VAC Burlington, Ontario, February 16, 2015 - VAC AERO has recently received orders for three complete all-metal hot zone refurbishments for customers in Florida, Connecticut and Indiana, in the Aerospace, Medical and Commercial Heat Treatment industry sectors. The retrofit work is for two horizontal and one vertical furnace. VAC AERO hot zones feature unitized construction for easy removal and maintenance. The lightweight design’s low thermal mass enables faster quenching and longer life. The heat shield package consists of one layer of .020” thick lanthanted molybdenum (Mola) sheet backed by one layer of .010” thick molybdenum sheet, and three layers of .014” stainless steel sheet.
We continue our discussion on the factors that must go into the decision making process during the acquisition phase of a vacuum furnace. Part One focused on how one goes about choosing the right furnace for the job and talked about the various choices for hot zones (e.g. insulation, heating elements, etc.). Part Two discussed pumping systems, controls and ancillary support items (e.g., grids/baskets/fixtures, water systems, features & options). It is now time to understand how your supplier partner will handle the project once an order is received, including project management, codes & standards, approvals, installation, commissioning and long-term support.
Over the years the brazing and welding industries have noticed something strange that sometimes happens when joining 304-stainless steel assemblies for a wide variety of applications exposed to outdoor weather. They noticed that sometime after the weldment or brazement was placed in service in situations where the stainless-assembly was exposed to moisture (such as in outdoor applications for automotive, aerospace, and tooling applications, etc.), the stainless steel started rusting, as if it were made from a regular carbon-steel rather than stainless-steel.
The interlamellar spacing of pearlite is a very important microstructural parameter for steels containing pearlite, and becomes more important as the pearlite content increases towards a fully pearlitic microstructure. As the amount of pearlite in ferrite-pearlite microstructures increase, so does the strength, but toughness and ductility decrease. For a fully pearlitic steel, as the interlamellar spacing becomes finer, strength, toughness and ductility all increase. Consequently, in structure-property correlations it is important to measure the interlamellar spacing. This paper reviews procedures for performing such measurements. Due to the fineness of the spacing, either SEM images or TEM images of replicas or thin foils can be utilized. The range of spacings in a given specimen will be much narrower if the pearlite in the steel was formed isothermally rather than transformed over a range of temperatures, as in as-rolled or normalized steels.
The correct use of the Gas Ballast valve on a mechanical oil sealed rotary vacuum pump has always been seen as “black science” or just plain guesswork. It is a very simple device and when used correctly can keep a vacuum pump working well even though it may be used on a very wet process and the oil becomes contaminated with condensed vapors. One series of vacuum pumps I worked with had a gas ballast valve that had no stop when opened. If you unscrewed it enough the ballast knob would come off in your hand allowing maximum air to enter the pump, the pump to become noisier and a blast of oil mist to come out of the exhaust. I always thought that if a lab technician ever did that they would replace the knob and never ever touch the gas ballast valve again.
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.