Thermal Process Technology /
Tempering Plants for Aluminium and Steel

Drop-Bottom Furnaces Electrically Heated or Gas-Fired

Fully automatic drop-bottom furnace with movable water bath, including holding position for charging and unloading crane

Drop-bottom furnace with stationary quench tank

Drop-bottom furnaces are used for solution annealing and subsequent rapid quenching of aluminum alloys. In particular, with thin-walled aluminum components quench delay times of just 5 seconds from when the door begins to open until complete immersion in the quench tank are required. Generally, these requirements can be met only with this furnace design. The drop-bottom furnace stands on a base so that a quench tank can be positioned directly below the furnace. For the quenching process, the furnace bottom moves horizontally to the side. The loaded basket drops out of the furnace into the quench tank guided by wire cables. The lifting system can be controlled automatically or semi-automatically. Because of the broad working temperature range, drop-bottom furnace plants allow complete T6 heat treatments, consisting of solution annealing, quenching, and artificial aging in just one furnace.

Drop-bottom design alternatives

  • Drop-bottom furnace with stationary quench tank as a cost-effective, space saving variant
  • Drop-bottom furnace with movable quench tank, including holding position for charging and optional unloading crane
  • Customized designs with several furnaces, several tanks and several holding positions for fully automatic processing of several charges

System details

  • Working temperature range between 80 °C and 600 °C
  • Working temperature can be extended to 650 °C
  • Heating generally electric; direct or indirect gas heating is also possible
  • Air flow, depending on space conditions and charge geometry, horizontal or vertical
  • Compliance with relevant aircraft and automobile standards, such as AMS 2750 E, AMS 2770/2771, or CQI-9 as an option

Fully automatic drop-bottom furnace plant, consisting of two drop-bottom furnaces, movable water bath and several loading and unloading positions

Control, visualization and documentation with Nabertherm Control Center NCC

Quench Tanks

Water or polymer quench tanks have a single stainless steel wall and have an integrated circulation system of the quenching medium for effective removal of energy from the charge. Temperature and level are monitored. All tanks have connections for water feed and drainage and a heat exchanger. On request, the quench tank can be equipped with a controlled heating to pre­heat the quenching medium and/or a heat exchanger for cooling. If the quenching medium is to be kept continuously at a high temperature, a tank insulation with or without cover is recommended.

Based on Siemens PLC technology the system is operated conveniently with PC-based Nabertherm Control Center software. Components can also be moved manually via a Mobile Panel.

Customized drop-bottom designs are tailored and manufactured to customer needs.

Size examplesTmaxWork space dimensions in mmVolumeOuter dimensions in mmHeating powerElectrical
Model°Cwdhin lHin kW1connection*
FS 2000/60HAS6008001200120020005377**723-phase
FS 2200/60HAS60011001100110022005550**843-phase
FS 5350/60AS60014001400120053507524**1963-phase
FS 5670/60AS60015001500135056706452***1963-phase
1Depending on furnace design connected load might be higher *Please see page 81 for more information about supply voltage
**With quench tank on cart
***With quench tank in a pit

Quench and Temper Plants for Steel

Fully automated tempering plant with two chamber furnaces, quench bath, conveyor system, and parking spots for four charge baskets Annealing furnace with manipulator

Tempering plant with top hat furnace H 4263/12S and water bath

The charge is placed in the hot furnace by a manipulator and is also removed and transferred to the quenching medium while it is hot.

To temper steel, after annealing the furnace is opened at working temperatures of more than 1000 °C. The lift door opens and the manipulator places the charge into the quenching medium. After quenching the charge is placed into the forced convection chamber furnace for tempering. Good temperature uniformity is important.

Oil or water is used as a quenching medium. Depending on the steel grade and the required cooling rate, the charge can also be force-cooled or quenched in an air quenching chamber.

Alternative plant designs are tailored to process requirements. For lighter charge weights a manual tempering plant can be used, consisting of an annealing furnace, quench tank and manual manipulator. Semi-automatic or fully automatic plants are used for heavy loads and high throughput rates. The charge is placed into the hot furnace and subsequently into the quench tank by a manipulator.

The customer specifies the needed quenching delay time for the individual process counting from opening the furnace door until the charge is completely immersed in the quenching medium. Fast delay times are only possible with a powered manipulator. If the quenching delay time is not so critical, for example for heavy and thick-walled parts, bogie hearth furnaces can also be used. The bogie is driven out of the furnace electrically and the components can be transferred and quenched by a crane.

Top hat furnaces are suitable for long components or for processes with no need for short quenching delay times. The top hat is opened while the furnace is hot and the charge is then transferred and quenched by the customer’s crane with a C-hook.

Annealing Furnace Design Alternatives

  • Chamber furnace with radiation heating and a lift door for charging with a manipulator
  • Bogie hearth furnace with powered bogie for charging with a crane for low quenching delay time requirements
  • Top hat furnace for long components, such as rod material for charging with a crane and C-hook

Quenching Design Alternatives

  • Quench tanks with water, oil or polymer as a quenching medium
  • Cooling station with powerful fan cooling for air quenching.

Charge Transfer Alternatives

  • Manual manipulator for manual tempering plants
  • Electric manipulator for manual tempering plants
  • Rail-mounted 2-axle manipulator, semi-automatic for charging, unloading and quenching the charge in a liquid medium
  • Rail-mounted 2-axle manipulator, semi-automatic or fully automatic for charging, unloading, quenching, subseguent tempering in forced convection furnace or transferring to a holding position