(Following is a response to a post by John Dodge on his blog “Design Engineering at Large” on March 12)
Your comment reflects the same eco nonsense that has been one of the biggest problems in making real progress. I’ll never forget on the first Earth Day, a science teacher at Pollard Middle School in Needham, MA, said that all plastics should be biodegradable and he halted a groundbreaking polystyrene recycling project at the school. The facts: Plastics should not be biodegradable because waste should not degrade in a landfill. They’re anaerobic: no air and no oxygen – and very little soil for that matter. We don’t want waste degrading and polluting aquifers, or creating gas clouds.
Ditto the Earth People’s drive to stop use of plastic foam cups for coffee. Those extremely useful and environmentally benign foam cups were replaced with double-strength bleached cardboard that don’t provide adequate insulation. And their net environmental impact was significantly worse than the foamed plastics they replaced, which by the way contained no chlorofluorocarbons or other damaging additives.
So you think that “all plastics should be recyclable”. Well in the first place most plastics used in packaging are very recyclable. The ones that aren’t are designed that way for a very good reason: they serve a useful purpose such as multi-barrier food protection that would require a huge output of energy to preserve foods if they were not used. More plastics are not recycled because It makes no economic sense to do so and the amount of energy expended in their processing and logistics more than outweighs any theoretical benefit in their recycling. Plastic recycling makes sense if you have a pretty clean stream of like materials. Like PET or high-density polyethylene bottles. Replace with paper? Paper processing requires trees; it requires those trees to be taken to an energy-intensive processing plant, which uses lots of nasty chemicals like chlorine which have been dumped en masse into the Great Lakes. Those paper products don’t degrade in landfills either. And when they’re burned in incineration plants, the chlorine gives off chemicals similar to those discharged by PVC. When you burn a polyethylene container in a waste-to-energy plant, you get a fuel source better than coal – but without the sulfur.
Are you getting the drift John? This is a complicated issue. I have just touched the surface here. What we don’t need our simplistic pronouncements, like we used to hear all of the time from the Greenpeace types.
A new service lets engineers and orthopedic surgeons design and 3D print highly accurate, patient-specific, orthopedic medical implants made of metal -- without owning a 3D printer. Using free, downloadable software, users can import ASCII and binary .STL files, design the implant, and send an encrypted design file to a third-party manufacturer.
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Capping a 30-year quest, GE Aviation has broken ground on the first high-volume factory for producing commercial jet engine components from ceramic matrix composites. The plant will produce high-pressure turbine shrouds for the LEAP Turbofan engine.
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For industrial control applications, or even a simple assembly line, that machine can go almost 24/7 without a break. But what happens when the task is a little more complex? That’s where the “smart” machine would come in. The smart machine is one that has some simple (or complex in some cases) processing capability to be able to adapt to changing conditions. Such machines are suited for a host of applications, including automotive, aerospace, defense, medical, computers and electronics, telecommunications, consumer goods, and so on. This discussion will examine what’s possible with smart machines, and what tradeoffs need to be made to implement such a solution.