Burlington, Ontario, July 20, 2015 - VAC AERO has sold a VAV6648 HV-2 vertical vacuum furnace to an international airline company. The furnace is designed to have rapid heating rates while maintaining tight uniformity at high vacuum levels. The furnace features a 66” diameter x 48” high hot zone using metal elements in a graphite hot zone and a heavy duty hearth designed to support a uniformly distributed load of 4400 lbs. The furnace, which is capable of meeting applicable AMS 2750E requirements, is also equipped with VAC AERO’s advanced Honeywell HC900 interactive hybrid control package with SCADA and complete network integration capabilities and remote monitoring and control. VAC AERO’s 50-plus years of experience operating its own heat treating facilities allows them to provide turnkey solutions to customers such as technology transfers as well as training, hands-on instruction and collaboration.
Tungsten is used in vacuum furnaces when there is a need for structural integrity at elevated temperature and/or in situations where other materials may degrade, such as when lower melting point eutectics are a concern. One example of its use in is roller rail assemblies in which graphite wheels are positioned between molybdenum rails using tungsten axles. Tungsten (chemical symbol W) is a member of the family of refractory metal (Mo, Nb, Re, Ta, W) and has the highest melting point and vapor pressure of this group. Due to this unique property, it is commonly used as a material of construction in specific areas of vacuum furnace hot zones operating above 1315ºC (2400ºF). Tungsten can also be used for heating elements given that it has the highest duty temperature, typically 2800°C (5075°F). In practice, this rating is often downgraded as it is for all heating element material choices. Tungsten will become brittle, however, if exposed to oxygen or water vapor and is sensitive to changes in emissivity. In general, tungsten is resistant to corrosion below 60% relative humidity.
All metals expand when they are heated, and contract when they cooled. This fact has been thoroughly explored over the years, and data-tables have been published showing the coefficients of thermal expansion (CTE’s) for each of the many metals available for use in product design and construction. But carbon-steels present a unique situation to designers and brazing companies, because when being heated all the way up to copper-brazing temperature, the metals will actually go through a temperature-range where the steel will actually be contracting (shrinking) while being heated, and then do just the opposite when cooling, thus potentially causing distortion and/or fracturing of brazements during a high-temp brazing cycle. Such a scenario is illustrated in Fig. 1 where an automotive fuel rail brazement failed to braze properly, because some unique CTE problems associated with carbon-steels was not properly taken into account during the furnace brazing cycle.
Measurement of the amount of phases or constituents in metals and alloys is probably the most commonly performed quantitative microstructural test. The amount present is usually referred to as the volume fraction, although it is rarely expressed as a fraction but usually as a percentage. The volume fraction, or VV, in stereological terms, is the volume per unit volume of the phase or constituent. However, there is no simple direct way to measure the volume fraction. Instead we measure the area fraction, AA, a lineal fraction, LL, or a point fraction, PP, which can be measured and correlate with the volume fraction: VV = AA = LL = PP. Areal analysis was first described by Delesse, a French geologist, in 1848. As the minerals were rather coarse in size, he could measure the area fraction of the grains of interest compared to the total two-dimensional area. As microstructures are rather fine in size, this is not a simple method to perform manually. Delesse suggested that a linear ratio of dimensions could also be used, but he thought that the accuracy would not be as good and did not try to develop a lineal analysis method.
On any machine that has a rotating shaft there will be a shaft seal of one type or another. If the machine is a simple electric motor, for example, the seal may be used just to retain the lubricant in the bearings and to prevent dust and dirt from entering the bearing. This type of seal generally needs little or no maintenance for small motors from ¼ to perhaps 10 HP. The shaft seals in any pump that the electric motor drives are ones that do need maintenance and replacement, whatever type of pump it is. If the pump moves liquids, such as a centrifugal water pump, it is important that the seal doesn’t leak although in some applications a small amount of leakage can be tolerated. If the liquid being pumped is hydraulic fluid, it may be at high pressure and the seal would be designed to withstand that pressure without failing.
Constructed of the finest materials and craftsmanship, VAC AERO’s high performance vacuum furnaces are operator friendly and designed to minimize maintenance and downtime to deliver outstanding quality and value to commercial and in-house heat treaters alike. VAC AERO’s vacuum furnaces are designed for rapid heating rates to very uniform temperatures at high vacuum levels and can be customized to suit unique applications such as high pressure gas quenching, high temperature heat treating, ultra-clean processing and more. VAC AERO’s high efficiency hot zones are designed for easy maintenance and reduced energy consumption. Our external quench system allows for easy maintenance of the heat exchanger and quench motor. A high efficiency blower and motor combine fast cycle times and quenching speeds to provide uniform gas distribution and superior cooling performance from processing temperatures at pressures of up to 10 bar.