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How do you perform a helium leak test on a vacuum furnace?
I found an informative article about the same topic here: FURNACE LEAKAGE: HOW TO LOCATE SUCCESSFULLY VACUUM LEAKS An excerpt: "The vacuum chamber consists of a steel cylinder (vessel), with an access hatch and a jacket applied to all parts for the circulation of cooling water. Since this is an elecRead more
I found an informative article about the same topic here:
FURNACE LEAKAGE: HOW TO LOCATE SUCCESSFULLY VACUUM LEAKS
An excerpt: “The vacuum chamber consists of a steel cylinder (vessel), with an access hatch and a jacket applied to all parts for the circulation of cooling water. Since this is an electrically powered furnace, with a high-temperature thermal chamber and elastomer sealing gaskets, the water that cools the vessel and the associated components keep each surface at a low temperature (less than 150°C).” Continue Reading >>
Source: TAV Vacuum Furnaces
See lessWhat is a vacuum furnace bakeout?
Bake-out is a process which is meant to remove contaminants from components so that high vacuum can be achieved in treatment, and to prevent impurities. To remove these unwanted compounds, engineers perform bake-outs at various high temperatures (these can range from 120 degrees Celsius up to 400 deRead more
Bake-out is a process which is meant to remove contaminants from components so that high vacuum can be achieved in treatment, and to prevent impurities. To remove these unwanted compounds, engineers perform bake-outs at various high temperatures (these can range from 120 degrees Celsius up to 400 degrees Celsius).
The volatile compounds (such as vapor from components, or external particulate matter from humans or the environment) are driven off of the component during the period of heating. The volatile particles are then removed by the vacuum pump.
References:
Vacuum Bake Out: Its Importance and Implementation
courtesy of Vacuum Science World
https://www.vacuumscienceworld.com/blog/vacuum-bake-out
See lessWhat are the 3 stages of quenching?
The 3 stages of quenching are the Vapor Stage, the Boiling Stage, and finally the Convection stage. These stages are in reference to the interaction between the quenchant and the component being cooled. Vapor Stage: In this stage the super-heated component immediately vaporizes the quenchant. The gaRead more
The 3 stages of quenching are the Vapor Stage, the Boiling Stage, and finally the Convection stage. These stages are in reference to the interaction between the quenchant and the component being cooled. Vapor Stage: In this stage the super-heated component immediately vaporizes the quenchant. The gaseous quenchant now surrounds the component in a thin sheet, and the liquid quenchant is no longer in contact with the component and the heat therefore slowly seeps out of the component by radiation and limited conduction. Boiling Stage: As the vapor insulation degrades and collapses, the component begins to boil the quenchant. Due to the direct contact with the liquid quenchant, cooling occurs quicker than the vapor stage. Eventually, as the heat diffuses into the liquid, the interface temperature drops below boiling and the convection stage begins. This is a similar principle to that which allows this to occur (see video). This is called the Leidenfrost Effect (https://en.wikipedia.org/wiki/Leidenfrost_effect#:~:text=The%20Leidenfrost%20effect%20is%20a,the%20liquid%20from%20boiling%20rapidly.) Convection Stage: Finally, the convection stage occurs after boiling has ceased and the heat can only be transferred by convection. The rate of cooling gradually decays as the system approaches equilibrium. Please see the graphical illustration below.
Image courtesy of Globalspec.com
References: Understanding the Cooling Curve Test by D. Scott MacKenzie courtesy of Thermal Processing Magazine https://www.houghtonintl.com/sites/default/files/resources/article_-_understanding_the_cooling_curve_test_0.pdf
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Why is carburizing less expensive than nitriding?
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.
See lessHow does a vacuum furnace roughing pump work?
The roughing pump is the component that primes the other pumps in series on the vacuum line, evacuating the system until a pressure level is reached at which a booster pump (known as a lobe-type roots pump) can be activated, followed by other types of diffusion, turbo molecular, cryogenic, ionic andRead more
The roughing pump is the component that primes the other pumps in series on the vacuum line, evacuating the system until a pressure level is reached at which a booster pump (known as a lobe-type roots pump) can be activated, followed by other types of diffusion, turbo molecular, cryogenic, ionic and other pumps that can be used when the pressure is reached.
Depending on the flow rate, the pumping system is proportioned in relation to system volume, pumping cycle speed, load degassing and contamination produced by the load (vapors, dust, binders, etc.) in the pump itself. It is for this reason that mechanical strength and wear influence the choice of pump type.
I highly recommend you to read an intersting article (splitted in two parts) about this topic:
Roughing pump in high-vacuum furnaces for beginners [1/2]
Roughing pump in high-vacuum furnaces for beginners [2/2]
See less