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 | Vacuum Applications (Part Four: More Standard & Custom Processes)
In this chapter, we focus on
examples of certain standard and special processes run every day in vacuum
equipment. The types of materials, products and processes vary depending on
the needs of the industry being serviced, but all take advantage of vacuum’s
unique ability with respect to quality and repeatability of cycles and results.
by Daniel H. Herring
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The Basics of Pulse Firing (Part 2)
The basics of pulse firing were
discussed in October’s article. This online-exclusive part summarizes some of
the advantages and disadvantages of pulse as compared to traditional
amplitude-modulating systems.
by Dan Curry
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Interview with Unifrax's David Brooks
Industrial Heating
recently interviewed David Brooks, president and CEO of Unifrax I LLC. The
Niagara Falls, N.Y.-based company, a leading global supplier of
high-temperature insulation products, has acquired five companies in two
separate business deals since late July.
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 | Vacuum Applications (Part Two: Brazing)
Vacuum brazing represents one of the largest application uses for vacuum
furnaces. The transportation industry (automotive and aerospace) in particular
has provided the impetus for increasing demand for vacuum brazing.
by Daniel H. Herring
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 | Vacuum Applications (Part One: Hardening)
Hardening is the most common practice performed on steel components throughout the heat-treating industry. The formal definition of hardening is a process producing an increase in the strength of a material by a suitable thermal treatment usually involving heating followed by cooling at a rapid rate.
by Daniel H. Herring
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 | Baskets, Fixtures and Grids for Vacuum Service
Our mission is to provide an overview of some of the basic requirements necessary for selection of material systems for use in thermal processing applications running from subzero temperatures as low as -320ºF to elevated temperatures as high as 3000ºF and beyond.
by Daniel H. Herring
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Principles of Gas Nitriding
Nitrogen is a case-hardening process in which nitrogen is introduced into the surface of a ferrous alloy such as steel by holding the metal at a temperature below that at which the crystal structure begins to transform to austenite on heating as defined by the Iron-Carbon Phase Diagram.
by Daniel H. Herring
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 | Oil Quenching Technology
Many components use oil quenching to achieve consistent and repeatable mechanical and metallurgical properties and predictable distortion patterns. The reason oil quenching is so popular is due to its excellent performance results and stability over a broad range of operating conditions.
by Daniel H. Herring
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Gas Quenching
Gas quenching from sub-atmospheric to ultrahigh pressures is a technique used to achieve both proper part hardness (surface and core) and optimize part microstructure. Understanding this technology and the factors that influence quenching performance is critical.
by Daniel H. Herring
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Maintenance Practices, Procedures and Tips
To ensure reliability and repeatability of operation as well as uncompromising safety, maintenance practices need to be well defined, understood by all, and implemented in a prudent and well-thought-out manner.
by Daniel H. Herring
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Vacuum Process Instrumentation and Controls
Instrumentation and process controls used on vacuum furnaces in the heat-treatment industry are extremely diverse due in large part to the fact that the life of a vacuum furnace can range from 20 to 50 years.
by Daniel H. Herring
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 | Water Cooling Systems
All vacuum furnaces require some form of cooling either by water or by a suitable fluid with high heat-transfer characteristics. Cooling systems can be designed as either open systems (discharging to a sewer) or closed (recirculation) types.
by Daniel H. Herring
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 | Heat Exchanger Design and Maintenance
Most heat exchangers used in vacuum furnaces are essentially fin cooling units, which depend on the surface area of their coolers as well as the temperature of the incoming water supply to achieve a given cooling rate.
by Daniel H. Herring
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Diffusion Bonding, Eutectic Melting, Outgassing and Related Topics
Diffusion bonding is a solid-state joining process capable of bonding together a wide range of small and large metal and ceramic part combinations. In those instances, however, where our intent was not to join components together, diffusion bonding can be an unexpected problem.
by Daniel H. Herring
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 | Cleaning of Parts and Fixtures
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.
by Daniel H. Herring
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Leak Rates, Leak Detection and Leak Repair
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.
by Daniel H. Herring
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 | Vacuum Valves, Penetrations, Feedthrus and Flanges
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.
by Daniel H. Herring
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The Nuclear Renaissance: Opportunities for the Heat-Treating Industry
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.
by Daniel H. Herring
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 | Partial Pressure, Mean Free Path and Related Topics
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).
by Daniel H. Herring
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 | Heating Elements
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.
by Daniel H. Herring
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 | Hot Zone Construction
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.
by Daniel H. Herring
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Vapor Pressure
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.
by Daniel H. Herring
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2009 Feature Article Bibliography
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.
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 | Vacuum Measurement Systems (Part 2)
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.
by Daniel H. Herring
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Vacuum Measurement Systems (Part One)
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.
by Daniel H. Herring
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 | Vacuum Pumping Systems
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.
by Daniel H. Herring
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Vacuum Pumping Systems
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.
by Daniel H. Herring
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The Theory of Gases
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.
by Daniel H. Herring
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 | All About 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.
by Daniel H. Herring
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Reproducibility and Process Control
Process control quality for heat treatment, be it surface treatment or other metallurgical process, depends on quality procedures to accomplish process reproducibility.
by David Pye
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Education and Training: Opportunities Abound in Heat-Treating Industry
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.
by Bill Mayer
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 | 2008 Feature Article Bibliography
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.
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