Temperature abnormalities in a vacuum sintering furnace may include high-temperature alarms or failure to reach the set temperature. The troubleshooting steps are as follows:
- Check the thermostat parameters
- Verify that the temperature control settings in the furnace work area are normal. Compare with parameters from other properly functioning thermostats.
- Check the solid-state relay (SSR)
- Using the circuit diagram, inspect the SSR in the affected work area.
- Method: Power off the furnace, then measure the resistance between the SSR output terminals with a multimeter.
- A normal SSR shows a resistance of several megaohms or higher.
- If the SSR is shorted (almost zero resistance), it must be replaced with a new one of the same type.
- Check the thermocouple
- With power on, gently move the thermocouple probe in the affected work area.
- If the temperature reading fluctuates widely, the thermocouple contact is poor and must be replaced.
- If the furnace temperature is too low (below set value)
- Inspect the thermocouples in the affected area for damage.
- Test by connecting the thermocouple to a thermostat and checking the displayed temperature.
- Replace any defective thermocouples.
- Check the heating element
- If the thermostat and thermocouples are fine, test whether the heating element is operating normally.
- With power on, follow the circuit diagram to energize the heating element and use a tester to check for voltage at the element’s terminals.
- If voltage is present, measure the current between zones to ensure it is within normal limits.
- If no voltage is present, inspect the furnace circuit according to the wiring diagram to locate blown components or disconnections.