| 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. |
December 2009 |
905-827-4171 |
| VAC AERO Completes Plant Re-organization | |
VAC AERO's Oakville Thermal Processing Division recently completed an extensive plant re-organization based on lean and green manufacturing concepts.
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The project included building renovations to create more production space, the addition of new work-handling and production capacity, safety enhancements and energy efficiency improvements in lighting and power consumption. Lean manufacturing techniques that were implemented in the re-organization included Kanban systems, 5S and visual signals. The company has also been working in close partnership with customers on value stream mapping and smoothing production flow. The effort is already paying benefits. For example, distances travelled for orders within the shop have been reduced on average by 50%. On-time deliveries have improved dramatically, now in many cases being maintained at 100%. VAC AERO invested more than $400,000 in the re-organization, a portion of which was subsidized by a provincial government grant. |
The completion of the re-organization was timed to coincide with the commissioning of VAC AERO's fourth large vacuum oil quench furnace, designed and built by the company's Furnace Manufacturing Division. The new furnace will add significant capacity to the Oakville vacuum oil-quench operation, already one of the largest in the world.
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| Vacuum Pumping Systems Part 2 | by Dan Herring | This is the fourth in a series of articles in our Vacuum Heat-Treatment Series. Here we conclude our discussion of vacuum pumping systems by reviewing the operation of diffusion pumps as well as offering troubleshooting tips for all types of vacuum pumping systems.
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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 reach extremely low vacuum levels, the use of diffusion pumps is required.
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Diffusion Pumps: The diffusion pump (Fig. 2) consists of a boilerplate system in which a high-grade silicon fluid is heated and then subsequently vaporized during boiling. This is typically accomplished by means of an external heating element and a stack assembly, or chimney (commonly referred to in the industry as a "Christmas tree assembly"), through which the vapors pass. Read more >> |
NEXT TIME - Part five of this series begins a discussion of the types and characteristics of vacuum gauges and offers insights into which gauge should be used when working in a specific vacuum range.
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| Braze Joint Design Considerations - Part 2 | by Dan Kay | For successful brazing to occur, the joints to be brazed have to be designed properly, and then properly manufactured to attain and maintain those shapes and dimensions. This second article looks at joint clearance considerations in more detail. Next month we'll talk about the effects of dissimilar metal brazing on joint design.
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For successful brazing to occur, the joints to be brazed have to be designed properly, and then properly manufactured to attain and maintain those shapes and dimensions. This brief article looks at the first of some important design considerations to insure that brazed joints will work. Next month we'll look at joint clearance considerations in more detail. |
Joint clearances must be close together and parallel - The amount of clearance between the faying surfaces (the mating surfaces inside a joint being brazed) should ideally be kept small, on the order of about 0.000"-- 0.002" (0.000-0.050 mm) total, so that capillary action can most effectively pull the molten brazing filler metal (BFM) completely into and throughout a braze-joint. Read more >> |
NEXT TIME - In next month's article we'll address some additional factors in joint design, specifically the topic of "differential metal expansion". All metals expand at different rates when heated, and since braze-joint clearances are calculated based on expected clearances at brazing temperature, we need to know how to properly optimize brazing of different metals in the same assembly.
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| Martensite and Retained Austenite | ||
| by George F. Vander Voort | ||
Martensite development is critical to many heat-treatment processes. This paper examines the conditions under which austenite is retained and the problems associated with its presence, with detecting it and with measuring it.
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Depending upon the carbon content of the parent austenite phase, either lath (low-carbon) or plate (high-carbon) martensite may form, as well as mixtures of the two. In general, lath martensite is associated with high toughness and ductility but low strength, while plate martensite structures are much higher strength but may be rather brittle and non-ductile. |
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