Six Key Points for Daily Maintenance of Vacuum Furnaces and 20 Fault Treatment Methods

Routine maintenance

For pumps with gas-pressurized features, they should be inspected before daily furnace startups and operated for 30 minutes as necessary to expel moisture from the pump oil.

Regularly inspect the pressure of the cooling water, compressed air, and hydraulic systems, as well as the flow of the cooling water.

Before closing the furnace door, the rubber sealing parts of the furnace door and flange surface should be checked; there should be no sand particles or debris. Use a clean cloth to wipe the rubber sealing rings and flange surface, then evenly apply vacuum grease before closing the door.

4. All workpieces must be cleaned before entering the furnace. After oil quenching, the oil-soaked trays and conveying components should be thoroughly cleaned of all oil.

5. Air-cooled motors are generally commonly used, and they cannot be started under vacuum; they must be inflated first before they can be activated, and an electrical interlock protection device should be in place.

6. The Roots pump should only be started at a vacuum of 133Pa or higher, and should also be equipped with an electrical interlock protection device.

Additionally, for pipelines with compressed air, the drain valve should be opened daily to release accumulated water. Regularly monitor the normalcy of the water temperature indicators for the incoming and outgoing cooling water, and frequently check for any abnormal local temperature increases in areas such as the touch electrode connections, furnace doors, and transformer cooling water pipes.

Fault Phenomenon, Causes, and Solutions

Low vacuum level:Oil contamination, insufficient, or too thin oil, clean the vacuum pump, replace with new vacuum pump oil.

2. Insufficient evacuation timeExtend suction time.

3. Vacuum Filter ClogClean or replace the exhaust filter.

4. Gas leakage area:Ensure power is turned off after downtime, check for any leaks in the electromagnetic valve, pipe joints, vacuum pump suction valve, and sealing gaskets around the work area.

Loud noise:Vacuum pump couplings worn or cracked, replacement required.

6. Exhaust filter clog or misaligned installation position:Clean or replace the exhaust filter and install it correctly.

7. Vacuum Pump Oil InjectionThe O-ring of the suction valve has come loose. Remove the vacuum tube from the pump nozzle, detach the suction nozzle, take out the spring and the suction valve, gently stretch the O-ring a few times, and then reinsert it into the groove. Reassemble as usual.

8. Vane WearReplace the spiral blades.

9. Vacuum Pump Oil LeaksThe return oil valve is clogged. Remove the return oil valve and clean it (refer to the manual for details).

Window Oil LoosenessAfter draining the oil, remove the oil window and wrap it with raw material tape or thin plastic film.

Vacuum pump emits excessive smoke.If vacuum filters are clogged or contaminated, clean or replace the exhaust filters.

12. Pump Oil Contamination:Replace with new oil.

13. Return Oil Valve CloggingClean the return oil valve (refer to the manual).

14. Non-HeatingHeating rod burned out; replaced with a new heating rod.

15. Heating time relay burned out(Both lights turn on simultaneously upon startup, with the OMRON light in yellow): Replace the time relay.

16. Heating line breaksHeated line replaced and securely installed. Control heating temperature band switch poor contact: Repair or replace. AC contactor for heating does not reset: Repair (blow away foreign objects with air flow) or replace.

17. The Heat Continues:Thermal time relay contacts are malfunctioning or burned out; adjust the contact between the time relay and the socket or replace it.

18. Misaligned, loose, or unsealed closures:The steel box has deformed; the heating time and temperature for the steel box were not adjusted properly. Adjustments have been made to the appropriate settings.

19. Excessive time for motor reversalInterchangeable power lines for any two phases (earth wire excluded).

20. Inadequate pressure line ventilationStreamline and pressure the gas conduit.