The topic of “Process Control and Instrumentation” (PC&I) is strongly affected by technology changes. Sometimes it feels as if you need an electrical-engineering degree to wade through it all. Changes in specifications such as AMS 2750 also create uncertainty as to what is required and what is simply a nice-to-do. Check out the reader-chosen articles in this list to find some help.

Topics such as AMS 2750 always generate lots of reader interest. So, it’s not surprising there are several AMS 2750-related articles on our favorites list. This, along with keeping up with new technologies, is what readers seek. Let’s take a look at the current favorites from first moving to number eight.

Illustrating the industry’s need for AMS 2750 information, an article written in January 2014 still leads our PC&I list. The article discussed the top-10 Nadcap nonconformances at that time, eight of which involved pyrometry. Apparently, the industry’s attempt at clarifying the requirements for aerospace primes has created new auditor fodder. Check this article out to see how you can avoid some of the traps that have ensnared others. Find it using this easy link www.industrialheating.com/AMS2750.

Thermocouple (T/C) failures can be a huge problem for manufacturers, and this relates to some AMS 2750 requirements. How do you know when it failed, and how much product might be affected by the failure? Find out which T/C materials are best for your application and how design can affect longevity of the probe.

System wiring and electronics play a role in failures. It’s important to understand probe life in your application because you may choose to replace a T/C early rather than risk failure and its associated costs. Finding the true root cause for a thermocouple failure and eliminating it is important. It can lead to cost savings and reduce system downtime. Read more at www.industrialheating.com/TCfail.

Are we using the instrumentation technology that will save us the most time and money and make it easier to meet requirements such as AMS 2750? This type of question causes readers to seek out information. As a result, this article from 2013 continues to be a reader-favorite. It discusses topics such as wireless technology, touch screens and cybersecurity. Part of the article’s conclusion says, “When deciding on new instrumentation, it is critical that newer technologies are considered because they may become mainstream in the future.” You can find this article at www.industrialheating.com/newtech.

Accurate measurement of any heat-treating atmosphere is critically important for the quality and process yield of heat-treated components. Dew-point analysis has been a traditional measure because moisture parameters can impact carbon potential. However, a better, more-robust instrument was needed to analyze endothermic or exothermic atmospheres. Oxygen probes or three-gas analyzers are now the industry’s preferred analytical instruments to determine carbon potential.

The article’s conclusion states, “When vacuum heat treating metal alloys that oxidize readily in the presence of small concentrations of water vapor or oxygen, data suggests that dew point should not be the stand-alone gas purity analyzer. Dew point only measures the water vapor, not oxygen in the gas line. Including an oxygen analyzer as an additional quality tool provides the heat-treat shop greater assurance that the process gas entering the furnace is of the highest purity and meets the specifications of the customer.” Find out what’s drawing readers by reading this article online at www.industrialheating.com/DPvO2.

Another AMS 2750 article from May 2013 remains in the top-8. One of the challenges with AMS 2750 throughout the years is that changes are typically not highlighted from one rev to the other because they are too numerous. The latest revision is no different. SAE includes numerous technical changes to resolve issues determined in usage. However, one of the challenges as specifically noted in this latest revision is that the “Changes are extensive and not marked.” As a result, users who are subject to compliance with AMS 2750E must take the time to review the most recent revision thoroughly.

This article provided and continues to provide assistance by highlighting some of the more significant changes in AMS 2750E as they relate to temperature sensors. You can benefit from this work at www.industrialheating.com/2750revE. Another article from 2013 provides additional assistance at this link: www.industrialheating.com/2750E.

Many factors, including pyrometer choice, emissivity and temperature calibration, influence accurate temperature measurement from a pyrometer. This May 2016 article looks at the common influences on inaccurate temperature measurement.

The following questions are answered: What wavelength of detector is used for a given temperature range? What detector wavelength should be used for an application? Why calibrate pyrometers? Why do pyrometers drift? How often should pyrometers be calibrated? Why calibrate to a traceable national standard? To learn these answers and more, read this article at www.industrialheating.com/Tcorrect.

As some of our other PC&I favorites discuss, oxygen probes, PLC and microprocessor controls, digital charts and even database management have seen technology improvements. One area that has not experienced this is the temperature uniformity survey (TUS). This periodic test determines the ability of the furnace to be able to process work for CQI-9, Nadcap and other quality-system requirements.

As already discussed, meeting the requirements of AMS 2750 has become the bane of quality departments and the focus of auditors for decades. While data loggers have replaced the tedious task of recording individual temperature readings over time, they do not fit into the advanced world of Big Data. Real-time data collection of part dimensions, tool edge wear and even Rockwell hardness is quickly moving ahead, but the TUS is lagging behind.

Check out this November 2016 article to learn about the Virtual Visual Survey and why it may transform TUSs and make them compatible with the industrial internet of things (IIoT). You can link to the article here: www.industrialheating.com/VVS.  

Furnaces are built and tuned for a variety of heat-treating processes, including: carburizing, carbonitriding, ferritic nitrocarburizing (FNC), annealing, tempering, nitriding and vacuum heat treating (among others). These processes require different types of gas generation; soak and quench times; and atmosphere and temperature control. In spite of the different requirements, control of these processes can be divided into two general categories: traditional and automated.

This August 2014 article discusses automated heat-treat processes, breaking it down into technology and productivity gains, data acquisition and benefits to maintenance. Should you automate your traditional control? The authors believe you should, and you can learn why by reading this article at www.industrialheating.com/htcontrol.

There are some very helpful articles in this selection. Especially if you missed them the first time, you owe it to yourself to have another look.

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