PRODUCT CATEGORIES

Vacuum Heat Treatment Furnace

Vacuum Sintering Furnace

Vacuum Brazing Furnace

Vacuum furnace manufacturers tell you the common methods of cleaning vacuum brazing furnaces

Oven Dry Run Cycle: This is a standard practice that involves heating the furnace without a load to burn off contaminants. According to the vacuum furnace maintenance procedure, it is recommended to heat the furnace to at least 1200°C (2200°F) and hold it for 30-60 minutes. However, for vacuum brazing furnaces that are vacuum brazing oil cooler products, the operating temperature is usually lower (about 1100-1120°C), so the cleaning temperature needs to be adjusted accordingly. Studies have shown that the cleaning temperature is usually about 38°C (100°F) higher than the maximum operating temperature. For example, if the maximum brazing temperature is 1120°C, the cleaning temperature is generally 1160°C. Always place a stainless steel plate in the furnace. Let the contaminants adsorb to the surface of the stainless steel plate.

How to run a purge cycle in a vacuum furnace?
If the maximum process temperature is less than 1038°C (1900°F), the purge temperature should be at least 1150°C (2000°F). However, for vacuum brazing furnaces, this high temperature may not be applicable, and a lower purge temperature such as 1120°C is recommended, depending on the design of the vacuum brazing furnace. Auxiliary gas: During the temperature rise phase, nitrogen or argon partial pressure can be used to maximize heat transfer and prevent contaminants from entering the diffusion pump. Leak test: After the purge cycle, a leak test is performed to ensure the integrity of the vacuum system. Depending on the cleaning of the contaminated vacuum furnace, this usually involves isolating the heating chamber (i.e., not evacuating) for one hour and measuring the increase in vacuum level (if any). 0.2-0.5Pa per hour for a single chamber vacuum furnace is considered an acceptable leak rate. Visual inspection: After cooling, open the furnace door and visually inspect the cleanliness and mechanical integrity of the heating elements and hot zone components. Check for cracks, ablation or other signs of damage, and perform a component-to-ground resistance check to confirm normal (usually 87-110 ohms).
Treatment of specific pollution: For carbon pollution or flux residue, additional cleaning methods may be required. For example, the strange case of part contamination in vacuum furnaces mentioned that graphite heating elements may release carbon particles due to contact, and it is recommended to regularly check and replace aged graphite parts. Mechanical cleaning: If the contamination is stubborn and the furnace design allows, the furnace may be opened and the interior wiped with an appropriate cleaner. For example, the preventive maintenance of titanium alloy vacuum brazing furnaces recommends ultrasonic dry ice cleaning of molybdenum heaters. Dry ice cleaning of graphite heaters in vacuum brazing furnaces for stainless steel oil coolers, or dragging out the heating chamber of vacuum brazing furnaces. After decomposition, clean with deionized water or methanol, and then bake to remove residual moisture. Now the latest vacuum brazing furnace cleaning process is to use dry ice cleaning equipment such as: using dry ice (solid carbon dioxide) cleaning as the main cleaning medium, through surface blasting cleaning, can achieve non-destructive cleaning effect, and realize automatic cleaning dry ice cleaning machine. Regular cleaning of vacuum brazing furnaces can not only ensure the normal operation of equipment and personal and property safety, but also can greatly save costs, which is a routine operation to improve efficiency.

Special Considerations for Baking Ovens in Vacuum Brazing Furnaces
Aluminum vacuum brazing furnaces typically operate at lower temperatures (595-620°C), unlike high-temperature brazing furnaces or other vacuum furnaces such as those used for vacuum annealing or vacuum sintering. Therefore, the temperature of the high-temperature bake cycle needs to be adjusted to avoid damage to the furnace. According to the operation of the aluminum vacuum brazing furnace, it is common to heat to 700°C for preheating under vacuum conditions, but the bake cleaning cycle may not require such a high temperature. The recommended cleaning temperature is the operating temperature plus 38°C, depending on the maximum tolerance temperature of the vacuum brazing furnace. The cleaning of aluminum vacuum brazing furnaces requires care, and the magnesium in the furnace wall of the aluminum vacuum brazing furnace is easy to burn during the magnesium process. In addition, an advantage of vacuum brazing is that no flux is required, thereby reducing the risk of contamination. According to the vacuum brazing furnace, vacuum brazing avoids complex flux cleaning procedures and reduces production costs, but regular maintenance is still required to deal with any residues.

Frequency and Precautions
The frequency of dry running cycles depends on production volume and contamination levels. According to the maintenance procedures for vacuum furnaces, it is recommended to perform a dry run cycle at least once a week, especially before processing easily contaminated materials (such as titanium alloys) or critical workloads. In addition, preventive maintenance includes regular inspections for leaks, locating small leaks using a helium leak detector, and recording common leak locations for preventive measures. Manufacturer Guidelines and Limitations Always refer to the maintenance manual provided by the manufacturer for detailed guidance on specific furnace models. For example, maintenance of vacuum heat treatment furnaces emphasizes that maintenance activities must consider the integrity of the vacuum system, and any leaks will affect the operating vacuum level and final product quality. It should be noted that some furnaces may not be able to withstand cleaning temperatures higher than the operating temperature, so users should consult the manufacturer to avoid damage. In addition, for furnaces with better sealing designs, mechanical cleaning may be impractical and rely on high temperature bake-out cycles.

Conclusion
The contamination treatment of vacuum brazing furnaces mainly relies on a high temperature bake-out cycle, heating the furnace to about 38°C higher than the normal operating temperature and maintaining it for 30-60 minutes to burn off the contaminants. After completion, a leak test and visual inspection are performed to ensure vacuum integrity. For low temperature and brazing furnaces, the cleaning temperature needs to be adjusted according to the furnace design and may be within the design range. Regular maintenance and following the manufacturer’s guidelines are key to extend the furnace life and maintain high processing quality. Through the above measures, enterprises can effectively reduce product scrap rate, improve product quality and equipment utilization, and ensure the stable operation of vacuum furnace systems under various complex working conditions.

Vacuum Brazing Furnace