Note that double-ended shear beams are practical for applications with very large loads but size constraints this is because they have higher load capacity ratings than single-end shear beams, and are less bulky than equivalently rated canister load cells. The load should not shift relative to the cell body. Likewise, when using double-end shear beams, align the load vertically through the center, avoiding twisting or torsion. As described in Section 4, install rod-end bearings and clevis mounts to prevent this. This will maintain axial loading.Ī failure to maintain axial loading could result in bending moments. Also, the load path should be perpendicular to both plates. The top plate that will translate the load should consistently be parallel to the bottom plate. When installing shear beams, single-point (platform), canister, and diskload cells, keep the lower mount plate level and flat. When using load cells under structural supports, always arrange them on a level plane perpendicular to the force flow, and spaced at equivalent angles and distance from the center of force. While some manufacturers recommend placing “dummy” cells on supports and deriving the total load, dummy cells can prevent proper calibration. Place load cells at all corners of the supporting structure to maintain the full weight or load. Section 4 describes mounting best practices to mitigate improper loading. Since loads can be compressive, tensile, or torsional, properly guiding the load direction depends on the application. The most common reason for inaccurate load cell measurements is improper axial loading. (a) Correctly Distribute and Guide the Load Misaligned loads can happen in two ways: (a) when the frame and mounts improperly guide the load and (b) when any attached structures (such as supports, safety cables, pipes and hoses) create “force shunts.” This FAQ explains the effect of improperly guided loads on the load cell reading. Also, the load’s geometric center must be over the load point, not just aligned in the proper direction. This axis is often clearly marked on the device and is typically perpendicular to the loading surface. If the measured force is not fully applied through the load cell’s intended axial direction, the measurement system won’t capture the correct reading. Ideally, in a measuring system all of the load or force will be transmitted through the load cell. Particularly in outdoor environments, the support frame should account for other forces that can add loads to the system, such as wind. (c) Avoiding Rotationįor suspended loads, the mounting frame should limit rotation to prevent hardware from loosening over time. Also build a frame that avoids the intrusion of ice, moisture and other weather-related factors that can cause corrosion or mechanical deformation. To maintain a safe operating environment, always design for the appropriate amount of expansion clearance. Load cell mounts that do not allow for mechanical expansion can cause permanent damage to the load cell or frame. (b) Accounting for Thermal Expansion/Mechanical Deformationĭesign the mounting frame to allow for unhindered thermal expansion or contraction. To the extent that vibration mitigation is not possible, the measuring system should incorporate filters and software to compensate for the effect. Securing the frame to a hard, flat surface will reduce vibrations from passing vehicles and local equipment. Additionally, ground vibrations from seismic activity can skew measurement results. (a) Mitigating VibrationĪ variety of sources can introduce vibrations that affect the fixture, including compressors, pumps, actuators, and engines. Vibrations, thermal expansion, mechanical deformation, and stray electrical current can cause false readings and damage to, or failure of, the load cell. The fixture design should minimize unintended inputs from the surrounding environment.
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