Bogie hearth furnaces equipped with SiC rod heating can be used in the production of technical ceramics, especially for sintering at working temperatures up to 1550 °C. The WHTC product line with especially robust design can hold heavy charges including kiln furniture. The furnace chamber is equipped with a high-quality insulation made of high-temperature fiber blocks. The bogie insulation is structured in several layers of lightweight refractory bricks on the heating chamber side.

The furnace is heated along both sides by vertically installed SiC heating rods. This heating technology permits processes requiring working temperatures above 1350 °C which cannot achieved with wire heating elements. The SiC rods are controlled by thyristor controller which counteract the aging of the heating elements by means of automatic power compensation.

Additional equipment The WHTC bogie hearth furnaces can be equipped with extensive additional equipment to be optimally adapted to individual processes.

• Tmax 1550  °C
• Dual shell housing with rear ventilation, provides for low shell temperatures
• Swing door hinged on the right side
• Heating from both sides via vertically mounted SiC rods
• Thyristor controllers with automatic output compensation counteract the aging of SiC rods
• Multi-layered insulation with high-quality fiber modules on the heating chamber side
• Bogie for heavy loads lined with lightweight refractory bricks
• Bogie hand driven on rubber tires
• Motor-driven exhaust air flap on the furnace roof
• Over-temperature limiter with manual reset for thermal protection class 2, as defined in EN 60519-2, to protect the furnace and charge

The high-temperature chamber furnaces HTC 16/16 - HTC 450/16 are heated by vertically hung SiC rods, which makes them especially suitable for sintering processes up to a maximum operating temperature of 1550 °C. For some processes, e.g. for sintering zirconium oxide, the absence of interactivity between the charge and the SiC rods, these models are more suitable than the alternatives heated with molybdenum-disilicide elements. The basic construction of these furnaces make them comparable with the already familiar models in the HT product line and they can be upgraded with the same additional equipment.

• Tmax 1550  °C
• Dual shell housing with fan cooling for low shell temperatures
• Heating from both sides via vertically mounted SiC rods
• High-quality fiber insulation backed by special insulation
• Side insulation constructed with tongue and groove blocks provides for low heat loss to the outside
• Long-life roof insulation with special suspension
• Chain-guided parallel swivel door for defined opening and closing of the door without destroying the insulation
• Labyrinth sealing ensures the least possible temperature loss in the door area
• Specially reinforced furnace floor for accommodating high charge weights for model HTC 16 and above
• Exhaust air opening in the furnace roof
• Heating elements switched via SCR‘s
• Over-temperature limiter with manual reset for thermal protection class 2 in accordance with EN 60519-2 as temperature limiter to protect the furnace and load

• For additional equipment see models HT 04/16 - HT 450/18

The high-temperature chamber furnaces HT 04/16 - HT 450/18 have proven reliable over many years in the lab and in the production of technical ceramics. Whether for bioceramics, for sintering CIM components or for other processes up to a maximum temperature of 1800 °C, these furnaces afford the optimal solution for the sintering process.

High-temperature chamber furnaces can either be insulated with fiber material or lightweight refractory bricks. Furnaces with fiber insulation achieve significantly shorter heating up times because of the low thermal mass. An insulation made of lightweight refractory bricks (see HFL models on page 35), on the other hand, has the advantage of better chemical stability.

These furnaces can also be tailored to specific processes by means of a wide range of additional equipment. The addition of a debinding package, for example, allows the use of these models as combi furnaces for debinding and sintering in one process. Thermal or catalytic exhaust cleaning equipment round up the system.

• Tmax 1600  °C, 1750  °C or 1800  °C
• Dual shell housing with fan cooling for low shell temperatures
• Heating from both sides via molybdenum disilicide heating elements
• High-quality fiber insulation backed by special insulation
• Side insulation constructed with tongue and groove blocks provides for low heat loss to the outside
• Long-life roof insulation with special suspension
• Chain-guided parallel swivel door for defined opening and closing of the door without destroying the insulation
• Labyrinth sealing ensures the least possible temperature loss in the door area
• Specially reinforced furnace floor for accommodating high charge weights for model HT 40 and above
• Exhaust air opening in the furnace roof
• Heating elements switched via SCR‘s
• Over-temperature limiter with manual reset for thermal protection class 2 in accordance with EN 60519-2 as temperature limiter to protect the furnace and load

Additional equipment

• Customized dimensions
• Controlled cooling system with frequency-controlled cooling fan
• Commissioning of the furnace with test firing and temperature uniformity measurement (also with load) for the purpose of process optimization
• Temperature measurement with thermocouples, types B and type S with automatic pull-out device for precise control results in the low temperature range
• Protection grid in front of the heating elements to prevent mechanical damages
• Special heating elements for zirconia sintering provide for longer service life with respect to chemical interaction between charge and heating elements
• Protective gas connection as well as sealing of the furnace housing to purge with non-flammable protective or reaction gases
• Manual or automatic gas supply system
• Gas supply system in the furnace chamber with ceramic bell jar, protective gas inlet and outlet from below for better sealing when operating with protective gases and/or to prevent from chemical interactions between the load and the insulation or the heating elements
• Parallel swivel door opening upwards, also motor driven
• Bottom insulation made of durable lightweight refractory bricks for heavy charge weights
• Motorized exhaust air flap, switchable via the program
• Debinding package I with passive safety package and monitoring of the underpressure in the furnace chamber, exhaust gas fan, fresh air fan, preset underpressure in the furnace chamber, controlled by Nabertherm controller P 300
• Debinding package II with passive safety concept
• Emergency purging with nitrogen
• Exhaust air and exhaust gas piping
• Thermal or catalytic exhaust cleaning systems
• Process documentation, display and control via HiproSystems control system

The HFL 16/16 HFL 160/17 product line is characterized by its lining with robust light weight refractory bricks. Compared with the fiber-insulated models of the HT product line, these furnaces are recommended when high charge weights have to be sintered. In most cases lightweight refractory brick insulation is also significantly more resistant to gas emissions occurring during heat treatment.

Standard equipment like HT models, except:

• Tmax 1600  °C or 1700  °C
• Sturdy lightweight refractory bricks and special backing insulation
• Furnace floor made of lightweight refractory bricks accommodates high charge weights

Additional equipment like HT models

For charging complex settings we recommend lift-top or lift-bottom furnaces. Also small workparts can be conveniently loaded on different layers. Up to an application temperature of 1500 °C the furnaces are heated by SiC rods (HTC models). For sintering temperatures above 1500 °C these furnaces with molybdenum disilicide heating elements (HT models). Possible potential chemical interaction between the charge and the heating method can also affect the selection of heating system.

The basic furnace comes with one table. Depending on the technical requirements are equipped, a lift-top or lift-bottom version will be the choice. The system can be expanded with one or more changeable tables, either manually or electrically driven. Other additional equipment, like controlled cooling systems to short process cycles or the addition of a debinding package for debinding and sintering in one process provide for tailored solution for individual needs.

• Tmax 1400  °C or 1500  °C (HTC models with SiC rod heating)
• Tmax 1600  °C, 1750  °C or 1800  °C (HT models with molybdenum disilicide heating elements)
• Dual shell housing with fan cooling provides for low shell temperatures
• Designed as lift-top furnace with driven hood (LT) or lift-bottom furnace
• Gently running, low-vibration spindle drive or electrohydraulic drive for larger models
• Safe and tight closing of the furnace due to labyrinth seal and sand cup
• Heating from all four sides provides for good temperature uniformity
• High-quality fiber insulation backed by special insulation
• Side insulation constructed with tongue and groove blocks provides for low heat dissipation to the outside
• Long-life roof insulation with special suspension
• Furnace table with special bottom reinforcement to accommodate high charge weights
• Motor-driven exhaust air flap in the furnace roof, switchable at the program
• PLC controls with state-of-the-art touch panel as user interface
• Over-temperature limiter with manual reset for thermal protection class 2 in accordance with EN 60519-2 as temperature limiter to protect the furnace and load

Additional equipment

• Customized dimensions
• Controlled cooling system with frequency-controlled cooling fan
• Commissioning of the furnace with test firing and temperature uniformity measurement (also with load) for the purpose of process optimization
• Temperature measurement with thermocouples, types B and type S with automatic pull-out device for precise control results in the low temperature range
• Heat from all sides and between the stack to optimize temperature uniformity
• Protective gas connection as well as sealing of the furnace housing to purge with non-flammable protective or reaction gases
• Manual or automatic gas supply systems
• Gas supply system in the furnace chamber with ceramic bell jar, protective gas inlet and outlet from below for better sealing when operating with protective gases and/or to prevent from chemical interactions between the load and the insulation or the heating elements
• Alternative table changing systems
• Debinding package I with passive safety package and monitoring of the underpressure in the furnace chamber, exhaust gas fan, fresh air fan, preset underpressure in the furnace chamber, controlled by Nabertherm controller P 300
• Debinding package II with passive safety concept
• Emergency purging with nitrogen
• Exhaust air and exhaust gas piping
• Automatic changing system for thermocouple type S/B for precise measurement and control quality at lowes temperatures, e.g. in combination with a debinding package
• Thermal or catalytic exhaust cleaning systems
• Process documentation, display and control via HiproSystems control system

The gas-fired high-temperature furnaces of the HTB product line are specially developed for applications requiring fast heating up ramps. Gas-fired furnaces are preferred also if inflammable gases are produced in large amounts during the process. A large content of the gas emissions are already burned in the furnace chamber, so that downstream equipment like thermal and catalytic exhaust cleaners can accordingly be downsized. The furnaces are insulated with highly heat-resistant and long-life lightweight refractory brick insulation or fiber materials.

• Tmax 1600  °C
• Customized furnace dimensions
• Powerful, sturdy high-speed burners with pulse control and special flame guidance in the furnace chamber provide for good temperature uniformity
• Operation with natural gas, propane or liquified gas
• Fully automatic PLC control of the temperature, including monitoring of the burner function
• Gas fittings according to DVGW (German Technical and Scientific Association for Gas and Water) with flame monitoring and safety valve
• Reduction-resistant fiber insulation with low heat storage provides for short heating and cooling times
• Dual shell housing provides for low outside temperatures
• Exhaust hood with fittings for further discharge of the exhaust gases
• PLC control with touch panel as user interface

Additional equipment

• Automatic lambda control to set the furnace atmosphere
• Debinding package for debinding and sintering with corresponding safety technology
• Exhaust air and exhaust gas piping
• Recuperator burners
• Thermal or catalytic exhaust cleaning systems
• Process display and documentation via Nabertherm Control Center (NCC)