Precautions for using customized nitrogen vacuum furnace

Customized nitrogen vacuum furnaces must strictly follow operating procedures during use to ensure equipment safety, process stability, and product quality. The following is a classification explanation of key precautions:

1. Preparation before operation
Equipment inspection
Vacuum system: Check if the vacuum pump, valves, and seals are intact to ensure no leaks. For example, using a helium mass spectrometer leak detector to test the sealing of the furnace body.
Nitrogen system: Confirm nitrogen purity (usually ≥ 99.999%), flow meter accuracy, and pipeline connection reliability.
Electrical system: Check whether the heating elements, temperature control instruments, and sensors are normal to avoid short circuits or poor contacts.
Safety device: Test functions such as over temperature alarm, pressure protection, emergency stop button, etc.
Confirmation of process parameters
Set temperature, vacuum degree, nitrogen flow rate, and insulation time based on material characteristics. For example, nitriding treatment requires precise control of nitrogen partial pressure (such as 0.1-10 Torr) and temperature (500-900 ℃).
Before the first use, an empty furnace temperature rise test is required to verify the accuracy of the temperature control system (error should be ≤ ± 5 ℃).

2. Operation process specification
Loading and sealing
The workpiece needs to be clean and free of oil stains to avoid contaminating the furnace. For example, metal workpieces need to be wiped with alcohol and dried.
Avoid blocking the heating element during loading to ensure uniform airflow.
After closing the furnace door, slowly evacuate to the target value (such as 10 ⁻ ³ Torr), and then fill nitrogen to the process pressure.
Heating and atmosphere control
The heating rate should be controlled at 5-10 ℃/min to avoid deformation or cracking of the workpiece caused by thermal stress.
The nitrogen flow rate needs to be stable to avoid pressure fluctuations affecting the process. For example, the fluctuation of nitrogen flow rate during carburizing treatment should be ≤± 5%.
Real time monitoring of temperature, vacuum degree, and gas composition, and immediate shutdown for troubleshooting in case of abnormalities.
Cooling and post-processing
After the process is completed, choose the cooling method based on the material (such as furnace cooling or rapid cooling with nitrogen gas).
Cool to a safe temperature (such as ≤ 80 ℃) before turning on the furnace to prevent burns or oxidation.
Clean the furnace promptly after opening to avoid residue affecting the next use.

3. Safety and Maintenance
safety protection
Operators should wear protective goggles and gloves to avoid high temperature burns or nitrogen suffocation.
Flammable materials are prohibited from being stacked around the furnace body to ensure good ventilation.
Regularly check the pressure of nitrogen cylinders to avoid process interruptions caused by empty cylinder usage.
Equipment maintenance
Daily maintenance: clean the furnace, check the seals, calibrate the temperature sensor.
Regular maintenance: Replace the vacuum pump oil every 3 months and check the aging condition of the heating element every 6 months.
Fault handling:
Insufficient vacuum degree: Check the sealing ring, valve or vacuum pump.
Abnormal temperature: Verify the thermocouple or replace the heating element.
Nitrogen leakage: Use soapy water to detect pipeline joints, tighten or replace seals.

4. Special scenario precautions
High temperature nitriding treatment
High temperature resistant materials (such as graphite and molybdenum) should be used as fixtures to avoid reacting with nitrogen gas.
Strictly control the nitrogen flow rate to prevent excessive thickness or cracking of the nitride layer.
Handling of flammable materials
The furnace needs to be evacuated in advance and filled with nitrogen for multiple replacements to ensure an oxygen content of ≤ 0.1%.
Prohibit the use of oil containing vacuum pumps and switch to dry pumps or molecular pumps.
Long term continuous operation
Stop the machine every 24 hours to check the equipment status and avoid overheating or component fatigue.
Record operating parameters, analyze trends to prevent malfunctions.

5. Record and Trace
Process record
Record the temperature curve, vacuum degree, nitrogen flow rate and other parameters of each operation for easy problem tracing.
Save the correspondence between material batch numbers and process parameters.
Equipment Archives
Establish equipment maintenance logs to record maintenance time, component replacement, and fault handling.
Regularly calibrate instruments (such as once a year) to ensure accurate data.
By strictly following the above precautions, the efficiency of customized nitrogen vacuum furnaces can be significantly improved, equipment life can be extended, and product quality stability can be ensured. Operators need to receive professional training, familiarize themselves with equipment characteristics and emergency response procedures.