This prestigious heat treat project is highly customized and the system has been designed in close collaboration with the customer to ensure everything meets its specific operational needs.
The contract comprises both high-temperature and low-temperature furnaces, as well as an isothermal cooling chamber and blast cooling tunnel, together with all the ancillary equipment and full material handling and conveying system. The furnaces are designed to be in compliance with CQI-9, the comprehensive audit covering the most common heat treat processes employed by the automotive industry.
Arturo Arechavaleta, NUTEC Bickley’s VP, Metal Furnaces, said: “Our client for this multifaceted project is an auto component world leader that supplies nearly every major vehicle manufacturer. It has an established reputation in delivering the highest quality parts and promoting sustainability in the supply chain. I am delighted that NUTEC Bickley was chosen to partner in the design and manufacture of this isothermal annealing line.”
At the heart of the new facility will be a double pusher tray high-temperature furnace (HTF) that will process carbon steel automotive parts. The furnace will incorporate a fully automatic electrical double pusher system with steel trays sliding over rails with idle rolls. Processing two trays across the width helps reduce the length of the line.
This natural gas unit has four automatic temperature zones, each with two high-velocity nozzle-mix burners that provide excellent turbulence and outstanding recirculation within the furnace chamber. The burners are positioned on top of the sidewalls of the unit, mounted to fire horizontally above the load.
The operating temperature is between 850°C and 950°C (1560°F-1740°F). As with all NUTEC Bickley projects, achieving temperature uniformity is a priority, and the broadest aims here are ±5°C for processes below 680°C, and ±10°C at or above 680°C. The combustion program is based on pulsed firing, with all the latest control software for this type of system.
After initial heat treating, the forged carbon steel parts are moved into an isothermal cooling chamber (ICC), also supplied by NUTEC Bickley. The exit door from the high-temperature furnace links directly to the ICC. Cycling time in the ICC varies between five and 10 minutes – with ambient air being supplied from an external cooling air fan – during which time the load temperature is rapidly reduced from 950°C (1740°F) to 660°C (1220°F), bringing it to transformation point. Tray push rate and maximum product throughput fall into sync with the furnace.
The parts are then conveyed to a second, low-temperature furnace (LTF), and again this matches the high-temperature unit in terms of tray push rate and maximum product throughput. This furnace relies on three automatic temperature control zones and has six burners. It operates at between 630°C and 700°C (1170°F-1290°F) and uses a fuel-only control system for enhanced temperature uniformity.
After the secondary isothermal heat treat process is complete, the tray loads pass into a blast cooling tunnel (BCT). Cooling takes place with air at ambient temperature with forced convection downward by means of two axial fans. By the time parts exit the tunnel, they have been cooled to around 400°C (750°F).
In addition to the HTF, ICC, LTF and BCT, NUTEC Bickley is supplying all the external and conveying equipment for this line, including entrance and transfer cars, complete with car movement system; transfer car tracks; exit transfer cars, with tray dumper unit and car movement; integrated air cooling unit; return conveyor, with electrical dolly system to move trays to the transfer car; and loading station, directly on trays at the transfer car, featuring a carbon steel basket with a lift-rotation movement via a pneumatic cylinder system. The parts handling system operates fully automatically and is linked to the whole process via the Master PLC and HMI.
