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Why must the cryogenic medium used to cool the cold trap between the gas manifold and the mechanical pump be liquid nitrogen?
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 (Fig. 1) or cause the breakdown of the pump fluid. In either case, severe loss of efficiency and poor vacuum levels result. In tRead 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 (Fig. 1) 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.>>>READ MORE
SOURCE: VAC AERO International Inc.
See lessWhat are some common vacuum furnace pumping system failures and their solutions?
For the many vacuum furnaces in use around the world, the vacuum pumping system is a critical component. To get the best value from the vacuum furnace system and to extend its useful life, the regular and careful maintenance of the various vacuum pumps is of utmost importance. Here are two resourceRead more
For the many vacuum furnaces in use around the world, the vacuum pumping system is a critical component. To get the best value from the vacuum furnace system and to extend its useful life, the regular and careful maintenance of the various vacuum pumps is of utmost importance.
Here are two resources that delve deeply into this question, courtesy of Solar Atmospheres and Bill Jone.
This PDF published by Solar Atmospheres Inc. and a Youtube Video presented by the legendary founder of Solar Atmospheres, Bill Jones
SOURCE: Solar Atmospheres Inc. https://solaratm.com/
See lessWhat are acceptable helium leak rates?
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:
SOURCE: Kay & Assoc. Brazing Consultants
See lessWhat is an AMS2750 calibration survey?
Our blog post takes a short look at the AMS2750E standard, with a special focus on the requirements set for calibration, calibration accuracy, and test/calibration equipment. The AMS2750E is predominantly designed for heat treatment in the aerospace industry. Heat treatment is an essential process fRead more
Our blog post takes a short look at the AMS2750E standard, with a special focus on the requirements set for calibration, calibration accuracy, and test/calibration equipment. The AMS2750E is predominantly designed for heat treatment in the aerospace industry. Heat treatment is an essential process for many critical parts of an airplane, so it is understandable that there are tight regulations and audit processes set. While the results and success of some other industrial processes can be relatively easily measured after the process, this is not the case in a heat treatment process. Therefore, very tight control and documentation of the heat treatment process are essential to ensure the quality of the end products.>>>READ MORE
Source: Beamex Blog for Calibration Professionals
See lessHOW CAN I CELANİNG CONTAMİNATİON OF VACUUM FURNACES?
"When operating vacuum furnaces, situations may arise in which the hot zone and/or cold walls may become contaminated (Fig. Nos. 1 – 2). This can occur from a variety of sources: air leaks, outgassing from residues left on the parts as a result of the manufacturing or cleaning processes, vaporizatioRead more
“When operating vacuum furnaces, situations may arise in which the hot zone and/or cold walls may become contaminated (Fig. Nos. 1 – 2). This can occur from a variety of sources: air leaks, outgassing from residues left on the parts as a result of the manufacturing or cleaning processes, vaporization of sensitive materials (e.g., chromium-bearing materials), process-induced contaminations such as carbon in the form of soot or tar, fluxes from brazing pastes, excess braze alloy as well as many other sources. Often times the work being processed is also affected (Fig. 3). The question becomes, how do we attempt to clean up our contaminated vacuum furnaces? >>>Read More
Source: VAC AERO International
See lessHow does a diffusion pump work?
I have provided a diagram above to aid in this answer. The diffusion pump is a very common mechanism for creating a high vacuum. Generally, the pump contains three cone-shaped pressure jets stacked vertically. There is pump oil at the bottom that is heated until it reaches a gaseous state. InRead more
I have provided a diagram above to aid in this answer. The diffusion pump is a very common mechanism for creating a high vacuum. Generally, the pump contains three cone-shaped pressure jets stacked vertically. There is pump oil at the bottom that is heated until it reaches a gaseous state. In the gaseous state, the oil will travel upward and exit through pressure jets in a downward direction. As the vapor travels towards the walls, it will trap air molecules that enter the pump through diffusion. With the cooling coils on the walls, the vapor will immediately condense, releasing the trapped air molecule at a lower position. The oil will travel back to the heater where the process will continue, and the air molecule will be removed via the backing pump and thus creating the high vacuum.
See lessNumber of SAT Thermocouples Required
According to paragraph 3.4.1.2. of AMS2750G: "The SAT shall be performed on all control and recording systems required by the applicable instrumentation type, as well as any additional recording systems used for parts and raw material acceptance in each control zone of each piece of thermal processiRead more
According to paragraph 3.4.1.2. of AMS2750G:
“The SAT shall be performed on all control and recording systems required by the applicable instrumentation type, as well as any additional recording systems used for parts and raw material acceptance in each control zone of each piece of thermal processing equipment used for production heat treatments.”
That means you should perform SAT on all control temperatures as well as any other temperature measurement system which are required by instrumentation type. For example Load thermocouples for instrumentation type A and B.
SAT is not required for overtemp systems (if overtemp protection is the only function of that system).
Each of those ‘systems’ (Thermocouple, TC wires, feedthroughs, and measuring/recording instrument) should be within SAT tolerance (which is 2F for class 1 equipment) to their SAT sensor.
See lessBurn in cycle for new hot zone
Furnace burn out (a.k.a. thermal cleaning) cycles are important part of vacuum furnace maintenance. It is meant to reduce and outgas contaminants inside the heating zone and within the insulation. For new hot zone it is more related to drying, conditioning and outgassing the remaining resin from insRead more
Furnace burn out (a.k.a. thermal cleaning) cycles are important part of vacuum furnace maintenance. It is meant to reduce and outgas contaminants inside the heating zone and within the insulation.
For new hot zone it is more related to drying, conditioning and outgassing the remaining resin from insulation manufacturing processes. Every new furnace should be burned out at it’s nominal temperature and I’d say this rule should also apply to any hot zone replacement. Your hot zone supplier should be able to tell you the nominal temperature of the hot zone.
Duration of burnout should be at least 2 hours at the temperature, however you may keep it longer if you see continuous improvement of furnace vacuum level.
Slow cooling is recommended after burnout.
IMPORTANT: The burn-out cycle is always performed with empty furnace. any tooling / fixturing and other equipment must be removed otherwise serious damage of furnace and tooling may occur.
See lessFor your own safety you should follow the OEM manuals.
What does it mean when a unit of measurement is raised to a negative power?
When a number is raised to a negative power, in fraction form it would be described as one over that number and its exponent (positive). See below: This is also how negative powers work when applied to units. The well known constituent units of the Newton (Force) kg*m/(s^2) could also be written asRead more
When a number is raised to a negative power, in fraction form it would be described as one over that number and its exponent (positive). See below:
This is also how negative powers work when applied to units. The well known constituent units of the Newton (Force) kg*m/(s^2) could also be written as kg*m*s^-2, and so on. The negative exponent would represent the ‘per’, e.g. kilograms meters ‘per’ second squared.
See lessWhat are the benefits of argon gas quench?
ARGON is an inert gas used in gas quenching, thus it has certain inherent advantages over liquid quenching media. Namely: Gas quenched materials have cleaner surfaces and experience less oxidation [1] Gas quenching allows for less deformities and more uniform cooling [1] Gas quenching is safer [2] GRead more
ARGON is an inert gas used in gas quenching, thus it has certain inherent advantages over liquid quenching media. Namely:
There are other gas quenching media, however. One (popular) gas is nitrogen. Nitrogen is more often used because it is cheaper with a faster cooling rate [3].
However, nitrogen can decarburize [3] or nitride [4] sensitive steels, whereas argon does not. Furthermore, when compared directly to nitrogen over a handful of samples, in most cases, argon quenched steel had slightly or significantly better mechanical properties [3].
References
[1] https://www.generon.com/nitrogen-quenching-system/
[2] https://www.lindeus.com/industries/manufacturing-and-materials-processing/gas-quenching-and-inerting
[3] https://www.industrialheating.com/articles/93972-comparing-argon-and-nitrogen-cooling-in-vacuum-furnaces
[4]https://www.boconline.co.uk/en/images/Principles%20of%20Quenching%20and%20Cooling_tcm410-114391.pdf
See lessAre vacuum furnace leak rates linear?
Leak rates are not typically linear in nature.
Leak rates are not typically linear in nature.
See lessWhat is the working principle of a momentum transfer pump?
A transfer pump is used to transfer various gases and liquids from one position to another position. This type of pump moves fuel from a container to a nozzle or from one tank to another so that it can be distributed to automobiles. The pumps can also move fuel from one vehicle to another or take ouRead more
A transfer pump is used to transfer various gases and liquids from one position to another position. This type of pump moves fuel from a container to a nozzle or from one tank to another so that it can be distributed to automobiles. The pumps can also move fuel from one vehicle to another or take out fuel from an automobile and return it to a storage vessel. Diesel transfer pump uses to fuel all types of diesel automobiles, including plant equipment, truck vehicles, cars, coaches, trucks, and buses, etc. Diesel transfer pump presents in the fueling system that allows fuel to move from one location to the desired location. These pumps also use in various industries and adaptable applications.
See lessWhat are the steps for cleaning diffusion pump cooling lines?
Disconnect the lines and add additional temporary plumbing to flush the system with a pump and 2 buckets. Use a solution of CLR and water in one bucket and flush through the lines to the other bucket. Preferably, flush backwards through the system to break things up first, then flush through in theRead more
Disconnect the lines and add additional temporary plumbing to flush the system with a pump and 2 buckets. Use a solution of CLR and water in one bucket and flush through the lines to the other bucket. Preferably, flush backwards through the system to break things up first, then flush through in the normal direction. Flush with plain water before reconnecting the system. If this does not work, repeat the process with a solution of muriatic acid.
See manufacturer recommendation for chemical mixtures and MSDS for safety.
See lessWhen should we perform Temperature Uniformity Surveys (TUS)?
In general, we can say that there are two circumstances: 1) According to the frequency specified by the applicable standard (AMS2750, CQI-9, API) 2) When a modification is made to the equipment. Here it is important to be clear about the word "modification". In general terms, a modification is an alRead more
In general, we can say that there are two circumstances:
1) According to the frequency specified by the applicable standard (AMS2750, CQI-9, API)
2) When a modification is made to the equipment.
Here it is important to be clear about the word “modification”. In general terms, a modification is an alteration or adjustment that could affect the thermal characteristics of the equipment.
Both #AMS2570 and #CQI9 provide very clear guidance on what is a modification and what is not. Some examples of equipment modification:
If you want to learn more about these standards, you can follow the blog of Global Thermal Solutions LLC to find useful articles related to #heattreatment management.
See lessCan a thermocouple be twisted?
Per AMS2750F, thermocouples can be twisted or bead welded as long as no filler material is used. Proper procedures in constructing either hot junctions is imperative.
Per AMS2750F, thermocouples can be twisted or bead welded as long as no filler material is used. Proper procedures in constructing either hot junctions is imperative.
See less