Daily maintenance of crucible furnace

The daily maintenance of crucible furnace is the key to ensuring its long-term stable operation, extending its service life, and ensuring operational safety. From the dimensions of furnace cleaning, crucible maintenance, electrical system inspection, safety device testing, and operating environment optimization, the core points and operational suggestions for daily maintenance are systematically summarized as follows:

1. Furnace cleaning and residue treatment
a. Furnace cleaning
Frequency: Clean immediately after each use to avoid residue solidification or corrosion of the furnace.
method:
Physical cleaning: Use a high-temperature resistant scraper or soft bristled brush to remove oxides, slag, and other attachments on the inner wall of the furnace.
Chemical cleaning: For stubborn oxides, dilute hydrochloric acid or specialized furnace cleaning agents can be used (ensuring compatibility with furnace materials), thoroughly rinsed and dried after cleaning.
Taboo: It is strictly prohibited to use sharp metal tools to scrape the furnace to avoid damaging the refractory materials.
b. Crucible residue treatment
Classification cleaning: Select cleaning method based on crucible material and residue properties:
Graphite crucible: Blow with compressed air or wipe with a soft cloth to avoid the carbonization layer falling off due to water washing.
Ceramic crucible: can be washed with water and dried, but it is necessary to prevent cracking caused by sudden cooling.
Metal residue: Use a specialized tool to remove it to prevent residue from corroding the crucible.

2. Crucible maintenance and lifespan management
a. Appearance inspection
Inspection content:
Cracks: Visually or using a magnifying glass to inspect the surface and bottom of the crucible for any microcracks.
Deformation: Measure the diameter and height of the crucible, compare it with the standard size, and determine whether it is deformed due to thermal stress.
Erosion: Check whether the inner wall has pits or perforations due to material corrosion.
b. Usage records and lifespan tracking
Record content:
The temperature, time, material type, and weight used each time.
Accumulated usage of the crucible (for example, graphite crucibles are recommended to be replaced after 50-100 uses).
Replacement standard:
When cracks, severe deformation, or erosion depth exceed one-third of the wall thickness, replacement is necessary.

3. Electrical system inspection and maintenance
a. Heating element inspection
Resistance wire:
Check for any signs of breakage, oxidation, or poor contact.
Regularly measure the resistance value and compare it with the factory value. If the deviation exceeds 10%, it needs to be replaced.
Induction coil:
Check if the insulation layer is damaged to avoid the risk of short circuit.
Clean the dust on the surface of the coil to prevent local overheating.
b. Temperature control system calibration
Calibration cycle: Calibrate every 3 months or after replacing the thermocouple.
method:
Compare the actual temperature inside the furnace with the displayed value using a standard thermometer, such as a platinum resistance thermometer.
Adjust PID parameters to ensure temperature fluctuations are within ± 1 ℃.
c. Power and Circuit Inspection
Grounding test: Use a grounding resistance tester every month to check the grounding resistance and ensure it is ≤ 4 Ω.
Line insulation: Check whether the power and control lines are damaged or aged, and the insulation resistance should be ≥ 1M Ω.

4. Safety device testing and functional verification
a. Overtemperature protection device
Testing method:
Simulate overheating conditions (such as artificially increasing the set temperature), observe whether an alarm is triggered and the power is cut off.
Record the deviation between the trigger temperature and the set value, which should be ≤ 5 ℃.
Reset operation: After troubleshooting, reset the protective device according to the instructions. Short circuiting or shielding is strictly prohibited.
b. Leakage protector
Testing cycle: once a month.
Method: Press the “Test” button to confirm that the leakage protector can cut off the power supply within 0.1 seconds.
c. Furnace door interlocking device
Functional verification:
When opening the furnace door, check if the heating power supply automatically cuts off.
After closing the furnace door, confirm that a manual reset is required to restart the heating.

5. Operating environment and maintenance of auxiliary equipment
a. Ventilation system
Filter cleaning:
Clean the ventilation ducts and filters monthly to prevent dust accumulation from affecting heat dissipation.
Check if the fan is running normally, without any abnormal noise or vibration.
Gas pipeline:
Check for leaks in inert gas or vacuum pipelines, and apply soapy water to the interface for inspection.
b. Sealing performance of furnace body
Sealing ring inspection:
Check the furnace door sealing ring monthly for aging, deformation, or damage.
When replacing the sealing ring, choose a product that is consistent with the original factory specifications.
a fastening:
Check if the furnace bolts are loose, especially in high-temperature areas, to prevent air leakage caused by thermal expansion.

6. Spare parts management and preventive maintenance
a. Spare parts reserve
Key spare parts list:
Crucibles (classified and stored according to material and specifications).
Heating elements, thermocouples, sealing rings, fuses and other vulnerable parts.
Inventory management:
Establish a spare parts ledger to record the time, quantity, and usage of inventory.
First in, first out to avoid expired spare parts.
b. Preventive Maintenance Plan
draw up a plan:
Develop annual, quarterly, and monthly maintenance plans based on equipment usage frequency and operating conditions.
Clearly define the maintenance project, responsible person, timeline, and acceptance criteria.
Execution and recording:
After maintenance is completed, fill out the “Equipment Maintenance Record Form” and archive it for future reference.
Conduct root cause analysis on issues identified during maintenance and develop improvement measures.

7. Operator training and safety awareness enhancement
a. Regular training
Content:
The structure, principle, and operating procedures of a crucible furnace.
Daily maintenance points and common troubleshooting.
Safety protection knowledge and emergency plan drills.
Form:
Combining theoretical lectures with practical exercises.
Organize a refresher training and assessment every six months.
b. Safety culture
Promotion and Education:
Post safety warning signs and maintenance process diagrams in the operating area.
Case analysis will strengthen security awareness.
Incentive mechanism:
Reward personnel who strictly adhere to maintenance standards and promptly identify potential hazards.
Hold accountable those who violate regulations and cause accidents.

8. Summary and Suggestions
a. Core principles
Prevention first: eliminate hidden dangers through daily maintenance and avoid equipment running with problems.
Standardized operation: Strictly follow the instructions and maintenance manual to eliminate empiricism.
b. Key indicators
Equipment integrity rate: target ≥ 98%, reduce downtime due to malfunctions through regular maintenance.
Maintenance cost: Extend the service life of spare parts and reduce unit usage costs through scientific management.
c. Technological upgrade
Intelligent monitoring: Introducing sensors such as temperature, pressure, and vibration to monitor equipment status in real-time.
Remote diagnosis: Implementing remote fault warning and maintenance guidance through IoT technology.
Through systematic daily maintenance, the reliability, safety, and economy of crucible furnaces will be significantly improved, providing strong support for production.