Vacuum Furnace Operation and Maintenance

Proper and correct use of a vacuum furnace is crucial for ensuring reliable operation, protecting personnel and equipment safety, and extending the equipment's service life. Below is a detailed description of the usage and maintenance precautions for vacuum furnaces.

Vacuum Furnace Usage Precautions

Preparations Before Operation

1. Understand the Furnace: Familiarize yourself with the performance and main technical specifications of the vacuum heat treatment furnace.

2. Know the Systems: Understand the working principles and structures of the furnace's systems and major components, such as the workpiece transfer mechanism and heating elements.

3. Learn Auxiliary Equipment: Master the structural principles and operational methods of auxiliary equipment like vacuum pumps and temperature control instruments.

4. Master the Procedures: Be well-versed in the operating procedures of the furnace and the functions of various control buttons and switches.

5. Safety Measures: Know the safety devices on the furnace and the measures to take in emergencies.

6. Daily Maintenance: Be aware of vacuum hygiene and daily maintenance precautions.

Preparations Before Starting the Furnace

1. Internal Cleanliness: Check if the inside of the furnace is clean and meets vacuum hygiene standards.

2. Electrical Connections: Ensure that the electrical connections of the power supply and heating system are in good contact.

3. Insulation Resistance: Measure the insulation resistance between the electrodes and the furnace body to ensure it meets the specified requirements.

4. Thermocouple Placement: Check if the thermocouple is accurately placed and if the polarity of the compensation wires is correct.

5. Instrument Check: Ensure that all temperature control instruments, recorders, and vacuum gauges are in good and accurate condition.

6. Vacuum Pump Oil: Check if the vacuum pump is adequately oiled as per the regulations.

7. Compressed Air and Cooling Water: Ensure that the pressure of the compressed air and the water pressure and temperature of the cooling water meet the requirements.

8. Alarm System: Verify that the safety alarm system is functioning properly.

Precautions During Furnace Operation

1. Follow Procedures: Strictly adhere to the process specifications, including heating rate, heating temperature, holding time, and required vacuum level.

2. Electrical Heating: Only start heating when the vacuum level reaches the specified value.

3. Manage Off-gassing: Slow down the heating rate if the vacuum level drops due to outgassing from the workpiece.

4. Monitor Instruments: Frequently observe the indications of temperature and vacuum gauges, and adjust as necessary.

5. Handle Faults: In case of a fault, cut off the heating power first and continue to evacuate the furnace until the temperature drops to a safe level before inspection and repair.

Vacuum System Operation Precautions

1. Oil Levels: Ensure vacuum pumps are oiled as per regulations and monitor oil levels for timely replacement.

2. Oil Change: Regularly replace the oil in oil booster pumps and oil diffusion pumps.

3. Pump Shutdown: Before stopping the pump, close the valve at the pump's intake to isolate it from the vacuum system and vent the pump to prevent oil backflow.

4. Sequential Operation: Start the mechanical booster pump only when the fore-vacuum pump has reached the specified pressure.

5. Monitor Temperature: Monitor the temperature rise of vacuum pumps, ensuring they stay within permissible limits.

6. Pressure Conditions: Operate oil diffusion pumps under allowed pressure conditions, and close inlet and outlet valves before shutting down.

7. Cooling Water: Ensure that the cooling water circuit is operating normally when vacuum pumps are in use.

Emergency Measures

1. Power Failure During Heating:

1. Turn off the main power.

2. Set all buttons to the off position.

3. Check and close all vacuum valves if necessary, using nitrogen to close them if required.

4. Adjust water flow to cool critical components quickly.

2. Water Supply Failure During Heating:

1. Immediately turn off the power.

2. Switch to a backup water supply.

3. Use water to cool high-temperature areas if no backup is available.

4. Move the workpiece to the cooling chamber and cool with nitrogen.

5. If using a circulating water system, close the main shut-off valve if the system is at a low level and there is a power outage.

Vacuum Furnace Daily Maintenance and Care

1. Post-Operation Vacuum: Maintain a vacuum level below 500 Torr in the furnace after operation.

2. Cleaning: Clean dust and residues inside the furnace with alcohol or gasoline and ensure dryness.

3. Seal Maintenance: Clean sealing structures and vacuum system components with alcohol or gasoline, dry them, and apply vacuum grease before reassembly.

4. External Cleanliness: Regularly wipe the exterior surface of the furnace to keep it clean.

5. Workpiece Preparation: Ensure workpieces are clean and dry before entering the furnace to prevent moisture and contaminants.

6. Fault Handling: Address any issues with transmission components immediately to prevent damage.

7. Lubrication: Regularly oil or replace the oil in mechanical transmission components.

8. Component Maintenance: Follow the technical manuals for the maintenance of vacuum pumps, valves, measuring instruments, and electrical components.

9. Safe Repairs: Perform maintenance work with the power off. If repairs must be done with the power on, ensure the safety of the operators, maintenance personnel, and equipment.