar is the inner strength of construction industry. It protects the structure’s materials from weather and extreme temperatures. Therefore from the selection of raw materials to the manufacturing process of TMT Steel bars, special care and attention should be given.

Selecting the Raw Materials

Selection of raw materials is the most important factor that determines the quality of a TMT bar. At Kalliyath, Steel is produced using high-quality raw materials supplied by world-class suppliers of billets from virgin iron billets like Vizag, SAIL etc. Raw materials for making TMT are also manufactured by Kalliyath to maintain consistency in quality. The raw materials Kalliyath uses have three main advantages.

  • The unique combination of all chemicals and substances
  • No decrease in strength even after reduction
  • Selected raw materials certified by BIS for the making of Fe 500 TMT bars

temperature of billet

The process utilize residual heat from the rolling process to attain the desired mechanical properties. Billets, which are heated in the re-heating furnace, are rolled through a series of rolling stands and progressively reduced to the final desired size and shape. The most important factor in this stage is that the temperature of billet should be 1,2000C.

automated high speed rolling mill

With the help of computerized process, qualified engineers of Kalliyath passes the 1,2000C billets to the special automated high-speed rolling mill. The process is controlled by monitoring devices, in an all mechanized technical operational environment. This enables the production of rebars with perfect shape, uniform thickness and equal standard length. The rolling mill operating in tandem with the continuous casting machine cools the billet temperature to help reduce the material and within 40 seconds, these billets are made into TMT bars ensuring excellent dimensional tolerance and surface finish.

Most of the rolling mills in Kerala have the manual process which takes too much time and lacks the temperature required for processing. This leads to the loss of quality of the TMT bar.

necessary stages

For reduction, billets are passed through the vast automated high-speed rolling mill units of Kalliyath. Normally, TMT bars needed for gauge are passed only 15 to 19 times. But at Kalliyath, bars are passed 21 to 25 times to ensure uniform size, shape and strength to decrease the production time. Mills that work with manual technology reduce the number of passes which results in the loss of quality, strength and unique shape of the TMT bars.

quenching process

The hot rolled rebar emerging from the finishing stand mill will be of 4000C. These bars are then rapidly cooled by Quenching Process. The Quenching Process by a special water spray system converts the surface layer of the bar to a hardened ‘Martensitic’ structure while the core remains ‘Austenitic’. The process pressurizes and deforms the crystal structure of intermediate layers, and simultaneously begins to tamper the quenched layers using the heat from the bar’s core.

automated cooling bed

TMT bars that comes out after the Quenching Process will be of 2500C. These bars are cut into desired sizes and then passed through Automated High-Speed Cooling Bed. This stage involves normal cooling to room temperature where the ‘Austenitic’ core is transformed to a ductile ferrite + pearlite structure. This finished bar has a microstructure comprising of a tough outer layer of tempered ‘Martensite’ and a ductile core of ‘ferrite + pearlite’. This composite structure gives excellent yield strength to the bar along with superior ductility and weldability. The mechanism of automated cooling bed assures that the bars are uniformly positioned over the toothed racks. The advanced technology helps prevent the damages caused by the collision of TMT bars and thereby gives a unique uniform strength and shape. But in Manually operated rolling mills, labours do this with a hook. The increased strength and toughness of TMT bars create problem during subsequent manual bending operation. It will affect the shape and strength of the TMT bars.

stringent quality control

TMT bars made through this process are then sent to specially arranged labs to test the quality and strength by suing the right chemical composition of F500 grade set by BIS. Also, the sectional weight and strength of each unit of TMT bar is tested every 30 minutes to give customers the best ever.

Kalliyath TMT bars have precise, uniform and parallel rib pattern engraved through computer controlled notch making machines, which results in excellent bond strength with concrete. The right combination of chemicals in Kalliyath TMT bars ensure easier and faster welding without pre-heating. This means stronger and safer weld joints and reduction in wastage during welding at the site. Kalliyath TMT bars are proven to have a higher resistance to cyclic loading conditions and are recommended in earthquake prone areas due to their superior seismic resistant properties. Due to the highly controlled process that ensures a microstructure with a soft core, Kalliyath TMT bars have excellent bendability, making work easier and faster at construction sites.

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