VAC AERO uses the Honeywell HC900 Hybrid controller to regulate machine functions and thermal cycles. The HC900 is integrated with Honeywell Experion Vista software to provide Supervisory Control and Data Acquisition (SCADA) using a large color touch screen LCD for operator interface. VAC AERO’s programmable, logic based control system is comprised of proven hardware components, suitably hardened for an "industrial shop" environment and optimized to cover all normal operating and alarm conditions. Process information is accessible by operators and across a company’s network for process engineers, allowing control and monitoring for higher productivity, reduced costs and increased quality.
Fastener applications are demanding. Whether fasteners are being used in the petrochemical industry, in medical or mining applications, for assembly of marine or nuclear components or in the aerospace, automotive or construction world, vacuum processing allows us to repeatedly achieve the highest quality and metallurgy. Most fastener materials, including stainless steels and superalloy grades, benefit from or actually require vacuum processing for heat treatment instead of being run under protective atmospheres. In general, there are three main sets of applications that where vacuum heat treatment is used; processes that can be done in no other way than in vacuum; processes that can be done better in vacuum from a metallurgical standpoint; processes that can be done better in vacuum from an economic standpoint.
Radiography (X-ray) is a means of looking at the inside of a braze joint without actually having to cut it apart to see it, as long as the appropriate conditions are met to allow its use. Radiography is heavily dependent on the thickness and mass of the part being radiographed. In order for x-ray to yield a useful image of any voids or inclusions in a brazed joint, the thickness of that void or inclusion should be at least 2% of the thickness of the metal through which those x-rays are being sent, in order for it to be visible in a radiograph, or, if using real-time radioscopy (RTR) on a TV screen or monitor. The “2% Rule” in brazing is a very important guideline to follow, since it can effectively rule out radiography as a method for inspecting components that are too thick to be able to see any of the imperfections inside a braze joint.
One of the most serious limitations to Vickers hardness testing in the micro-load range (10-1000 gf or 0.098-9.81 N) has been the variability in measured hardness with loads ≤ 100 gf (≤ 0.98 N). In the literature four HV-load trends have been reported for this range. In the order of most common to least common, the trends are: the hardness decreases with decreasing load; the hardness increases slightly and then decreases; the hardness increases with decreasing load; and, the hardness is constant. Many publications have concentrated on the most common trend and attributed it to material factors. Samuels  stated, however, that these problems were due to microscope limitations, such as limited contrast and resolution, and visual perception limitations. At the same symposium, Westrich  showed that the SEM could be used to measure small Vickers indents and yield virtually constant hardness as a function of load.
This month I’m going to take a step away from vacuum pumps and systems and write about general applications that use vacuum in the process. There may be some applications you have heard about and some, hopefully, that may be new to you. Whenever a vacuum (a pressure lower than the surrounding atmospheric pressure) is used in a process it will generally fall into one of the Five Main Reasons for using Vacuum. In some cases a process may use vacuum for two of the five reasons. This month I will discuss the first of these reasons, in no specific order.
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.
The United States National Institute for Occupational Safety and Health (NIOSH) recently recommended that the Occupational Safety and Health Administration (OSHA) lower hexavalent chromium exposure levels below previously OSHA-endorsed levels. This recommendation has renewed the discussion on acceptable emission levels in the thermal spray and welding communities. As a result, companies are advised to review their manufacturing processes and equipment and consider implementing proactive changes to control their possible emissions.
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.