There are several ways to monitor loads in a press or punch inserting operation. Load washers, while somewhat insensitive to torque or other extraneous loads or moments, can have lower accuracy. Pancake load cells are more accurate but also much larger. A donut or thru-hole load cell offers reduced size with improved accuracy for these measurements.
Using metal foil strain gauge technology, FUTEK’s LTH300 miniature donut/thru-hole load cells address measurements from 50 to 1000 lb. Available in 17-4 stainless steel construction, the low profile (0.028-inch) units’ inner diameters range from 1/8 to 3/8-inch (3.40 to 9.80 mm) and the outside diameter is 0.98 inch (24.9 mm). With a rated output of 2 mV/V, the safe overload is 150 percent, zero balance is ±1 percent, and nonlinearity, hysteresis and non repeatability are ±0.5 percent of the rated output. Units have a nominal deflection of 0.002-inch, weigh only 2 oz (57 gm) and operate over a temperature range of -60 to 200F (-50 to 93C) with a compensated temperature range of 60 to 160F (15 to 72C).
In addition to a standard 10-ft long Teflon shielded cable with mechanical strain relief, available options include in-line signal conditioned, amplified or digital output, as well as an IEEE 1451.4 Transducer Electronic Data Sheets (TEDS) version. Other applications for this design include dual tank level control, tank dispensing and bag-filling machinery.