Posts Tagged ‘rework’

Systems Engineering In Medical Device Design – Production, Part 3

Sunday, March 10th, 2013
     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.


Medical Device Manufacturing

Systems Engineering In Medical Device Design – Instructions, Part 3

Sunday, January 20th, 2013
     Last time we looked at the objective of the quality control department in the Production stage, that being to ensure that the end product produced fits all requirements.  We learned that to meet this objective a great deal of collaboration must take place in the Development stage between quality control staff and design engineers in order to produce a complete set of instructions for quality control inspection and testing.  Now let’s see how these instructions are developed.

     Inspection and test methods are devised by the quality control department to ensure that a completed medical device lives up to its intended use.  What good is a diagnostic imaging machine that doesn’t provide accurate internal views of a patient’s body?  Or a heart defibrillator that sends electrical energy pulses to a patient’s heart muscles when it’s not supposed to?  Quality control instructions are developed to guide inspection and testing methods so they’re performed correctly and consistently during the medical device Production stage.  The objective is to catch problems before they occur.

     For example, it can be specified that the plastic body components of a medical device be visually inspected after they are received from an outside vendor to check for undesirable defects, such as the presence of burrs, cracks, or non-uniform coloration.  If anomalies are discovered, they’re documented, and the components are rejected.  In other words, they are barred from being used in the assembly process.

     Quality testing methods are varied.  They may involve hooking up the completed medical device to test instruments to simulate all possible modes of operation and any anticipated glitches that may occur during testing.  While hooked up, the device’s operation is measured against key parameters to ensure that all is working well, and the data gathered is recorded and analyzed to see if operation is within normal limits.  For example, an electric multimeter could be connected to the power cord of the device to measure how much electrical current is being drawn from the wall outlet during operation.  If current drawn is too high, it may be indicative of a defective electrical component, and an in depth examination would follow.

     Generally speaking, if test measurement parameters do not fall within acceptable limits as determined by previously established stakeholder requirements, then the medical device will be rejected by quality control.  It will then be sent back to the manufacturing department, along with a detailed inspection and test report explaining why it was rejected.  At this point the rejected device is either reworked or disposed of entirely.

     Next time we’ll continue our discussion on the development of instructions for the Utilization stage, the stage where the medical device is actually put into use by the end user.


Medical device engineering expert.