| When I was a kid I had a toy robot that captured my attention like no other toy. I thought it was so cool to have something animated that looked both humanoid and machine-like at the same time. It couldn’t do much, just walk in a stiff, jerky way and move its arms up and down, but that was enough to keep me fascinated.
Today’s generation of robots do not often take on the humanoid form, but they’re capable of so much more. Robots on assembly lines perform a variety of tasks like welding and placing electronic components on circuit boards, and they do it much more quickly and accurately than any human could, so they’re often employed in manufacturing. We’ve been discussing the Production stage of the systems engineering approach to medical device design. We learned that within the manufacturing process there are often opportunities for cost reduction, and today we’ll see how robots can be used to reach those goals. Last week we presented a sample scenario involving the manufacture of a percussion therapy device. In their quest to reduce manufacturing costs, engineers identified bottlenecks along the assembly line which led to idle worker time and the inability to keep up with orders. In addition to these production woes, it was discovered that the tedious, repetitive manual labor that occurred at each bottleneck created opportunities for assembly mistakes. As many as 30 devices per day were being rejected by quality control inspectors due to issues such as faulty wiring and improper parts usage. This led to expensive rework to correct mistakes. After further evaluation, design engineers determine that bottlenecks can be eliminated by installing automated assembly equipment in the three distinct assembly stages represented on the line, those involving wiring harnesses, printed circuit boards, and the motor drive mechanism. The potential for human error is high during many facets of manufacturing, and this can be minimized or eliminated through the use of robots, that is to say, mechanized equipment capable of automatically performing a complex series of specific tasks. These robots never tire of performing tedious, repetitive work, and their efficiency is unparalleled. Their introduction at key junctures on the assembly line has benefits across the manufacturing process, enabling workers to keep continuously busy and reducing the incidence of human error. The introduction of robotics is known as industrial automation. Robots efficiently increase manufacturing speed, and along with it profits, so their introduction more than compensates for the investment costs associated with purchasing them. Next time we’ll continue our look at the Production stage to discover another way that systems engineering can simplifying the assembly process, by eliminating some functions altogether. ___________________________________________
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Posts Tagged ‘mechanized equipment’
Systems Engineering In Medical Device Design – Production, Part 3
Sunday, March 10th, 2013
Industrial Control Basics – Pushbuttons
Monday, December 26th, 2011| I always enjoy watching impatient people waiting for an elevator. They press the button, and if it doesn’t come within a few seconds they press it over and over again, as if this will hurry things up. In the end they must resign themselves to the fact that the elevator will operate in its own good time.
Pushbuttons, although simple in appearance like the big, red “Easy” button that’s featured in a certain business supply chain’s commercials, are actually complex behind the scenes. They perform important functions within the industrial control systems of a huge diversity of mechanized equipment. Last week we introduced ladder diagrams, used to design and document industrial control systems, and we’ll now see how they depict the action of pushbuttons within two commonly used industrial settings, the “normally open” and the “normally closed.”
Figure 1
Figure 1(a) shows a pushbutton hooked up to an electric motor. When no one is pressing it a spring in the pushbutton forces the button to rest in the up position, allowing an air gap to exist in the electrical circuit between hot and neutral and preventing current from flowing. This type of switch is characterized as a “normally open” switch in industrial control terminology. In Figure 1(b) someone depresses the button, compressing its spring and closing the air gap, which allows current to flow and the motor to operate Figure 1(c) shows the ladder diagram version of 1(a). Now let’s take a look at Figure 2 to see a different type of pushbutton, one that’s characterized as “normally closed.”
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