Common Furnace Chamber Issues in Atmosphere Furnaces and Their Solutions

The furnace chamber plays a crucial role in ensuring the stable and efficient operation of an atmosphere furnace. In real industrial and laboratory applications, various problems may arise during use, especially during initial startup or prolonged high-temperature conditions.

At Brother Furnace, we have accumulated years of experience in furnace manufacturing and customer support. Below are some common furnace chamber issues you may encounter and practical solutions to address them.

Furnace Chamber Turns Black at Temperatures Below 1000 °C

Problem Description

When a new furnace is heated below 1000 °C, the surface of the furnace chamber turns black.

Cause

• The chamber is contaminated by organic volatiles.

• Since the chamber is fully sealed and the insulation material is made of alumina-silicate fiber, the organic components cannot be discharged easily.

Solution

• Perform high-temperature firing to burn out volatile organic matter.

• Alternatively, open the furnace door slightly and carry out an “empty firing” to exhaust residual gases.

• Ensure the furnace is well ventilated during the burn-out process.

Liquid Dripping from Furnace Door After Use

Problem Description

After use, liquid seeps from the furnace door area.

Cause

• High moisture content in the furnace chamber.

• Volatile tar-like substances evaporate from the workpieces.

• Moisture is present in the process gas (e.g., nitrogen).

Solution

• For new furnaces, perform empty firing to remove moisture before use.

• Increase the gas inlet flow to flush out volatile components through the exhaust port. (Be careful to avoid blockage.)

• Use high-purity process gases with low moisture content.

Furnace Door Cracking at the Inclined Joint

Problem Description

The furnace door develops cracks at the inclined sealing area.

Cause

• Uneven shrinkage caused by a large temperature difference between the inner and outer door surfaces.

Solution

• Redesign the furnace door structure using a vertical strip assembly to better accommodate thermal expansion.

• Reduce temperature gradients during heating and cooling cycles when possible.

Water Stains Appearing During Hydrogen Atmosphere Bake-Out

Problem Description

Although the hydrogen furnace is baked at 300 °C before shipment, a large amount of water stains appear when the customer bakes the furnace on site.

Cause

• Moisture is absorbed during transport and storage.

• Hydrogen itself may contain trace moisture if not fully purified.

Solution

• Re-bake the furnace thoroughly at the site before operation.

• Check and ensure the hydrogen supply meets high-purity requirements.

Vacuum cannot Be Reached Without Extra Force on the Handwheel

Problem Description

The furnace cannot reach the expected vacuum level unless the handwheel is tightened with a tool.

Cause

• Furnace door deformation leads to poor sealing performance.

Solution

• After welding, perform stress relief treatment on the door to minimize deformation.

• Regularly inspect the sealing surface for flatness and wear.

• Avoid overtightening, which may worsen deformation over time.