When vacuum furnaces were first introduced, many in the industry felt that the only acceptable part and fixture cleaning method was solvent vapor decreasing. Over the years, however, environmental and other factors have necessitated the use of aqueous systems.
A common problem experienced by almost every vacuum user is that, over time, leaks develop that are both damaging to product quality and to furnace internal components. In extreme cases, the problem is obvious: the furnace will not pump down and/or the hot zone (or heating elements) shows obvious signs of oxidation.
Valves intended for vacuum service are subjected to a variety of special conditions ranging from high and ultrahigh vacuum levels to low, high and ultrahigh pressures, differentials in pressure and differentials in temperature as well as variable frequencies of mechanical operation.
The reality around the globe is that nuclear energy is here to stay not necessarily because we’re convinced it is the best option, that it does not carry with it short- and (very) long-term consequences or it is easy, but because it is the most sustainable energy source capable of meeting near-term energy demands.
One of our goals in vacuum furnace processing is to minimize both alloy depletion from the part surface and subsequent hot zone contamination. Many of the materials we run are processed at temperatures and pressures at which individual elements can volatilize (leave the part surface).
This article talks about heating elements used in vacuum furnaces, the materials and temperatures of operation, forms and maintenance practices. The design and location of the heating elements is critical to achieve proper heating and uniformity of temperature.
This article talks about vacuum hot zones, their history, construction and maintenance. The type of hot zone construction is often important both to the material and to the process.
All solids and liquids have a tendency to evaporate into gaseous form, and all gases have a tendency to condense back into their liquid or solid form. In other words, all materials have a characteristic vapor pressure that varies with temperature.
This is a comprehensive look at every feature article that appeared in the pages of Industrial Heating throughout 2009. The articles are broken down by month and by subject matter.
This is the sixth in a series of articles in our Vacuum Heat-Treatment Series. Here we continue our discussion of the types and characteristics of vacuum gauges.
Counting molecules is a job for vacuum gauges. Depending on the type of vacuum systems and the required operating vacuum level, different vacuum gauges are required – often in combination with one another – to accurately determine and/or control the vacuum level of the chamber at any given moment in time.
Vacuum pumps are the heart of a vacuum system. While mechanical pumps have the ability to work against atmospheric back pressure and booster pumps improve the speed and level to which we pump down, these pumps have the disadvantage of losing efficiency as the system pressure continues to lower.
In order to create a vacuum within a closed container, or vessel, we need to remove the molecules of air and other gases that reside inside by means of a pump. The vacuum vessel and pumps (mechanical, booster, diffusion, holding) together with the associated piping manifolds, valves (mechanical pump, high vacuum isolation, vacuum (brake) release, backing), vacuum measurement equipment (molecule counters) and traps comprise a typical vacuum system.
In vacuum heat, we are always dealing with the movement of gases. So, everyone needs to understand something about the nature (theory) of gases and how they behave, especially in vacuum.
A vacuum system (Fig. 1) provides a space in which the pressure can be maintained below atmospheric pressure at all times. The primary advantage of vacuum heat treatment is its versatility.
Process control quality for heat treatment, be it surface treatment or other metallurgical process, depends on quality procedures to accomplish process reproducibility.
If you thought you were done with school once you graduated from college, there’s a good chance you were wrong. Education and training do not end when your career begins. In fact, the opportunities for continuing education and training are endless. They are also vital in today’s business environment.
The following is a comprehensive bibliography of all feature articles that appeared in Industrial Heating in 2008. You can search for an article by month and/or subject matter.
