| The Monthly Newsletter of Vac Aero International Inc. | If you are having trouble viewing this e-mail, click here. To log on to the VAC AERO web site, please click here. |
September 2009 |
905-827-4171 |
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Come visit us, booth 2004 Heat Treat 09 |
| VAC AERO Launches Redesigned Website for its 50th Anniversary | |
| For immediate release | |
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Oakville, Ontario, September 9, 2009 – VAC AERO International launched its newly redesigned website and a new French version today as part of its 50th anniversary online and print campaign. In addition to featuring concise overviews on its vacuum furnace systems and metallurgical services, VAC AERO offers a host of technical articles relating to the practice and application of thermal processing and surface engineering in its Resources section. |
“Vacuum heat treating is highly specialized and we understand how crucial research is in our industry,” says Alan Charky, VAC AERO’s director of marketing. “That’s why we’re constantly updating our website with heat treating and brazing articles that help our customers and their employees keep pace with the development of new processes and technologies,” continues Alan. Read more >> |
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| All About Vacuum | |
| by Dan Herring | |
This is the first of a series of articles in our Vacuum Heat Treatment Series and is designed to explore the nature of vacuum, how it is used throughout the thermal processing industry and review the processes and applications that benefit most from its use.
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Design features, operational issues and maintenance practices will be covered, all of which are necessary to produce quality component parts in captive and commercial heat treat shops servicing the Aerospace, Automotive, and Industrial markets.
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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 a vacuum heat treatment is its versatility. In almost all cases it provides a “safe” environment with respect to the surface of the components being treated, is self-contained, and uses cycles/recipes that can be reproduced consistently. When not in use, like an electric light, it is simply turned off. When turned back on, minimal conditioning time is required. |
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NEXT TIME - Part two of this series will teach us all about how gases behave in a vacuum environment, look at the equations needed to explain their behavior and explore what happens when we pump down a vacuum vessel. Read more >> |
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| Are the use of dead-weights for fixturing a recommended practice? | |
| by Dan Kay | |
The effective use of "metallurgical fixturing", instead of a lot of dead-weights, to effectively "load" parts with enough pressure to keep braze joints close together for effective brazing is described in detail. |
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The use of heavy weights on top of parts being brazed is a common practice. Its purpose is to load the top of the assembly with enough weight so as to insure that the components of the assembly will be pressed together sufficiently to keep the joints from opening up during furnace brazing. This should then insure that good capillary action of the brazing filler metal (BFM) into those joints will occur during the furnace cycle. Unfortunately this procedure does not always work (which can be very frustrating for te furnace operators).
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Look at the two drawings in Fig. 1a and 1b, which shows two ways by which some heat-exchanger components might be fixtured for brazing. The assembly-layers on the left are being held together by placing a lot of dead-weights on top of a heavy flat plate located on top of the heat-exchanger corrugated assembly. It is very important to know how much weight per square inch (or per square centimeter) is applied to this load, and if that amount of loading would be sufficient to "yield" the base metals enough to keep the joint surfaces close together for good capillary action to occur. |
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One brazing shop had placed hundreds of pounds of dead weight on top of a flat, large-surface-area heat-exchanger assembly, only to find that the pressure that resulted from that loading only amounted to about 2-lbs per square inch, and wasn't enough to insure flatness of the assembly during brazing. Read more >> |
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