Category Archives: Mechanical Engineering

I’m convinced that in my job, I use 95% of the material covered in engineering school less than 5% of the time. Most of what I do boils down to on the job experience or falls in the category of project management.  In many cases, not much would separate me from a talented hobbyist or tinkerer. Of course, this makes me question the value of my education. Why did I spend all that time learning all that stuff? I’ve considered it for a while, and I like to tell myself that the 5% of the time I really use my degree is what makes me valuable as an employee. In a tangential line of discussion, there’s also been a fair bit of talk in the news recently about the workforce, the number of engineers trained in the US, and why so many STEM students change majors. One line of reasoning…

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It seems like I spend an inordinate amount of time trying to convince others of my ideas. Or sometimes it’s my boss’s idea that I’m trying to get across to another department. One interesting thing I’ve found is that people are especially critical if your idea steps on their specialty. I’ll give you an example. A lot of folks where I work have pretty good machining experience. They’re very familiar with various finishes and also with welding specifications. If you’re presenting a machined part with some welds and a finish call out they will quiz you non stop on why you chose that material and that finish over any other. But they are a lot less familiar with various electric or electro-mechanical processes. In my mind the finish I chose for a machined part is just as obvious as what kind of shielding and sleeves I’m using to protect the wiring harness.…

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Last semester, I started my first official school year off teaching a senior level undergraduate class. This was a required course that was, from my understanding, a softball in recent years. I decided that I needed to set a different tone for the class than what might have been set in previous years. Incidentally, that tone got me quite a lot of “not very approachable” reviews on my semester student ratings. I find that odd because I never turned away a student from my door and I answered emails all throughout the night. Shrug. But I digress… This semester, I’m teaching a grad class of my design. And there are two distinct differences from teaching an undergraduate class: 1) it’s a free-for-all on material and 2) I find that I’m much more lackadaisical about grad classes. I’ll expound on those thoughts, reverse chronologically because it makes more sense that way. Lackadaisical Approach…

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Failure is not always a bad thing. Sometimes it’s exactly what you want. You might start with one component that’s been well tested with the existing system. It can be a simple clamp or a complicated swing valve (like the one pictured from DHV Industries). You probably tested it out when it was originally implemented and proved you had plenty of safety margin. But now your system has changed. Maybe you’re sending your system into freezing winter temperatures or hot, arid deserts. Maybe you’ve got a more powerful compressor that generates much higher pressures than you’d been dealing with before. So how do you test that component? Most standards would suggest you take your max operating conditions and increase the magnitude by 50% and test at those conditions. That proof test would verify your equipment can operate safely at your max conditions giving you a 1.5 safety margin. But in…

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I talked last week about increasing fuel economy standards in the US and how our engine designs have been improving incrementally to meet this new demand. It was almost a year ago that I talked about the military’s affection for diesel in a wide variety of platforms. Well now it seems like the flexibility of diesel and the American consumer’s desire for better fuel efficiency is meeting somewhere in the middle. When Americans think about diesel they might have an image in their heads of 1970s diesel cars puffing black smoke everywhere or a smelly large truck. Diesel is extremely popular in Europe but their environmental and safety standards are different which prevented direct injection (ha!) of European diesel cars in to the US (like the direct injection of the Bosch common rail injector in the photo). Still the advantages in fuel economy with the models we’ve been seeing so…

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The internal combustion engine has been around for several hundred years and been used successfully in industry and commercial applications for more than one hundred years. When we think about cutting edge technology we tend not to think about things that have been around that long. And in fact, most of the design of the engines we use today have not changed substantially in decades. But that doesn’t mean the small changes we are working towards don’t have dramatic effects. (Photo via creative commons from Ranj Niere) The auto industry has voluntarily agreed to meet new fuel efficiency standards of 55 mpg fleet average by 2025. Yes you can reread that, they voluntarily agreed. So why? Don’t more stringent fuel efficiency standards make car design and manufacturing more expensive? Yes and no. Yes it make it more expensive, but manufacturers know that demands for better gas mileage from consumers will…

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Most designs are a solution to a problem. But a lot of times you can’t always solve the problem the way you want. The ideal solution might require a redesign of interconnecting parts that you can’t necessarily change. Or it might require time to test components that you don’t have. Sometimes you have to pick the next design iteration because it’s available or works within your time frame. But how can you be sure you’re not sacrificing the best solution for something that’s easy? Sometimes you need to have an interim solution. Sometimes you do have to make the quick and dirty choice while still working towards something long term. I’ve had several problem child pieces of hardware lately and this decision has come up several times. Often I’ve been forced to come up with a practical quick fix. It’s tough when you do that to keep the momentum up…

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There’s a phrase: jack of all trades master of none. I was thinking of one’s progression as an engineer. When you graduate college you are in many ways like a Swiss army knife (drawing from rowland jones). You have a wide variety of basic tools but are probably not particularly good at any one thing. In many ways college teaches one the ability to learn engineering. And then you spend the rest of your career learning engineering. But at some point you have to start narrowing it down. Especially if you are, like me, a mechanical engineer or as one of my classmates put it a mercenary engineer. My degree qualified me to work in any number of disciplines: mechanical systems, fluids and heat transfer, structural analysis, flight and aerospace technologies, and manufacturing. The first job you take can often lead you down the path of a particular discipline within your…

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It began as so many engineering projects do – the simple thought, “you know, it wouldn’t really be ALL that hard to do….” One of my good friends drinks a lot of carbonated water, and on her wish list is a Sodastream carbonation system. I looked at those online, and it offended my open-source sensibilities that you have to buy the filling station, the proprietary CO2 bottles, the proprietary flavoring, and the proprietary bottles to fill. Really, I thought, one should be able to buy a tank of CO2, some appropriate fittings, and do this a whole lot cheaper. Now I really don’t drink much soda, nor do I care for carbonated water, but as an engineering project this fascinated me. There are even excellent tutorials already available online on this very subject. I walked myself down the street to the welding supply shop (I love living near a technical university…

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While I would really have loved the title to be a pun on signal processing, I have to admit that today’s post is not about that esteemed branch of electrical engineering.  Instead, I’m going to talk about mixed messages I’ve been receiving. I had some colleagues from our university career center come and speak to students last week about the services they offer.  Recently, the career center held a job fair, and one of the speakers said that many of the companies asked her where all the electrical engineers were.  Apparently, the midwest has really had some serious job growth since the economic downturn in 2008, and there just aren’t enough students for internships and maybe even jobs. While I appreciate that being the perspective from a career counselor, I spent a bit of time looking over the engineering entry in the occupational outlook handbook compiled by the Bureau of Labor…

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