- Written by Administrator
- Created: 30 July 2007
Burlington, April 14, 2014 - The production-scale, 2-bar VAH3436 horizontal vacuum furnace with work zone dimensions of 24” wide x 24” high x 36” is designed to process aerospace parts under high-vacuum and partial pressures with excellent process control and is rated at a normal operating temperature of 2400°F (1316°C). The hot zone is comprised of curved graphite elements and the heavy duty hearth is constructed with quickly removable rails of pure molybdenum designed to support a uniformly distributed load of 1000 lbs at 2400°F. The vacuum chamber and door are constructed of carbon steel and feature a double-wall, water-cooled design. The furnace operating system is based on VAC AERO's versatile HC900 interactive hybrid control package with SCADA and complete network integration capabilities and remote monitoring and control. The furnace is expected to run at full capacity next month.
A residual gas analyzer or RGA for short is a compact mass spectrometer, designed for use either in the laboratory or out on the shop floor. These devices are often mounted for in-situ use on a vacuum furnace. RGA’s are typically designed for process control and contamination monitoring in vacuum systems. Applications for residual gas analyzers include distinguishing leaks from outgassing, fingerprinting the process background, detecting helium and determining the effectiveness of gas line purging. A typical RGA gas analysis can reveal how much of a particular species is present either in the vacuum vessel or in the pump manifold. RGAs are used in most cases to monitor the quality of the vacuum and easily detect minute traces of impurities in the low-pressure gas environment. These impurities can be measured down to 10-14 Torr levels, possessing sub-ppm detectability in the absence of background interferences.
On a warm, moist day, our earth’s atmosphere will contain a significant amount of moisture in it. During the night, when the sun has gone down, this atmosphere will become cooled, and will not be able to hold onto the amount of moisture (water) that it could when it was warm, and so, some of that moisture will condense out onto the grass in the form of “dew”. Then, during the following day, when the sun heats the air up once again, the dew will evaporate from the ground. It is well known that the warmer the gas, the greater will be the amount of moisture that gas can hold. At any given point in time, all gases will have what is called a “dewpoint”. The “dewpoint” of any gas is the temperature to which that gas must be cooled to get the first droplet of moisture to condense out of that gas (assumed to be at one standard atmosphere of pressure). The “dewpoint” of any gas is the temperature to which that gas must be cooled to get the first droplet of moisture to condense out of that gas (assumed to be at one standard atmosphere of pressure).
There was a crack in the helmet which is not visible in this image (some associated damage can just be seen in the lower left side of the helmet visor). The crack was opened and the fracture began at a streak with mostly intergranular fracture and then propagated by cleavage as shown below. Note the intergranular fracture in the center foreground of the image on the left. The walls show transgranular cleavage that propagated from the intergranular origin. Next to the fracture, we see a region of columnar grains at the surface with a small region of finer, more equiaxed grains below and the very coarse columnar grains below that, as shown on the image on the right. The fracture is along the left edge of the micrograph. Note that there appears to be some mechanical twinning in the grains at the fracture edge. The specimen was color etched with Klemm’s I and the hardness was 124.6 HV (~69 HRB).
As stated last month, in Part 1, this article talks only about one and two stage “medium vacuum” oil sealed rotary vane vacuum pumps that can produce a catalog ultimate vacuum of about 1 x 10-2 Torr (0.01 Torr or 10 microns) for a one stage model and about 1 x 10-3 Torr (0.001 Torr or 1 micron) for a two stage model. Smaller vacuum pumps such as those used in the heating, ventilating and air conditioning industry (HVAC) are not included as they are often only for intermittent use and do not have the design features built into the laboratory sized continuous running vacuum pumps used in industry and science. Larger rotary vane vacuum pumps, ones that require ball or roller bearings to support the weight of the rotor are not included either.
The effect of cryogenic treatment (CT) on the properties of ledeburitic tool steels was investigated. CT is also used in conventional heat treatment to improve mechanical properties and wear resistance and decrease the amount of retained austenite. The technology of CT was developed in the 1960s and still elicits contrary scientific opinions today. Some studies report that CT improves hardness, wear resistance, bending strength, toughness, fatigue strength, etc., but some scientists do not agree. Also, experts do not agree as to the main factor influencing results when CT is applied – austenitizing temperature, cooling rate, quench temperature, holding time, heating rate or tempering temperature.
Using vortex-stabilized units, as described above, coldspray, warm-spray, and hot-spray, each producing impact-fusion, are possible. It is not the same though. Outside water cooling is necessary with nozzle lengths up to 16 in. long using ½ in. bores. The principle is simple. The first couple of inches after the reactants have been introduced into the bore, may be un-cooled. When the flame within the bore is fully stabilized, a small flow of quench water is introduced. Allowing time for a sufficient amount of evaporation of this water to begin limiting the jet stream temperature within the bore — about 6 inches —, then add the powder. Adjust the quench water flow so that the powder being accelerated never melts. It has more than 8 in., or so, to travel to the exit.
VAC AERO offers a wide range of vacuum heat treating and brazing furnaces, from small laboratory models to large vertical furnaces, as well as equipment for CUSTOM applications. VAC AERO offers complete turnkey services, including planning, designing, building and installation of vacuum furnace systems and controls. VAC AERO’s experience, proven through decades of service in commercial heat treating, has provided us with valuable insight into the changing needs and rigorous demands of our furnace customers. As a result, VAC AERO has developed a keen understanding of the design and performance of vacuum furnace systems built to meet the most stringent requirements for reliability. VAC AERO’s vacuum furnace design innovations are thoroughly tested in our own heat treating facilities before being offered to our customers. That means better quality, reliability and efficiency to maximize uptime and productivity. Horizontal vacuum models provide great flexibility for general heat treating and brazing applications and Vertical bottom-loading models are ideal for processing large circular parts such as rings, stators or engine casings and long parts like shafts or rolls.