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Bryan R Cope
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Bryan R Cope
Asked: July 21, 2023In:
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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 ...

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    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: Thermal expansion-related leaks: As the furnace heats up, thermal expansion may causRead more

    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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Answer it Forward Challenge
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Answer it Forward Challenge
Asked: April 13, 2021In:
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helium leak rate
  1. VacuumFurnaces.com Answers

    The leak-up rate you should be looking for depends primarily on the type of base metals you are trying to braze. As mentioned at the beginning of this article, any air leak into the furnace represents an influx of oxygen into the furnace. Metals vary considerably in their tolerance of oxygen, with nRead more

    The leak-up rate you should be looking for depends primarily on the type of base metals you are trying to braze. As mentioned at the beginning of this article, any air leak into the furnace represents an influx of oxygen into the furnace. Metals vary considerably in their tolerance of oxygen, with nickel and gold being examples of metals that have a large tolerance for the presence of oxygen. That is, they will not oxidize to the point that there is any negative effect on brazing.

    However, other metals, such as chromium, or base metals which contain titanium and/or aluminum in their chemistry, will be highly sensitive to the presence of any oxygen in the furnace. Thus, may I suggest the following as a guideline for vacuum-furnace brazing:

    Tolerable Vacuum Furnace Leak-up Rates:

    • For base metals that contain any titanium or aluminum: less than five (5) microns per hour.
    • For base metals containing chromium (Cr), or manganese (Mn) but no titanium and/or aluminum: less than ten (10) microns per hour.
    • For base metals containing nickel (Ni), gold (Au), etc., but without any Cr or Mn or Ti or Al: less than fifteen (15) microns per hour.>>> READ MORE

    SOURCE: Kay & Assoc. Brazing Consultants

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Answer it Forward Challenge
Asked: February 25, 2021In:
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How do I fix leaks in a vacuum furnace?

leak repair
  1. VacuumFurnaces.com Answers
    This answer was edited.

    Fixing leaks in a vacuum system is crucial to maintain optimal performance and efficiency. Remember to prioritize safety when working with vacuum systems and be aware of the potential hazards associated with vacuum leaks. If in doubt, seek professional assistance. Here are the major steps needed toRead more

    Fixing leaks in a vacuum system is crucial to maintain optimal performance and efficiency. Remember to prioritize safety when working with vacuum systems and be aware of the potential hazards associated with vacuum leaks. If in doubt, seek professional assistance.

    Here are the major steps needed to identify and fix leaks in a vacuum furnace:

    1. Isolate the Furnace.
    2. Tighten Connections.
    3. Perform a Leak Check.
    4. Perform a Vacuum Pump Down Test.
    5. Inspect Seals and Gaskets.
    6. Check Vacuum Hoses and Tubing.
    7. Check Flanges and Connections.
    8. Examine Viewing Ports and Windows.
    9. Inspect Heating Elements.
    10. Examine Vacuum Pump and Valves.
    11. Inspect Insulation.
    12. Check for Welding Defects.
    13. Replace Faulty Components.
    14. Perform a Helium Mass Spectrometry Test.
    15. Follow Manufacturer Guidelines:
      — Refer to the furnace’s manual or documentation for specific guidance on leak detection and repair. The manufacturer may provide recommendations and precautions as well as troubleshooting tips and information on common areas prone to leaks.
    16. Consult manufacturer’s support team:
      — If you are unable to identify or fix the leak, or if the repair involves complex components, it may be advisable to consult with the manufacturer’s technical support or hire a professional technician experienced in vacuum furnace systems.
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