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Answer it Forward Challenge
Asked: March 3, 2021In:
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After installing new (sometimes calibrated) thermocouples (i.e. type K/S/R), they start to deviate over time. What can be the cause of that.

temperature deviation
  1. Greg Kimble

    Time and temperature have a way of making things deteriorate.  Vacuum also can present a problem for the materials (constituents) of the thermocouple, specifically relating to the vapor pressure of the materials.

    Time and temperature have a way of making things deteriorate.  Vacuum also can present a problem for the materials (constituents) of the thermocouple, specifically relating to the vapor pressure of the materials.

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Asked: March 1, 2021In:
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cryogenic mediumliquid nitrogen
  1. VacuumFurnaces.com Answers
    This answer was edited.

    Liquid nitrogen cold traps prevent products arising during the equipment operation from passing from the chamber into the pump where they could either contaminate the pump or cause the breakdown of the pump fluid. In either case, severe loss of efficiency and poor vacuum levels result. In the examplRead more

    Liquid nitrogen cold traps prevent products arising during the equipment operation from passing from the chamber into the pump where they could either contaminate the pump or cause the breakdown of the pump fluid. In either case, severe loss of efficiency and poor vacuum levels result. In the example shown the diffusion pump was only capable of reaching 4 x 10-3 Torr rather than the typical 1 x 10-5 Torr range achieved with a clean pump. In addition, these types of cold traps prevent backstreaming of the pump.

    SOURCE: Cold Traps / VAC AERO International Inc.

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Asked: March 1, 2021In:
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evacuationhigh vacuum valve
  1. Answer it Forward Challenge Official Account of VacuumFurnaces.com

    Using the roughing pump to evacuate the vacuum chamber before opening the high vacuum (gate) valve is necessary for several reasons related to vacuum efficiency, protection of equipment, and process integrity: 1. Prevent Overloading the High-Vacuum Pump: High-vacuum pumps, such as turbomolecular orRead more

    Using the roughing pump to evacuate the vacuum chamber before opening the high vacuum (gate) valve is necessary for several reasons related to vacuum efficiency, protection of equipment, and process integrity:

    1. Prevent Overloading the High-Vacuum Pump:
    High-vacuum pumps, such as turbomolecular or diffusion pumps, are designed to operate at low pressures and cannot handle atmospheric pressure or high-pressure environments. Starting with a high chamber pressure could overload the pump, potentially damaging it or drastically reducing its performance.

    2. Maintain Efficiency and Vacuum Quality:
    Roughing pumps (often rotary vane or scroll pumps) are built to handle the initial high pressures in the chamber and can quickly reduce the pressure to a level that high-vacuum pumps can manage efficiently. By using the roughing pump first, the chamber pressure is lowered to a point where the high-vacuum pump can operate effectively without being exposed to excessive gas load.

    3. Protect Sensitive Pump Components:
    High-vacuum pumps contain delicate, high-speed components (like rotor blades in turbomolecular pumps) that are susceptible to damage or wear if exposed to higher pressures. Bringing the chamber down to a low enough pressure with the roughing pump minimizes the stress on these sensitive components, extending their lifespan and reducing the risk of failure.

    4. Minimize Backstreaming and Contamination:
    If the high-vacuum pump is started with the chamber at a high pressure, there’s a greater likelihood of oil backstreaming in oil-sealed systems (e.g., diffusion pumps). Starting with a roughing pump allows a controlled transition to a lower pressure, where the high-vacuum pump can operate without excessive backstreaming risk.

    5. Ensure Process Stability and Product Quality:
    For processes that require stable, high-purity vacuum levels (such as heat treating, coating, or etching), gradual evacuation through the roughing stage reduces contaminants and moisture in the chamber. This provides a cleaner start for the high-vacuum pump, leading to more consistent and reliable results.

    In summary, using the roughing pump first lowers the pressure safely and efficiently, protects the high-vacuum pump from overload, and maintains vacuum quality, which is essential for the performance and longevity of the vacuum system.

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Asked: March 1, 2021In:
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carburizingnitriding
  1. Thomas

    While both procedures have the same end goal of surface hardening components, nitriding and carburizing employ different resources and methods to do so, with different results. Carburizing is a heat treat process that uses carbon, while Nitriding uses nitrogen. Generally, each process diffuses the cRead more

    While both procedures have the same end goal of surface hardening components, nitriding and carburizing employ different resources and methods to do so, with different results. Carburizing is a heat treat process that uses carbon, while Nitriding uses nitrogen. Generally, each process diffuses the chosen element into the surface of the component to produce a more wear resistant or harder surface. Nitriding is a better process for precision components, whereas carburizing may be a better choice for highly loaded coarse components [1]. 

    Nitriding sometimes results in higher costs primarily because of cycle times and batch processing considerations. However, the cost increase typically corresponds to better properties. Another driver of cost is the cost of the base material. Nitrided steels tend to be produced from high alloy steels, which are usually more expensive [2].

    In some cases, the carburizing process may prove more expensive, but the price of the base material (likely high alloy) must also be factored in [1][2].

    [1]-https://blog.metlabheattreat.com/posts/nitriding-and-carburizing/#:~:text=The%20main%20difference%20is%20that,in%20carburizing%2C%20carbon%20is%20used.&text=Ion%20nitriding%2C%20on%20the%20other,is%20a%20more%20restrictive%20process.

    [2]-https://www.eurotherm.com/en/heat-treatment-articles-en/what-is-the-cost-difference-between-carburizing-and-nitriding/#:~:text=For%20Carburized%20steels%20you%20would,processing%20and%20long%20cycle%20times.

     

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Asked: March 1, 2021In:
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ion nitriding nitrocarburizing
  1. Answer it Forward Challenge Official Account of VacuumFurnaces.com

    Ion nitriding and nitrocarburizing make good sense in applications that require enhanced surface hardness, wear resistance, fatigue strength, and corrosion resistance, especially when complex geometries or precise control over the case depth is needed. Here are specific scenarios when these processeRead more

    Ion nitriding and nitrocarburizing make good sense in applications that require enhanced surface hardness, wear resistance, fatigue strength, and corrosion resistance, especially when complex geometries or precise control over the case depth is needed. Here are specific scenarios when these processes are especially beneficial:

    1. When Precise Control Over Case Depth and Surface Properties is Required

    • Ion Nitriding: This process allows precise control over the case depth, hardness profile, and nitrogen content due to its controlled ionization environment. This makes it ideal for applications with stringent requirements on dimensional accuracy or thin, hard cases—such as in aerospace and tooling.
    • Nitrocarburizing: By incorporating both nitrogen and carbon into the surface, nitrocarburizing provides additional benefits like enhanced surface lubricity and wear resistance, making it suitable for applications requiring a very hard surface with some lubricity, such as hydraulic pistons, gears, and camshafts.

    2. For Parts with Complex Geometries

    • Ion Nitriding: The ionized nitrogen atoms in ion nitriding are highly reactive and can penetrate complex geometries, including small holes, threads, and intricate shapes, much more uniformly than in conventional gas nitriding. This makes it effective for complex parts where uniform hardening is critical, such as molds and dies.

    3. When Lower Treatment Temperatures are Advantageous

    • Both ion nitriding and nitrocarburizing can be conducted at relatively low temperatures (typically between 450–600°C), which minimizes the risk of distortion and preserves core properties. This is valuable for precision components, thin-walled parts, and applications sensitive to distortion or requiring high dimensional stability, like bearings and certain precision automotive parts.

    4. For Enhanced Fatigue Strength in High-Stress Applications

    • Ion Nitriding: The process creates compressive stresses on the surface, enhancing fatigue strength. This makes it ideal for components exposed to cyclical loading or high stress, such as crankshafts, camshafts, and gears, especially in high-performance and heavy-duty applications.
    • Nitrocarburizing: Similarly, nitrocarburizing imparts a wear-resistant and fatigue-resistant surface, which benefits components like shafts, spindles, and connecting rods that are subjected to repeated stress.

    5. To Improve Corrosion Resistance

    • Nitrocarburizing: The carbon in nitrocarburizing enhances corrosion resistance along with wear properties. When corrosion resistance is crucial, such as for hydraulic components or outdoor equipment, nitrocarburizing can provide a surface layer that withstands corrosive environments effectively.
    • Ion Nitriding: While not as corrosion-resistant as nitrocarburizing, ion nitriding still provides a significant improvement over untreated steel, which can be useful in applications with moderate exposure to corrosive elements.

    6. For Eco-Friendly and Energy-Efficient Hardening

    • Ion Nitriding: This process is more environmentally friendly compared to some conventional nitriding methods because it doesn’t involve toxic gases like ammonia. Ion nitriding is also energy-efficient due to its precise and efficient plasma control, making it suitable for industries focused on green processes or sustainability.
    • Nitrocarburizing: Often done in a salt bath or gas furnace, nitrocarburizing still offers an alternative to more intensive heat treatments that consume higher energy.

    In summary, ion nitriding and nitrocarburizing are especially useful for precision, low-distortion, wear-resistant, and fatigue-resistant surfaces, particularly on complex parts or in situations where lower processing temperatures are required. They both provide durable, high-performance surface treatments that extend part life in demanding applications across industries like automotive, aerospace, tooling, and hydraulics.

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