Daily maintenance of laboratory graphite vacuum furnace

08-06-2025       Author: KJ technology

The daily maintenance of laboratory graphite vacuum furnaces is a key link to ensure stable operation of equipment, extend service life, and ensure the accuracy of experimental results. We provide a systematic maintenance plan from the aspects of cleaning and maintenance, vacuum system maintenance, heating system maintenance, temperature control system inspection, mechanical structure maintenance, safety protection, and record management.

1. Cleaning and maintenance

Internal cleaning of furnace body

Frequency: After each experiment or every 24 hours of continuous operation.

method:

Use a soft bristled brush or vacuum cleaner to remove residual powder and particles from the furnace, and avoid using hard tools to scrape the graphite inner wall.

For stubborn stains, anhydrous ethanol or acetone can be used for wiping, but it is necessary to ensure complete evaporation before using electricity.

Attention: Wear dust masks and gloves during cleaning to avoid inhaling graphite dust or coming into contact with chemical solvents.

Observation window cleaning

Frequency: Once a week.

Method: Wipe the observation window with a specialized glass cleaner to ensure no oil stains, fingerprints, or scratches, and maintain a clear view.

External surface cleaning

Frequency: once a day.

Method: Wipe the furnace shell with a dry cloth, avoid using corrosive cleaning agents, and prevent damage to the surface coating.

2. Vacuum system maintenance

Vacuum pump maintenance

Oil level check: Check the pump oil level before daily operation to ensure it is between the oil gauge marks. If the oil level is too low, it is necessary to replenish the same model of vacuum pump oil.

Oil quality replacement: Replace with new oil every 200 hours of operation or when the oil quality turns black or cloudy. When replacing, it is necessary to drain the old oil, clean the oil chamber, and then inject new oil.

Cleaning of air intake filter: Check and clean the filter every week to prevent dust from blocking and affecting the air extraction efficiency.

Seal inspection

Frequency: Once a month.

method:

Check whether the sealing rings of the furnace door, flange, observation window and other parts are aging, deformed or cracked.

Apply soapy water to the sealing surface and observe for any bubbles to confirm the sealing performance.

Replacement standard: If the sealing ring has cracks or a compression permanent deformation rate exceeding 30%, it should be replaced in a timely manner.

Vacuum pipeline inspection

Frequency: Once every quarter.

Method: Check if the pipeline connections are loose or leaking, and use a helium mass spectrometer leak detector to detect minor leaks.

Solution: Re tighten or replace the sealing components of the leaking parts, and replace the aging pipelines if necessary.

3. Heating system maintenance

Heating element inspection

Frequency: Once a month.

method:

Visually inspect whether the graphite heating rod and heating wire are broken, oxidized, or deformed.

Measure the resistance value of the heating element with a multimeter and compare it with the nominal value. If the deviation exceeds 10%, it needs to be replaced.

Attention: When replacing the heating element, the power should be turned off to avoid the risk of electric shock.

Tightening of electrode connection

Frequency: Once every quarter.

Method: Check if the connecting bolts between the electrode and the heating element are loose, tighten them to the specified torque with a wrench, and prevent local overheating caused by increased contact resistance.

Graphite protection

method:

Avoid direct contact with metal tools to prevent scratching the surface of graphite.

When not in use for a long time, apply an anti-oxidation coating (such as boric acid solution) on the surface of graphite parts to reduce oxidation losses.

4. Temperature control system inspection

Thermocouple calibration

Frequency: Once every six months.

Method: Compare the thermocouple with a standard thermometer and calibrate it at key temperature points such as 100 ℃, 300 ℃, and 500 ℃. If the deviation exceeds ± 2 ℃, it needs to be adjusted or replaced.

Temperature controller parameter verification

Frequency: Once a month.

Method: Check whether the PID parameters (proportional, integral, derivative) set by the thermostat are consistent with the equipment requirements to avoid excessive temperature fluctuations.

Signal line inspection

Frequency: Once every quarter.

Method: Check whether the signal wires between the thermocouple and the temperature controller are damaged or loose, to ensure stable signal transmission.

5. Mechanical structure maintenance

Lubrication of furnace door hinge

Frequency: Once a month.

Method: Apply high-temperature grease (such as molybdenum disulfide grease) to the hinge to reduce wear and abnormal noise.

Fan maintenance

Frequency: Once every quarter.

method:

Clean the dust on the fan blades to prevent overheating caused by poor airflow.

Check if the fan bearings are short of oil and add lubricating oil to the specified level.

Inspection of transmission components

Frequency: Once every six months.

Method: Check whether the transmission components such as the furnace door lifting mechanism and the material tray moving device are flexible, and adjust the tightness of the belt or chain to the specified range.

6. Security protection

Grounding inspection

Frequency: Once a month.

Method: Use a grounding resistance tester to measure the grounding resistance of the equipment, ensuring it is ≤ 4 Ω to prevent the risk of leakage.

Emergency stop button test

Frequency: Once every quarter.

Method: Press the emergency stop button and confirm that the device can immediately stop running. After resetting, the function will be normal.

Inspection of protective devices

Frequency: Before daily operation.

Method: Check whether the furnace door safety interlock device and over temperature alarm device are sensitive and reliable to ensure the safety of the experiment.

7. Record management

Maintenance log

Content: Record the time, items, replaced parts, and operator information for each maintenance.

Function: To provide historical data support for equipment maintenance, facilitating the tracking of fault causes and optimizing maintenance plans.

Fault file

Content: Record equipment malfunction symptoms, maintenance process, and replaced parts.

Function: Analyze fault patterns and prevent similar problems from occurring in advance.