What Does Statistical Process Control Really Do? (Part 4)

Posted by John Clemons on February 28, 2013 @ 9:52 am

Well, I was pretty certain that my last post on SPC was going to be my last post on SPC (if you follow my meaning).  But, I kept getting lots of questions from a lot of people who were very interested in SPC and I said I would do my best to address at least some of their questions. What I think might be the best way to wrap up this discussion (and I really do mean this to be my final post on SPC) is to simply stick with the idea of SPC in the real world and give you some simple real world examples of how I’ve used SPC in the past. Continue Reading

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3 Basic Elements of Advanced Process Controls

Posted by Bruce Brandt on February 26, 2013 @ 10:53 am

With the increase in processor power, the number of advanced process control (APC) algorithms available to users has reached a level where everyone should be considering if they can improve their operations by adopting one or more of the strategies. However, in some older plants, a cascade or feed forward control loop could be considered advanced control. So what really constitutes advanced control? The usual suspects involve fuzzy logic, neural networks and predictive modeling, but there are other opportunities to improve control without resorting to something your staff may struggle to understand and use. Let’s look at three basic elements of APC. Deadtime compensation is one of the advanced control concepts that is not very well understood. Many think that simply inserting a deadtime function block into the input to the loop is adequate, but doing so neglects the effect of proces... Continue Reading

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What Does Statistical Process Control Really Do? (Part 3)

Posted by John Clemons on February 21, 2013 @ 9:16 am

SPC Really Do Part 3I think this is probably my last post on the topic for SPC, at least for awhile.  I really didn’t plan on having this one, but in putting together my first two posts, a several people asked me a lot about what the SPC really look like and what you really need to implement SPC.  And, since I mentioned the concepts of real-time SPC and historical SPC in my previou... Continue Reading

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The Benefits Of Reusing Control Logic

Posted by Matt Dougherty on February 19, 2013 @ 9:49 am

The first large project I worked on in my career taught me that reusing code isn’t just a way to get more done with less effort; it is also makes problems that have nothing to do with the code very obvious. Let me explain: The project was a new 40 million gallon-per-day wastewater treatment facility in South Carolina. The commissioning of the plant went very well, and all systems checked out. A few weeks after commissioning, I was sent back to the plant because they were having a problem with their effluent pumps. Three effluent pumps were set up in a lead-lag configu... Continue Reading

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What Does Statistical Process Control Really Do? (Part 2)

Posted by John Clemons on February 14, 2013 @ 8:24 am

From my last post on this subject, you should probably think that statistical process control (SPC) is pretty cool, and pretty valuable, as long as you don’t think too much about all the math.  (Actually, the math is pretty cool as well.)  But, SPC is not for everybody and it not the cure all for everything that ails you or your manufacturing process.  So, I’d like to talk about ways to know whether or not you’re really ready for SPC. Continue Reading

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