Why should I use semiconductor strain gauge load cells as opposed to foil gauge units?
Semiconductor strain gauges provide greater durability, longer service life, and have a very low noise output. Semiconductor gauges have also been tested to have about 25 to 50 times the amount of electrical outputs of foil gauges when a strain is applied.
Foil gauges remain popular due to their lower cost and ability to be less affected by environmental temperature shifts. However, the benefits of foil gauges as it relates to temperature changes are only seen when extreme temperature swings occur, which is often not the case within most shops.
The major advantages to semiconductor strain gauges fall under six categories: noise, range, overload protection, service life, hysteresis, and repeatability.
Noise: random, non-grounded electrical signals produced by the components on the machine that interfere with the tension signal produced by the load cell. Because foil gauges require higher amplified signals due to their low output, even slight noise becomes amplified thus making your machine more susceptible to tension changes as a result of increasing or decreasing noise rather than your application process. Because noise is an unavoidable fact, the less affect it has on your load cells the more precise and accurate your application is.
Range: Due to foil gauges susceptibility to noise, they are not as reliable at low tensions, as their smaller signal can be lost amongst the noise. Semiconductor gauges are able to maintain their precision and accuracy in much wider tension ranges, whether very low or very high.
Overload Protection: Because semiconductor strain gauges are more sensitive to slight changes in tension they require less strain to produce a signal. Foil gauges are required to operate closer to their yield to produce a large enough signal for use and thus bend more. Semiconductor gauges can accept greater bend/overload making them more reliable and have a longer service life.
Service Life: Because foil gauges are required to work closer to their yield point to produce usable signal their service life is greatly diminished when compared to semiconductor gauges which rarely if ever approach their yield point. This allows semiconductor gauges will wear out over their natural life span which often extends beyond 4-5 years.
Hysteresis is the difference in values in actual tension from desired tension as reported by the load cells. Total hysteresis is measured through the device output when increasing and decreasing tension for the same tension level. Foil gauges have been measured to have a larger hysteresis then semiconductor gauges thus do not produce the same levels of repeatability as semiconductor gauges decreasing overall accuracy and precision.
Repeatability is the ability of a load cell to consistently provide the same signal for the same amount of tension being used. Ex: 50 lbs of tension appears as 50 each time. Not 45 one time and 55 another, etc. Because of the hysteresis benefits of semiconductor coupled with the manufacturing benefits (semiconductor gauges only have a single layer of adhesive between it and the beam, whereas foil has two) semiconductor gauges have much higher rates of repeatability.
With all that said not all semiconductor strain gauges are created equal amongst manufacturers. Montalvo has maintained its reputation over the years for producing some the industry’s most sensitive, accurate, precise and long lasting load cells. Always ensure you are using the very best for your application.
Check out all of Montalvo’s Semiconductor Strain Gauge Load Cells.
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