An instrument — such as my trusty Simpson 260 volt-ohm-milliammeter — doesn't require calibration because I use it for gross measurements. But engineers must calibrate lab instruments such as oscilloscopes, digital voltmeters and signal sources used for precise measurements. When a calibration comes due, an instrument — even a PXI or VXI plug-in instrument — goes to an accredited calibration lab. (I'll discuss calibrations more in another column.)
Although measuring-equipment manufacturers specify calibration intervals, typically a year or less, engineers might need to calibrate instruments at other important times, particularly:
When measurement values vary from what you routinely observe or when results seem unusual. These types of observations might signal a need for repair or a thorough clean-out of dust and grime followed by a calibration. Remember, components age so older equipment can need more frequent calibration than newer instruments.
When an instrument experiences rough handling or damage. If a pair of pliers falls on your sensitive DVM or source-measure instrument it shouldn't need calibration. But if the DVM drops off a shelf onto your bench, consider calibrating it. (If you send instruments off-site for calibration, pack them carefully and ensure the cal lab does the same.)
When you start a high-value project. You don't want to get deep into a prototype design only to find you've reported inaccurate test values. Of course you won't know you have bad values until someone tries to duplicate your results or a final design doesn't perform as expected. Some companies might recommend calibrating instruments at the end of such a project, too, just to verify the accuracy of your measurements. A cal lab typically provides a calibration report that includes "as received" information. If the instrument performs within spec, the lab won't perform the associated calibration. Labs also report measured "as sent" information so you know the state of your instrument when it left the lab.
When a contract stipulates instrument calibration. A contract between a company and a university research lab could require calibration of instruments at specific times or by a specific lab.
When production-test equipment produces too many false passes (bad products that test well) or false failures (good products that test bad). No company wants angry customers with faulty products or a rework line jammed with good parts awaiting unnecessary repairs and retesting. You can use statistical process-control (SPC) software to help detect false-pass and false-fail results.
As Sir William Thomson, Lord Kelvin, said, "If you cannot measure it, you cannot improve it." So ensure you keep calibrations up to date.
The engineers and inventors of the post WWII period turned their attention to advancements in electronics, communication, and entertainment. Breakthrough inventions range from LEGOs and computer gaming to the integrated circuit and Ethernet -- a range of advancements that have little in common except they changed our lives.
The age of touch could soon come to an end. From smartphones and smartwatches, to home devices, to in-car infotainment systems, touch is no longer the primary user interface. Technology market leaders are driving a migration from touch to voice as a user interface.
Soft starter technology has become a way to mitigate startup stressors by moderating a motor’s voltage supply during the machine start-up phase, slowly ramping it up and effectively adjusting the machine’s load behavior to protect mechanical components.
A new report from the National Institute of Standards and Technology (NIST) makes a start on developing control schemes, process measurements, and modeling and simulation methods for powder bed fusion additive manufacturing.
If you’re developing a product with lots of sensors and no access to the power grid, then you’ll want to take note of a Design News Continuing Education Center class, “Designing Low Power Systems Using Battery and Energy Harvesting Energy Sources."
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.