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.
Finding leaks in vacuum furnaces is a task that few of us cherish but all of us know is important and necessary. Leaks are a problem experienced by almost every vacuum user. Leaks can occur suddenly or develop slowly over time but in either case they are damaging both to product quality and to furnace internal components. In extreme cases, the problem is obvious: the furnace will not pump down and/or the hot zone (or heating elements) shows obvious signs of attack. Tiny leaks, however, are more common often going undetected because of the pumping systems ability to overcome them. However, even small leaks can cause continuous and sometimes catastrophic damage. Thus, routine leak checking and leak repair should be a part of any good vacuum furnace maintenance program.
One of the most widely used charts in the field of brazing is the strength vs. clearance chart created from work done in the Handy & Harman laboratories in Fairfield, Connecticut back in the 1930's. Notice that as the joint clearance gets tighter and tighter (moving from right to left along the bottom axis), the tensile strength (as shown on the vertical axis on the left-side of the chart) gets higher and higher. Although there is a lot of experience with this over the years, and general acceptance of this information is widespread, it must be pointed out that this chart is very specific only to the actual testing performed in making this particular chart, and may not be identical to tests performed by others using similar materials or conditions. But the general principal of increased joint strength with tighter gaps can be accepted.
Aside from the well-known grain size measurement techniques using either the planimetric methods of Jeffries or Saltykov, or the intercept method of Heyn, Hilliard and Abrams, one can measure the grain size through a count of grain-boundary triple point intersections within a known area through the use of Euler’s law. This technique has rarely been used but it should be possible to do such a count by image analysis. In general, measurements based on point counts (0 dimensional) are less subject to errors than lineal measurements (one-dimensional) which are less subject to error than areal measurements (two-dimensional).
Vacuum gauges measure the pressure readings in the range from atmospheric pressure down to some lower pressure approaching absolute zero, which is not attainable. Some gauges read the complete range with low resolution and others can only read a portion of the range but with better resolution, usually used for the lower pressures. There are three groups of vacuum gauges based on the method of operation, mechanical, thermal conductivity and ionization. For this discussion we will only talk about the thermal conductivity and ionization gauges because purely mechanical vacuum gauges are generally not used on vacuum furnaces.
Titanium has many attributes that are useful in today’s modern society. It is a relatively lightweight, corrosion-resistant structural material that can be strengthened dramatically through alloying and, in some cases, by heat treatment. Among its many advantages for aerospace, military and commercial: good strength-to-weight ratio, low density, low coefficient of thermal expansion, good corrosion resistance, good oxidation resistance at intermediate temperatures, good toughness and (relatively) low heat-treatment temperatures.
This series of articles focuses on the return of investment of particle diagnostic equipment. The first two articles focused on the “easy” applications – applications that proposed payback through comparison of results, recognizing questionable results compared to ones of a “known preferred or specified result”. A thorough understanding of each measurement or the measurement process and the precision of the measurements to some extent could be overlooked. Subsequent to the first three articles, articles 3 and 4 require more precise measurements and will require a better understanding of the measuring processes.
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.