Since brazing plays an important part in your company’s products, plan to have your staff attend one of the high-powered, three-day seminars being held in 2016. Our Brazing Seminars cover all the essentials for successful brazing of commercial and aerospace components. The improvements to brazing operations that have resulted from these seminars have paid for the cost of the seminar many times over at many companies! Register your staff today! They WILL truly benefit from having attended this program!
Next Seminar Date and Location: October 11-13, 2016 - Spartanburg, South Carolina
To Register on the Kay & Associates' Website CLICK HERE.
Last time we talked about the Kinetic Theory of Gases and how it can be used to calculate gas properties. We also considered the relationship between molecular density, mean free path, molecular velocity and pressure. Now we turn our attention to a discussion about temperature and kinetic energy, pressure and kinetic energy, and types of flow in vacuum systems. Again, we will focus on the basics, using fundamental comparisons to explain the concepts significant to industrial vacuum systems. Relevance of Temperature to the Kinetic Theory of Gases: Based on an atomic understanding of the world we live in, the Kinetic Theory reveals that gas properties are highly dependent on the speed of their molecules, which determines their kinetic energy, and therefore the gas pressure. When considering the effects of the Kinetic Theory, it is also important to understand the influence of temperature. Specifically, the speed of the molecules in a gas is dependent on its temperature (the higher the temperature the faster the gas molecules move). Another way to think of it is that the temperature of a gas is a measure of the average kinetic energy of that gas.
Over the almost 45-years of my brazing career I have discovered that there are a number of fundamental principles that must be understood and followed if successful brazing is to occur. Over the next few months we will look at each of these principles in more detail, but I will merely introduce them to the reader here. Brazing is a wonderful joining process, and also a forgiving process. By this I mean that even when you do not follow all the brazing principles exactly, brazing can work pretty well for you, but within limits. Gross disregard for some of these principles will, in fact, lead to failure of parts in the field (or in your brazing shop before parts are to be shipped to your customers) and are responsible for most of the problems people face with poor-quality brazed joints. By comparison, when people understand these principles, practice them well in their shops, they usually find that there are very few, if any, problems with their brazing operations and, as a result, their customers are quite satisfied with the brazed products shipped to them.
When ASTM standard E 2 was published in 1917, ASTM Committee E-4 on Metallography’s first standard, it described the planimetric method for measuring grain size based upon publications by Zay Jeffries, a founding member of E4; but, E 2 only briefly mentioned the intercept method developed in Germany in an appendix at the end of the standard. The intercept method suggested by Heyn in 1903  is considerably faster to perform manually which has made it popular, despite the fact that there is no direct mathematical connection between the mean lineal intercept length and G. Both straight lines and circles have been used as templates, plus other shapes. The Heyn Intercept Method - Modified by Abrams: In the 1974 revision of E 112 by Halle Abrams, he introduced the three-concentric circle test grid and a more formal methodology for performing intercept grain size measurements.
Most of us are familiar with processing in the vacuum range up to around 1.33 x 10-3 Pa or slightly lower. There are also lessons to be learned from understanding the demands of ultra-high vacuum applications. Let’s explore what’s involved. What is an Ultra-High Vacuum? Practical high vacuum levels range down to approximately 1.33 x 10-4 Pa while ultra-high vacuum (UHV) levels are in the vacuum range characterized by pressures of about 10-7 Pa and greater. These vacuum levels demand the use of special materials of construction and processing techniques such as preheating of the entire system for several hours prior to processing to remove water and other trace gases, which adsorb on the surfaces of the chamber. At these low pressures the mean free path of a gas molecule is approximately 40 km, so gas molecules will collide with the chamber walls more frequently than they collide with each other. Thus, almost all gas interactions therefore take place on various surfaces in the chamber.
Constructed of the finest materials and craftsmanship, VAC AERO’s high performance vacuum heat treating 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 and an 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.