The commissioning of a vacuum furnace involves checking vacuum performance, pressure rise rate, heating, and gas backfilling. Here’s a detailed summary:
1. Measurement of Ultimate Vacuum
- The furnace should achieve an ultimate vacuum not less than 6 × 10⁻⁴ Pa.
2. Measurement of Working Vacuum
- At 1000 °C empty furnace condition, the working vacuum should not be less than 2.7 Pa.
3. Pressure Rise Rate Measurement
- Heat the furnace to 1200 °C, then perform sufficient bake-out to remove gases.
- Cool the furnace to below 100 °C and measure the pressure rise rate.
- Required value: ≤ 0.5 Pa/h.
4. Furnace Bake-Out with Power On
- Ensure vacuum is not less than 13.3 Pa.
- Gradually heat the furnace to 1300 °C while maintaining vacuum above 13.3 Pa.
- After sufficient bake-out and degassing, confirm that the pressure rise rate meets the technical requirements.
5. Gas Backfill Adjustment
- When the cooling chamber vacuum is 1.33 Pa, close the vacuum isolation door and cooling chamber vacuum valve.
- Inject nitrogen gas at 0.06 MPa into the cooling chamber within 2.5 seconds.
- Ensure that the heating chamber vacuum does not drop below 670 Pa during this operation.
These steps ensure proper vacuum, degassing, and controlled gas backfill, which are essential for stable and safe furnace operation.