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Bryan R Cope
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Asked: 2023-07-21T19:03:34+00:00 In:

Difficulty In Reaching Appropriate Vacuum Level.

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We use Vac Aero furnaces with 6 bar quench to process tool steel and high speed steel.

In the past week, both furnaces have been unable to reach the starting vacuum or loose vacuum during heat treating.

I do have a leak detector and have been using it.  Not finding any significant leaks when the furnace is cold.

I am looking for someone who can give us some hands on insight on what is going on.  I have been overseeing these 2 furnaces for the past 7 years.

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    1 Answer

    1. Official Account of VacuumFurnaces.com
      This answer was edited.

      It sounds like you’re dealing with a tricky vacuum issue. Since you’ve already been leak-checking the furnaces and haven’t found any significant leaks when they’re cold, a few potential factors to consider could be:

      1. Thermal expansion-related leaks: As the furnace heats up, thermal expansion may cause small leaks to appear that aren’t detectable when the furnace is cold. Check for areas where seals or joints might be affected by high temperatures.
      2. Outgassing: Sometimes, when a furnace heats up, materials inside the furnace (including lining materials or residues) can outgas, leading to a loss in vacuum. Cleaning or baking out the furnace may help reduce this.
      3. Pump or valve issues: Since you’re having trouble reaching vacuum or maintaining it, your vacuum pumps or valves may need maintenance or replacement. Have you checked the functionality of your pumps (e.g., diffusion, turbomolecular, or backing pumps)? Pump oil contamination or wear may also cause degraded performance.
      4. Backstreaming of oil: If you’re using oil-based vacuum pumps, backstreaming (where oil vapor moves into the furnace chamber) can degrade vacuum quality. Check the pumps for signs of oil contamination.
      5. Quench systems: If there is an issue with your quenching system (since it uses high pressure), check the integrity of seals and valves related to the quench system as well, as it may interfere with vacuum integrity.

      Regarding hands-on help, you might consider contacting a vacuum furnace manufacturer for troubleshooting or a service technician visit. They have detailed knowledge and can offer specialized support for diagnosing and repairing the problem.

      Alternatively, if you’re looking for local or regional expertise, industrial furnace service providers specializing in vacuum furnaces can assist with diagnostics and repair.

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