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Vacuum Furnace Systems, controls and Manufacturing
Vacuum Brazing and Vacuum Heat Treating Services
Thermal Spray Coating services, Plasma and High Velocity Oxy-fuel (HVOF) Spray Coatings and Inorganic Paint and Pack Coatings
Vacuum Furnace Technology column by Dan Herring, Metallography column by George Vander Voort, Vacuum Brazing column by Dan Kay, Vacuum Pump column by Howard Tring and other Educational Resources

vacuum-furnace-v350The standard VAV Series Vertical, Bottom-loading, Vacuum Heat Treating and Brazing Furnace can be customized to suit unique applications such as high pressure gas quenching, high temperature heat treating, ultra-clean processing and more.

The furnace is designed to have fast heating rates to very uniform temperatures at high vacuum levels. Standard units are equipped with a gas quench system capable of cooling the load rapidly from processing temperatures at quench pressures up to two bar.

Advanced microprocessor controls are used exclusively to ensure precise control and repeatability. VAC AERO control systems can be integrated with internal networks and offer extensive data collection capabilities. VAC AERO also manufactures auxiliary equipment for quench gas storage and furnace cooling requirements.

Custom or Standard Furnaces Sizes Available


TEMPERATURE UNIFORMITY: Meets or Exceeds AMS 2750 Requirements.


VAC AERO hot zones have unitized construction for easy removal and maintenance. Lightweight design with low thermal mass and inertia for faster quenching and long life.

  • Work Load Size: Standard sizes up to 84” diameter x 84" high. Larger models are also available.
  • Heating Elements: Customer’s choice of lightweight curved graphite, pure or lanthanated molybdenum strip.
  • Hearth: Constructed with quickly removable hearth rails of pure molybdenum designed to support uniformly distributed loads up to 4000 lbs at 2400°F.

    vert_hot_zone-3.gifRadiation Shields: (Graphite-based Construction):

    The standard graphite-based insulation package consists of three layers of carbon felt with a inner facing of graphite foil bonded carbon composite for added protection and enhanced reflectivity. The heat shield package is supported by a stainless steel assembly that also acts as a manifold to distribute the quenching gas uniformly throughout the workload.

    Radiation Shields (All-Metal Construction):

    For ultra-clean processing applications, VAC AERO also offers an all-metal hot zone construction. The standard all-metal insulation package consists of two layers of pure molybdenum sheet backed by three layers of stainless steel sheet. The heat shield package is supported by a stainless steel assembly that also acts as a manifold to distribute the quenching gas uniformly throughout the workload.


    The chamber and heads are a double-wall water-cooled design, primed and painted the customer's choice of colour. The chamber is equipped with all necessary thermocouple jacks, gauge ports, pumping ports and gas quench entries conveniently located for easy access. The tank assembly is vertically aligned with a bottom opening load head. The bottom head and the load are raised and lowered smoothly by a constant speed, ball screw driven lifting jack. Once lowered, the bottom head rolls out from beneath the furnace by means of a powered drive assembly to allow 360° access to the load. The tank is equipped with a powered rotary clamping system to secure the bottom head during processing. A "ground fault" system is used to detect if the load or fixtures touch the heating elements during loading or unloading and will stop the elevator to prevent damage.


    The vacuum pumpdown is automatic and interlocked. The VAC AERO design uses a holding pump to maintain a low pressure on the diffusion pump foreline at all times. This feature, combined with proper timed sequencing of vacuum valves, virtually eliminates backstreaming of pump oils.

    • Mechanical Pump: Roughing Pump and Booster combination appropriately sized for furnace volume.
    • Diffusion Pump: Varian series complete with charge of Dow Corning fluid.
    • Holding Pump: Rotary vane pump.
    • Main, Roughing and Foreline Valves: Right angle poppet valve with electropneumatic operation.
    • Partial Pressure Capabilities: The furnace can be operated at partial pressures up to 1 torr (1000 microns) of inert gas (argon or nitrogen, whichever is used for quenching). Failsafe hydrogen partial pressure systems are also available.


    VAC AERO’s IG Series Quench Gas Storage Systems are available as an option.

    External recirculating inert gas quenching system distributes quench gas through circumferentially located internal nozzles for rapid, uniform cooling of the work load. The system includes:

    • Quench blower powered by electric motor with soft start.
    • Special high efficiency tube/fin heat exchanger.
    • Complete quench piping.
    • Selectable operating pressure.

    vertical_hardwarealarms.gifPROCESS CONTROLS with SCADA:

    The VAC AERO control system is programmable and logic based. The design philosophy of VAC AERO is to simplify control by using the program capabilities to perform as many functions as possible, thereby reducing operator dependence. VAC AERO has also chosen proven hardware components, suitably hardened for an "industrial shop" environment. The system uses a state-of-the-art Hybrid controller to control the machine functions and furnace temperature. The controller integrates with software running on a personal computer to provide Supervisory Control and Data Acquisition (SCADA). Operator interface is provided though an LCD touch-screen mounted in a control panel. An extensive range of standard displays is available.

    The key benefits of this system are:

    • Compatible with plant wide SCADA and network integration.
    • Process cycle validation.
    • Extensive alarm and event management and reporting.
    • Temperature control using advanced algorithms, auto tuning, and multiple PID loops.
    • Operator sign-on/sign-off security provides up to 255 control levels to limit operator control of individual items of plant and equipment.
    • Enhanced maintenance and troubleshooting management and trending.

    Vacuum Instrumentation: A Vacuum Gauge Controller with 2 station, thermocouple gauge and 1 station Penning (cold cathode) gauge is used to monitor the chamber and the pumping system. This instrument is integrated with the process controller to provide dedicated setpoints that control all critical vacuum-related process functions.

    Overtemperature Safety Controller: Digital manual set 0°F - 3100°F, Type S.

    Power Supply: The heating element power is supplied by an A.C. water cooled power supply containing single phase VRT assemblies. Each VRT has a 0 – 100% trim control for optimum temperature uniformity in the hot zone.


    Furnace water system consists of a compact manifold containing all necessary pressure regulators, valves, pressure switches and flow regulators with supply and drain hoses and fittings. As an option, VAC AERO can provide a Dual Loop Cooling System to supply coolant to the furnace.


    The system is shipped complete, tested and ready for installation. VAC AERO offers installation supervision or complete installation services. After installation, a qualified VAC AERO technician will visit the site to commission the equipment and provide instruction in furnace operation. As part of every furnace contract, VAC AERO also provides pre-delivery training in heat treating processes furnace operation and maintenance.

    pdf_fileicon.gifDownload VAV Series Furnace Specs

    pdf_fileicon.gifDownload VAV series Auxiliary System Product Sheet

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    VAC AERO News, Education & Training

    vacuum-furnace-manufacturersVAC AERO Recently Sold Six Vacuum Furnaces to Repeat and First-Time Customers

    Burlington, Ontario, October 12, 2014 –  Burlington, Ontario – VAC AERO’s furnaces continue to be in demand in North America and Asia. Six vacuum furnaces were sold recently to companies active in aerospace, research & development and manufacturing. Three furnaces will be used to process parts for the aerospace industry – a market where VAC AERO and its equipment has a strong reputation and presence. VAC AERO supports its worldwide client base through all stages of the furnace’s life cycle; whether it is installation, expert training and start-up assistance or delivering 24-hour field support and spare parts.

    About VAC AERO's Vacuum Furnace Manufacturing Division

    VAC AERO designs and builds a wide range of vacuum furnaces with the highest quality standards that will fulfill any specialized processing needs. From small horizontal models to large vertical furnaces VAC AERO vacuum furnaces are ideal for a broad range of vacuum processing applications of specialty alloys and engineered materials including vacuum heat treating and brazing (steels, superalloys, titanium), vacuum sintering (steels, titanium, advanced ceramics), hardening, tempering, annealing and a host of other special processes. VAC AERO vacuum furnaces operate worldwide in diverse applications in aerospace and other high-tech industries. For more information CLICK HERE.

    Vacuum Technology with "The Heat Treat Doctor"

    vacuum furnaceVapor Pressure and Evaporation in Vacuum Furnaces

    Knowledge of vapor pressure and rates of evaporation of various materials is valuable information for those operating vacuum furnaces, whether we are heat treating or brazing at high temperature and low vacuum levels or dealing with outgassing at very low temperatures and pressures. When we think about a solid or liquid in a sealed vessel, we find that, even at room temperature and atmospheric pressure, there are molecules that leave the surface and go into the gaseous phase. The gas phase thus formed is called a vapor. The process of forming a vapor is known as evaporation and the rate of evaporation is determined by the temperature of the substance involved. In time, some of the evaporated molecules will, in all likelihood in the course of random movement, strike and stick to the surface of the vessel. This process is known as condensation and the rate of condensation is determined by the concentration of gas molecules (that is, the pressure of the evacuated gas). Eventually, the number of molecules leaving the surface of the substance is equal to the number returning to it (that is, the evaporation rate equals the condensation rate) and we have dynamic equilibrium. The (partial) pressure at which this occurs is known as the vapor pressure of the substance. Below this pressure, surface evaporation occurs faster than condensation, while above it, surface evaporation is slower.

    Vacuum Brazing with Dan Kay

    vacuum furnacesBraze-Fixturing Tubing/piping Using Prick-punching

    A number of people have inquired about how to keep tubing or piping centered in holes or fittings prior to brazing, thinking (erroneously) that if the tubing/piping does not remain centered in the joint, but instead touches one surface or another inside the joint (due to lack of centering) that the joint therefore may be weakened thereby, or that the molten brazing filler metal (BFM) will not be able to penetrate the area where the tubing/piping contacts one of the surfaces inside the joint.  That is incorrect thinking, because molten brazing filler metal (BFM) is able to penetrate extremely tight joints, even when there is metal-to-metal contact in some portions of the joint.  The microscopic surface roughness of the mating surfaces inside the joint will allow the liquid BFM to penetrate completely. But, if you are in that group that feels that you must take steps to keep the tubing or piping centered in the joint to be brazed, and want to take steps to prevent any joint surfaces from touching, then there is a simple way by which to insure that the tubing/piping will remain centered in the joint throughout the braze-cycle.

    Metallography with George Vander Voort

    vacuum-furnacesRevealing Prior-Austenite Grain Boundaries

    Revealing the prior-austenite grain boundaries in heat treated steel is probably the most difficult, and frustrating task, faced by the metallographer or metallurgist. Grain boundaries, regardless of the type, are generally impossible to see in cast metals, as they solidify dendritically and segregation is present and often substantial. After deformation and annealing, if recrystallization occurs, grain boundaries in the product may be visible, but they are not necessarily prior-austenite grain boundaries. In a deformed, partially recrystallized specimen, it is usually possible to see both recrystallized and non-recrystallized grain boundaries. But, prior-austenite grain boundaries are those of the steel when it was austenitized prior to quenching and tempering. If the steel’s microstructure is fully martensitic after hardening, or contains some retained austenite or lower bainite, the prior-austenite grain boundaries may be revealed. They can often be revealed in specimens isothermally processed to obtain fully lower bainitic microstructures; but they cannot be revealed if the transformation microstructure consists of upper bainite, pearlite and/or ferrite. Composition also is important in trying to reveal the prior-austenite grain boundaries, as is the tempering temperature. In general, steels with low carbon contents and low phosphorous contents are very difficult subjects.  This article summarizes the state-of-the-art in revealing prior-austenite grain boundaries.

    Vacuum Pump Practice with Howard Tring

    vacuum-furnaceFive Main Reasons for using Vacuum - Part 5

    This article completes the series of Five Main Reasons that vacuum is used in science and industry; To provide a working force, to remove active and reactive constituents, to remove trapped and dissolved gases, to decrease thermal transfer and finally to increase the mean free path to a useful dimension. The article printed back in January this year talked about solid, liquid and gas states of matter. The following is a short excerpt from that article. “In a gas the atoms and molecules are generally much further apart than in solids and liquids. In air at atmospheric pressure and room temperature the actual space occupied by atoms and molecules is about 0.01 per cent or one ten thousandth of the volume. The equivalent for solid copper is about 74 percent or close to three quarters. (So much for being called a “solid”). In air the molecules are in constant random movement, typically in a straight line, and the interatomic forces have little effect due to the space between the molecules. The moving molecules will constantly collide with other molecules and then move away in a different direction. These collisions occur about 10,000,000,000 times per second at atmospheric pressure”.

    Front and Bottom Loading Vacuum Furnaces

    vacuum heat treating furnacesVAC 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 and/or long parts.

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