| 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 ‘assembly line’
Systems Engineering In Medical Device Design – Production, Part 3
Sunday, March 10th, 2013
Systems Engineering In Medical Device Design – Production, Part 2
Sunday, March 3rd, 2013| Last time we began our look at the Production stage of systems engineering. We learned that cost reduction is a frequent component of this stage due to market fluctuations and ongoing stakeholder requirements to cut costs, and that savings can be made through substitution of plastic for metal parts. In fact, there are many faces to cost reduction. We’ll explore another of those today.
Cost reduction isn’t limited to material expense. Within the manufacturing process itself there are often ample opportunities for cost reduction. As an example let’s say we’re manufacturing a medical device known as a percussion therapy device on an assembly line employing 21 workers over three shifts. This line assembles 300 devices per day at a combined material and labor cost of $2,100 per unit. Percussion therapy devices are frequently used within the medical setting as they perform the very important function of helping to dislodge mucous from patients’ lungs. As such, they are in high demand and the market for them competitive. In our scenario some stakeholders in the device’s manufacture, in this case sales and marketing managers, specify that a cost reduction of $200 per device is necessary to avoid losing ground to competitors. In response to this directive, design engineers take a fresh look at the assembly process. They identified several bottlenecks at key junctures during which manual labor is involved. They note that due to the painstaking work required at these stages, production is slowed. Assembly lines operate dynamically, meaning any disturbance in the flow of activities has vast repercussions down the line. Bottlenecks in flow slow production lines, just as they do traffic on key arteries. A tie-up on assembly lines equates to production delays, and these may lead to difficulty in filling customer orders. Impatient customers have been known to turn to competitors when their orders aren’t filled, and this translates to lost revenue to our manufacturer. Next week we’ll see what manufacturing changes are employed to solve identified problems, and we’ll see how man’s best friend is not a dog, but a robot. ___________________________________________
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Industrial Control Basics – Manual Control
Monday, December 12th, 2011| You’ve probably heard the saying, “asleep at the switch.” It’s usually associated with some sort of disaster, found later to have been caused by human error. Someone wasn’t paying attention, and something very bad happened. The meltdown of the Soviet nuclear power plant Chernobyl in 1986 comes to mind. You may be surprised to learn that the saying has its origins in the world of industrial controls, or more specifically, manual controls, as we’ll see in this article.
Last week when we opened our discussion on manual controls, we talked about how they work just as their name implies, that is, someone must manually press a button or throw a switch in order to initiate a factory operation. In other words, a manual control requires human intervention to initiate an action, such as pushing the start button. The machine will then continue to run until a person hits the stop button. Let’s go now on a virtual field trip into a telephone factory to see how a basic manual control system works. It has a conveyor belt operated by an electric motor, and this motor is connected by wires and a power switch to a 120 volt power source of alternating current. Figure 1 illustrates what we mean. It shows that when the power switch is in the open position, a physical air gap exists within the electrical circuit. This prevents electricity from flowing through the wire because electricity can’t jump over gaps.
Figure 1 – Open Power Switch Enter a human into the scenario, someone who grabs the power switch handle and manually closes it, eliminating the air gap. See Figure 2.
Figure 2 – Closed Power Switch When the power switch is closed, a metal conductor bridges the gap, causing electricity to flow through the metal conductor to the electric motor in the circuit. This brings life to the conveyor belt. As long as the power switch remains closed, the conveyor belt will continue to operate. That’s it, that’s a basic manual control system. It’s simple to operate, but it does have one major flaw. It requires constant monitoring by a human. Aside from opening and closing a power switch, humans are required to monitor operations, in case something goes wrong. The operator watching over an industrial machine performs the same function as the pilot on a plane, that is, to start-stop operations, and to intervene in case of an emergency. Computers fly modern jets. Pilots serve as trouble shooters when the unanticipated disaster situation occurs, because computers can’t yet creatively problem solve. Next time we’ll introduce the element of an automatic control system, which will virtually eliminate the need for human intervention and with it human error. ____________________________________________ |
