Load cell assembly 101
Properly installing a load cell ensures that the sensor provides the most stable readings and accurate measurements possible. Although a load cell operates regardless of its orientation and operation in tension or compression mode, there are specific assembly instructions for each sensor model.
Interface provides complete product data sheets and drawings to find the features for assembly. Our instructions include model, material, capacity, mounting holes, threads and dowel pins, as well as pilot specifications for live and end-of-line use.
All load cells have a “dead” end and an “active” end. Typically, the “dead” end is the mounting end that connects directly to the output cable or solid metal connector. Conversely, the active end is marked by the Strain gauge area of the bending part is separated from the output cable or plug.
This concept is important because mounting a cell at the active end causes it to be subjected to forces created by moving or pulling the cable. However, dead end mounting ensures that the forces acting through the cable are dissipated to the bracket rather than being measured by the load cell.
SPECIAL INTERFACE LOAD CELL MOUNTING TIP: The Interface Load Cell nameplate can be read correctly when the dead end cell is on a horizontal surface. Therefore, the user can use the nameplate label to explicitly communicate the required alignment to the installation team. For example, in a single cell installation that holds a container under tension to a ceiling joist, the user would mount the cell so that the nameplate is upside down. For a cell mounted on a hydraulic cylinder, the nameplate would be read correctly when viewed from the end of the hydraulic cylinder.
WATCH: ASSEMBLY TIPS FROM OUR WEBINAR ON LOAD CELL BASICS
Determine your assembly requirements
Mechanical fastening is one of the most important aspects of the success of your application. This is a decision that depends on the sensor, as load cell models have different characteristics that can be used for different mounting needs.
First, decide how you want to attach your load cells. Should they be fastened with threads? Should the load cells be pressed against a surface? Do you use an actuator, rod ends or clevises?
Other mounting considerations include the items used to mount the sensor. Will you use glue? Is it mounted inline or do you need a through hole for mounting? Will you Mounting plates use, and what is the geometry of the plates? The material used and the rigidity of the mounting components can affect the performance and accuracy of the measurement. READ: Assembly of interface sensors and force plates
The direction of the load will affect your decision about the best approach. All load cells have an active end and a dead end. It is not a single direction; some active ends may be at the top or bottom. The design of the active and dead ends affects cable and radio management.
When applying torque when installing fasteners, it is important that you do not twist the sensor. Tip: Hold the load cell by the end where you are installing a fixture to avoid damaging the device.
Load cell adjustment surface tips
- The surface must be clean and even.
- The mounting surface must be level enough so that the total reading is 0,0002.
- Suitable thickness and material
- Recommended hardness of Rc 30 or higher
- Tighten the mounting screws according to the specifications
Installation care
Make sure the screw connections are tight and preloaded if possible. The preload eliminates system slippage and prevents wear, which is critical when using the sensor for fatigue testing. Bias is also important to maintain the performance specified in the calibration certification.
Make sure that the screw connections are tight and as preloaded as possible. The preload prevents the system from slipping and prevents wear, which is crucial when using the sensor for fatigue testing. Bias is also important to maintain the performance specified in the calibration certification.
Interface offers load cells with and without Plinth at. When supplied together, the base is designed to provide a suitable and “fitting” mating surface for the sensor. If you are using a load cell without a base, it is important that it is mounted similar to the base in terms of flatness, stiffness and thickness so that it does not deform under load. This is crucial to get the most accurate measurements possible.
Assembly checklist
- Load cells that are not assembled according to the manufacturer's recommendations may not meet the manufacturer's specifications.
- Ensure mounting surfaces are clean, flat and aligned.
- Tighten all fasteners to specifications.
- Always check the orientation of the load cell: the “dead” end to a mechanical reference or power source and the “active” end to the load being measured.
- Typically, the dead end is the end that is mechanically closest to the cable exit or connector.
- Use the correct fasteners (thread sizes, lock nuts and swivels) to connect the load to the load cell.
- It is essential that there is only a single load path.
- This load path must run through the load axis of the load cell. This may sound elementary, but it is an often overlooked problem.
Applying best practices during assembly is also extremely important. Distractions in the system can introduce errors and apparent crosstalk into the sensor measurement.