1. Vacuum Requirements in Vacuum Furnace Systems
Vacuum furnaces and heat treatment systems rely on controlled vacuum environments to ensure material purity, uniform heating, and repeatable metallurgical results.
Typical processes include:
- Vacuum brazing
- Vacuum sintering
- Degassing and outgassing treatments
- High-temperature annealing
During pump-down and high-temperature operation, residual gases such as oxygen, nitrogen, and hydrocarbons must be reduced to prevent oxidation and contamination.
Typical pressure ranges:
- Pump-down & roughing stage:
10⁵ Pa → 10⁻¹ Pa (usually monitored by Pirani gauges) - High-vacuum processing stage:
10⁻³ → 10⁻⁶ Torr
Pirani gauges alone are not sufficient in this high-vacuum region.
2. Why Cold Cathode Gauges Are Used
Cold cathode vacuum gauges are well suited for vacuum furnaces because:
- They cover the critical high-vacuum range required before and during thermal cycles
- No hot filament → tolerant to metal vapor and process contamination
- Long service life under continuous industrial operation
Unlike hot cathode ionization gauges, cold cathode gauges do not introduce fragile filaments into harsh thermal environments.
3. Role in Furnace Control Logic
In a typical vacuum furnace control architecture:
- Pirani gauge
→ monitors pump-down and rough vacuum stages - Cold Cathode gauge
→ confirms readiness for high-temperature heating
→ monitors vacuum stability during soak and cooling
The cold cathode signal is often used as a process interlock:
- Heating enabled only after reaching target vacuum
- Alarm triggered if pressure rises during the thermal cycle
4. Integration Considerations
Vacuum interface:
- KF25 standard flange
Electrical interface:
- RJ45
- Analog output or RS232 (mutually exclusive)
Installation:
- No orientation restriction
- Can be mounted directly on furnace chambers or vacuum manifolds
Magnetic field note:
Cold cathode gauges generate internal magnetic fields.
System designers should verify compatibility with nearby sensitive components.
5. Application Boundaries
Cold cathode gauges are not recommended when:
- Absolute pressure accuracy is more critical than trend monitoring
- Ultra-high vacuum (<10⁻⁷ Torr) with strict metrology requirements is required
In such cases, hot cathode ionization gauges or calibrated reference gauges should be considered.
What’s more?
Check our VG-SM225 Cold Cathode Vacuum Gauge
Check another application: Cold Cathode Vacuum Gauge for Thin Film & Coating Systems
Check another application: Cold Cathode Vacuum Gauge for Space Simulation & Environmental Test Chambers
Or
Check our VG-SP205 Pirani Vacuum Gauge