Annealing furnace - GLO

The GLO annealing furnace features a vacuum tight retort with highly symmetric positioning of the heating elements. The heating elements are CrFeAl, also known as APM, and are embedded in the ceramic fibre insulation.

The GLO is often equipped with a vacuum pumping system to reduce the Oxygen levels prior to heat treatment. To ensure the lowest possible contamination levels, several cycles of vacuum and Nitrogen purging occur to create a pure atmosphere in the retort. Vacuum assisted cycling is far superior compared to simply flowing Nitrogen through the retort as the process creates a pure atmosphere faster and requires less Nitrogen. After Oxygen levels have been reduced, heat treatment begins under an inert atmosphere with a slight overpressure.

The highest possible temperature of the GLO annealing furnace is 1100°C for heat treatment with an atmosphere. The front door of the cylindrical retort can be heated if required. At the water cooled front door, the gas is purged inside the GLO. It is preheated by the radiation shields, which are inserted at the front. The GLO is provided with a rear port for the expulsion of any gaseous by-products generated during the process.

The GLO can be operated manually or with the use of an automated system. The furnace is available in sizes of 5, 10 (mobile version), 40, 75, 120, 260, 400, 550, 600, 850, 950 and 1300 litres. The retort is manufactured with temperature resistant steel alloy (1.4841). Other materials are available on request.

The annealing furnace may be operated with reactive gases such as Hydrogen, which requires appropriate safety technology. The Hydrogen safety system includes an automatic operating system with a Nitrogen flooding tank to detect and purge the system should any malfunctions be detected. All devices are SIL2 certified.

The furnaces have a compact, space saving design. The debinding package allows for debinding or pyrolysis processes to be carried out. Virtually no condensation occurs as the unit is equipped with an afterburner and heated gas outlet for strong outgassing applications.

The GLO can be equipped with a fast cooling system. The retort can be air cooled from the outside or purged with cold, inert gas.

The GLO furnace is also available in two alternative versions:

1. The vertical VGLO is loaded vertically and therefore provides a compact, space saving design.
2. The mobile GLO is a transportable, space-saving version for flexible use in different applications.

Standard features

• Manual control
• Gas tight retort made of 1.4841 (equals grade 314) stainless steel
• Water cooled door with gas tight rubber sealing (water cooling must be provided at customer site)
• Radiation shields
• Gas control with manual control for a single inert gas, air or formation gas
• Precisely controlled atmosphere with highest possible purity
• Over-temperature protection (recommended to protect valuable contents & for unattended operation)

Options (specify these at time of order)

• Vacuum System: pre-vacuum pump, roots pump, or turbomolecular pump
• A range of sophisticated digital controllers, multisegment programmers and data loggers with digital communication options is available - more information about controllers
• Reaction gas equipment for hydrogen concentrations larger than 4%
• Chiller in case no water cooling is available on-site

Annealing furnace - GLO Technical details

View inside of the annealing furnace:

1. opened door
2. radiation shields
3. ceramic fiber insulation and heating elements
4. charging rack
5. thin metallic sourrounding
6. afterburner
7. frame

The maximum temperature of the GLO annealing furnace is 1100°C. In this temperature range, heat is transmitted via a high amount of heat convection and conduction.

To ensure excellent temperature uniformity, the furnace is equipped with a gas circulation system by means of a ventillator located at the rear of the furnace, which ensures that the sample is surrounded by uniform inert gas at all times.

The sample specimen is placed on an engineered, horizontal charging rack with the incoming gases guided over the sample. Any gaseous by-products generated are immediately flushed out of the furnace.

A probe thermocouple is positioned at the rear of the furnace and in close proximity to the samples. The probe thermocouple serves as the control thermocouple for the two heating zones of the GLO, and simultaneously, monitors the temperature directly at the sample.

The heating elements are located outside of the retort. An over-temperature thermocouple is used for unattended operation. Further thermocouple probes can be integrated into the retort upon request.