- Written by Administrator
- Created: 30 July 2007
Burlington, Ontario, February 18, 2014 -VAC AERO has recently commissioned a horizontal vacuum furnace at a major South Korean university metallurgical research center. The VAH5058 HV-8 furnace chamber is 36” wide X 36” high X 58” long with a hot zone comprised of high efficiency graphite felt, carbon composite and curved graphite elements. It is equipped with a gas quench system capable of quickly cooling the workload from processing temperatures, at quench pressures of up to eight bar. 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.
Component parts come in all shapes and sizes. To meet this demand vacuum furnaces have been designed to accommodate many standard workload configurations. Despite the almost limitless choices, some common sense rules apply. It is important to recognize that loading arrangements generally fall into two classes: weight limited and volume limited. In either case, when loading parts in furnace baskets or onto racks the goal is often to maximize loading efficiency. One must also be concerned with proper part spacing, that is, how parts are situated within the load for optimal heat transfer (e.g. line of sight heating), support and stability of the load at temperature, temperature uniformity, and heat extraction during quenching so as to achieve the desired metallurgical properties and minimize distortion.
Vacuum brazing is a growing industry, with more and more companies entering it each year, due primarily to the bright, clean, as-brazed component surfaces resulting from brazing in a vacuum environment, which, when conducted properly, allows brazed components to be used immediately, with no additional cleaning operations needed after brazing. Of course, that assumes that the vacuum furnace is clean and tight, with a minimal leak-up rate. Leak-up rate? What? Do vacuum furnaces leak? Yes, every vacuum furnace, unfortunately, is leaky! There are many fittings, connections, seals, etc., on each vacuum furnace, and it is very important that all such seals and connections be as leak-tight as possible. Otherwise, air will leak into the furnace through any of those potential leak-paths and the pressure inside the furnace will start to go back up toward atmospheric.
March 9, 1862 marks the date when the USS Monitor and the CSS Virginia (formerly the USS Merrimack) fought an indecisive naval battle at Hampton Roads that changed naval warfare from wood and sails to iron and steam. The USS Monitor sunk off the Outer Banks of North Carolina during a storm on December 31, 1862 but its remains were discovered in 1973. The wreck site, the Monitor National Marine Sanctuary, is managed by the National Oceanic and Atmospheric Administration (NOAA). The Confederates began construction of an “ironclad” ship at the Gosport Yard of Hampton Roads in 1861. This was well known to the Union Navy Department. The US Army had actually launched ironclad gunboats in the summer of 1861 to patrol the Mississippi River; but none were available in the east to counter the Virginia.
For many vacuum applications the process is a cyclic one. The workload is placed in the chamber, the chamber is evacuated and the process takes place. The chamber is then let back up to atmospheric pressure and the process workload is removed. These cycles can be as short as a few seconds in the case of coating a small communications crystal (Fig.1) to give it a specific frequency, or it can take several hours in the case of a heat treating cycle that may include evacuation, heating, soaking, cooling and eventually back to atmospheric pressure. In this type of cycle the main “constituent” being removed is “air”. However, "air" is a bit more complicated than it seems. Let’s look at what main gases are present in dry air. There are two or three rare gases not included and the total will not add up to exactly 100%.
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.
With the economic recovery, rare-earth and key industrial metal prices have jumped as worldwide demand increased and as Chinese export quotas crimped worldwide supplies for the materials used by the thermal spray industry. Tungsten carbide, Yttria, Nickel and Molybdenum are the most recent examples of severe raw materials price increases. With global economic factors and competition, the thermal spray industry encounters strategic challenges of productivity and competition. Thermal spray coatings are becoming more and more complex with frequent feature enhancements, more severe operating conditions as well as coating life improvement - while raw materials prices are increasing. Being largely based on coating price the thermal spray competition must continue to create and bring new and highly differentiated products to the market cost effectively and within compressed time frames.
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.