Heat Treatment After Casting

Continuous Homogenising

The continuous homogenizing center provides fully automated process control, resulting in a user-friendly experience and increased output capacity. Cycle time is reduced by 50% compared to batch-type homogenising furnaces due to process optimization, and the energy consumption is significantly reduced.

Continuous homogenising furnaces with automated processes enable every log to be subjected to the same heat treatment conditions, dramatically improving product quality. With the turbo cooling system, cooling speeds of 1250 °C/h are easily achieved. Crack inspection is done using an ultrasonic test station for alloys used in the aerospace and automotive industries.

The process control system allows for industry 4.0 solutions by integrating recipe monitoring, regional temperature control, customised fan settings, cooling speed control as well as the automated operation of every equipment including burners, fans, conveyors, saws, transfer cars, marking robots, and ultrasonic test stations.

We deliver the following components for continuous homogenising:

Log Loading System
Conveyor for Log Transfer
Station for Ultrasonic Inspection
Machine for Sawing
Transfer Cars
Conveyor for Furnace Log Loading
Homogenization Furnace for Aluminum Logs, Gas and Electrically-Heated (Continuous Type)
Aluminum Logs Cooling Cabinet with Fast Cooling Option (Continuous Type)
Exit Conveyor for Cooling Cabinets
Automated Log Strapping Machines,
Marking Device

Batch Type Homogenising

We also produce reversible batch style log homogenizing furnaces with desired temperature homogeneity within ±5 °C tolerance and capacities ranging from 10 to 110 tones/charge. These furnaces can handle logs ranging in diameter from 4 to 16 inches and lengths up to 8200 mm. Sistem Teknik also offers stacking and de-stacking systems, allowing for safe and simple unmanned loading and unloading operations. In batch form homogenization centres, high cooling rates are achieved by reversing airflow and misting water in cooling cabinets (cooling speed 3 to 4.5 °C/min).

The introduction of automated multi-directional charging cars into the system ensures that logs are safely moved from stations to furnaces and cooling cabinets.

Billet Heating Furnaces

We deliver billet heating furnaces furnaces for pre-heating aluminum logs/billets before extrusion. These furnaces are direct gas-heated and have premix jet type nozzle burners that are PLC-controlled. Because of the unique arrangement of the burners, the logs/billets are quickly heated while reducing gas consumption (18 Nm3/ton Al.).

The temperature is measured within a range defined by surface thermocouples that can be moved back and forth. Following the heating process, the desired material surface temperature remains within tolerance. Waste heat recovery generated in the preheating zone improves heating efficiency. Aluminum billets move through a line in the billet heating furnace, where they are heated by flame through holes placed at an angle at regular intervals on the furnace and exit the furnace in a hot form.

One of the most crucial aspects of these furnaces is that the hot air used to heat the billets creates both homogeneous billets by reusing them and helps preheat the billets, thereby reducing energy consumption. These furnaces are outfitted with low thermal mass insulation materials and easily replaceable refractory blocks for insulation. The furnace transfer system, which includes a roller conveyor, is designed to work in tandem with the hot billet cutting machines. The front heaters and the last zone burners located at the furnace outlet can heat the first 200 mm above the set values (tapper heating).

Stacking & Sawing

Sistem Teknik provides hot saws and hot shears for cutting aluminum logs prior to extrusion. Hot saws with a chip collecting system are recommended for diameters greater than 9”, whereas shears are best for diameters between 4′′ and 9′′. Billets are cut with zero waste using a double cutting system in hot shears. Hot shears communicate with the furnace loading table to cut heated billets to the desired length with a 3 mm tolerance.

Sistem Teknik also manufactures loading conveyors that are installed at the exit of hot shears and saws to directly transfer cut billets to the extrusion press.

Die Heating Ovens

We deliver billet heating furnaces furnaces for pre-heating aluminum logs/billets before extrusion. These furnaces are direct gas-heated and have premix jet type nozzle burners that are PLC-controlled. Because of the unique arrangement of the burners, the logs/billets are quickly heated while reducing gas consumption (18 Nm3/ton Al.).

Continuous T6 Heat Treatment Lines

While we have commissioned more than 60 drop bottom furnaces, mostly in the EU region, in the past twenty years, continuous T6 lines constitute an important part of Sistem Teknik’s R&D agenda. Turning solution heat treatment and ageing into one fully automatic process, continuous T6 lines present great opportunities for technological improvements that increase energy efficiency and product quality. The Sistem Teknik R&D center has implemented several new technologies for continuous T6 heat treatment lines such as an energy-efficient burner mechanism, an automatic temperature control mechanism, and a smart circular airflow system.

Continuous T6 processes can be designed without any additional heating systems for the ageing unit except for a burner that only operates when the desired temperatures are not achieved. The exhaust gas that the heat treatment unit burners produce vary from 300 to 350°C. Instead of releasing it to the atmosphere, the collector transfers this gas to the ageing unit to maintain the oven temperature at 160°C.

This regenerative heating mechanism is controlled by a valve mechanism that operates automatically according to temperature values recorded by the PLC system. The automatic heat transfer control reduces energy use by more than 25% compared to conventional production methods.

While these improvements provide optimal energy use, the innovative circular airflow system in the heat treatment unit grants temperature homogeneity and therefore unfaltering quality results. Microstructural strength is significantly enhanced for individual piece that goes through the annealing process.

Heat treatment includes a solvus curve, but the process also includes solution annealing, quenching, and aging. The average solution period varies depending on the material cross-section:

Heating time: 1.5 hours from 20°C to 540°C
7 seconds of quenching (as the door starts to open)

Maintaining a temperature of 540 °C for 4-5 hours (the maximum furnace temperature is 650 °C)

The furnace elevator and door are designed to minimize the time lost between solution annealing and quenching. As fans continuously circulate the air inside the oven, the temperature homogeneity tolerance is +5 °C. Recuperative burners or hairpin resistors provide heating. The temperature homogeneity tolerance of the tank’s water is also +5 °C.

In the event of a drop in the water level, the tank’s water level can be controlled and an automatic water supply system triggered. The temperatures of the air and water in the furnace and water tank are continuously controlled and recorded in the SCADA system.

Drop-Bottom Solution Heat Treatment Furnaces

For the solution heat treatment of aluminum alloys, drop-bottom heat treatment furnaces are used. Drop-bottom furnaces can be built in a variety of sizes to meet customer requirements. Because solution heat treatment and quenching are combined into a single controllable operation, these furnaces are typically used when very short water quenching times are required.

A drop-bottom furnace sits on a platform, with the quenching tank beneath it. For the quenching process, the furnace platform moves horizontally. The loaded basket is guided into the quenching tank by wire cables. The lifting system can be operated fully or semi-automatically. Recuperative burners or hairpin resistors provide heating.