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Load Cell Stiffness 101

Load cell stiffness refers to the ability of a load cell to resist deformation when a load is applied to it. It is a measure of how much a load cell will deflect or bend under a given load. Stiffness is an important specification of load cells, as it affects their accuracy and sensitivity.

Load cell stiffness is typically conveyed as the ratio of the load applied to the deflection of the load cell. For example, if a load cell deflects 1mm when a load of 100N is applied, its stiffness would be 100N/mm.

The selection of a load cell with an appropriate stiffness is critical to ensuring optimal performance in each application and should be carefully considered in the design and implementation of any measurement system. Load cell stiffness can significantly alter the performance.

High stiffness load cells are preferred in applications where high accuracy and precision are required, as they provide greater resistance to deformation and are less susceptible to measurement errors. High stiffness provides more precise and consistent measurements. They are the preferred choice for many applications, including in aerospace, robotics, material testing and of course calibration and metrology.

Low stiffness load cells may be used in applications where flexibility and compliance are necessary, such as in weighing systems that must accommodate vibration or movement. Load cells with low stiffness may be more suitable for applications where flexibility and compliance are important, such as in dynamic force measurement or shock testing.

The determination of load cell stiffness requires consideration of several key factors, including:

  • Load capacity of the load cell should be considered when determining its stiffness. Load cells with higher load capacities typically require greater stiffness to maintain their accuracy and precision under load.
  • Sensitivity of the load cell, or the amount of output change per unit of input change, should also be considered. Load cells with higher sensitivities may require greater stiffness to maintain their accuracy, as they are more sensitive to changes in the applied load. Read more in Load Cell Sensitivity 101
  • Environmental conditions in which the load cell will be used should also be considered, such as temperature, humidity, and vibration. In some cases, load cells with lower stiffness may be necessary to accommodate for environmental factors such as thermal expansion.
  • Application requirements specific to the use case, such as the required measurement range, accuracy, and resolution, will define the success of our project or program. Load cells with higher stiffness may be necessary for applications requiring high accuracy and precision, while load cells with lower stiffness may be more suitable for applications requiring greater flexibility and compliance.
  • Natural frequency, which is the frequency at which it oscillates when subjected to an external force is a consideration. Load cells with high stiffness have a higher natural frequency, which allows them to respond more quickly to changes in the applied force, resulting in faster and more accurate measurements.

Load cell design plays a critical role in controlling load cell stiffness. There are several key design factors that can affect the stiffness of a load cell, include material selection, geometry, strain gage placement and mechanical configuration. Read Get an Inside Look at Interface’s Famously Blue Load Cells to review our precision design features.

The choice of materials used in the load cell construction can have a significant impact on its stiffness. Load cells made from materials with higher Young’s modulus, such as stainless steel, are stiffer than load cells made from materials with lower Young’s modulus, such as aluminum.

Load cells with thicker walls, larger cross-sectional areas, and shorter lengths are stiffer than load cells with thinner walls, smaller cross-sectional areas, and longer lengths.

Strain gages placed closer to the neutral axis of the load cell will experience less strain and deformation, resulting in a stiffer load cell.

The mechanical configuration of the load cell, including the number and arrangement of its sensing elements, can also affect its stiffness. Load cells with more sensing elements arranged in a parallel or series configuration can be designed to be stiffer than load cells with fewer sensing elements.

Load cell design plays a critical role in controlling load cell stiffness to ensure that it meets the stiffness requirements of the application. If you have questions about the load cell that best fits your application, please contact us. Our experts are here to help.

ADDITIONAL RESOURCES

Interface Load Cell Field Guide

How Do Load Cells Work?

LowProfile Load Cells 101

Load Cell Basics Sensor Specifications

Load Cell Basics Webinar Recap

Interface New Product Releases Spring 2023

Interface continues to expand our product offerings of force measurement solutions. We have added new high-accuracy load cells, Bluetooth data loggers, indicators and load cell base kits. The following product summaries highlight the latest additions, along with product features for each model.  We also have a new torque couplings technical guide.

In our Interface New Product Releases Winter 2023 updated, we featured our Pillow Block Load Bearing Load Cells (PBLC).  We are excited announce that our PBLC series are now available in multi-axis options. Reach out to our application engineers to learn more about Pillow Block Load Bearing Load Cells 2-Axis custom options.

If you have questions about our new products, capacities, capabilities, or application uses, please contact our application engineers.

SSLP STAINLESS STEEL LOW PROFILE UNIVERSAL LOAD CELL

The Interface Stainless Steel Low Profile Universal Load Cell SSLP model is a low profile, pancake-styled load cells. The internal construction is a diaphragm design, offering a lower cost solution with high natural frequency, low deflection and excellent resistance to side and torsion forces. There is an optional mounting base available, required if used in tension testing. It provides high stability and low height. The SSLP can be supplied calibrated as a complete system with associated instrumentation. View: SSLP Stainless Steel Low Profile Universal Load Cell

Primary SSLP features and benefits:

  • Capacities from 2.5 to 5000 kN (562 to 1,124K lbf)
  • Low profile with stainless steel construction
  • Environmentally sealed to IP67
  • Hose and conduit fitting at cable exit
  • High thermal stability
  • Base options, including custom bases and custom top plate
  • Load cap assembly optional
  • TED options
  • ATEX and submersible versions available
  • Options for internally amplified and multiple bridges

BX6-BT PORTABLE 6-CHANNEL HIGH-SPEED BLUETOOTH DATA LOGGER

Interface’s digital instrumentation data acquisition system BX6-BT Portable 6-Channel High Speed Bluetooth® Data Logger is a multi-channel measuring amplifier that offers a multitude of features in a convenient compact package. The BX6-BT first channel is for full-bridge strain gages, channels two through six are individually configurable as voltage input (single-ended) or strain gage bridge input, including half and quarter bridge configuration. View: BX6-BT Portable 6-Channel High Speed Bluetooth Data Logger

Primary BX6-BT features and benefits:

  • Simultaneous zeroing of all channels can be triggered via a digital input (tare)
  • Measurable temperature in the device and the battery voltage
  • Protected against vibration by full encapsulation housing
  • Configuration and acquisition of measurement data with BlueDAQ in the mode “BT Classic” with Serial Port Profiles (SPP)
  • Integrated Bluetooth module has its own microcontroller.
  • Connected 3.7V lithium-ion battery can be charged by an integrated charging circuit.
  • Power supply via a Li-Ion battery from 3.6V – 4.2V

9840C TEDS READ WRITE INTELLIGENT INDICATOR

Interface’s new digital instrumentation 9840C indicator is a CE compliant and versatile precision instrument intended for the digital readout of strain gage sensors, which includes load cells. It is TEDS Plug and Play Ready and IEE 1451.4 Compliant. View: 9840C TEDS Read/Write Intelligent Indicator

Primary 9840C Intelligent Indicator features and benefits:

  • Reads and writes calibration data and coefficients to the load cell
  • Stores load cell information and calibration data and coefficients for use with up to 20 load cells
  • 10-point linearization
  • Adjustable calibration curve
  • Bipolar and accepts 2, 3, and 4 mV/V load cell inputs
  • Remote sense excitation (6-wire load cells)
  • Fast direct analog output with +/-10 VDC scalable analog output — 16 bit
  • Full duplex RS232C communication
  • Eight selectable digital filters
  • Front panel shunt calibration with two selectable resistors

LOWPROFILE™ LOAD CELL BASE KITS

Interface’s standard LowProfile Load Cells are offered with bases. The base is a flat surface, guaranteed to provide optimum support for the flexure. Use of the base, or a support surface with its equivalent flatness and stability, is required to ensure the exceptional performance of the LowProfile® Series. Note that the threaded hole in the base is on center, and a plug is permanently installed to seal dirt and moisture out of the space between the bottom hub of the flexure and the flat surface of the base. Read more about the basics of base kits. View: LowProfile™ Load Cell Base Kits

Primary LowProfile Load Cell Base Kits features and benefits:

  • 14 model options in both U.S. and Metric thread
  • 15 stainless steel model options
  • Bases are all heat treated
  • High strength materials, including stainless steel options
  • Available in LowProfile standard sizes for Interface load cell models 1000, 1200, 2400, 3200
  • Standard thread size is the same as the mating load cell
  • Custom base options available
  • When the base and load cell are ordered together, a plug is supplied in both the cell and the base to prevent damage or errors caused by over engagement of mating parts

TORQUE COUPLINGS PLUS NEW TECHNICAL GUIDE

Interface is excited to introduce a complete summary catalog and technical guide of our extensive line of Torque ROBA® DS Couplings. These Interface torsional rigid shaft coupling transmits drive torques up to the nominal torque completely backlash-free and with permanently high torsional spring rigidity. Problems to be found on other commercially available couplings, such as denting the disks or overcoming the frictional locking, are not an issue when using our couplings. The specified shaft misalignments can be 100% utilized without affecting the transmittable torque. This guarantees unlimited use. View: Torque Couplings Technical Guide and Summary Catalog for all sizes, technical details, and installation instructions.

Primary Torque Couplings options and features:

  • Non-sensitive to alternating loads of up to 100% of the nominal torque
  • Low mass inertia due to high performance density
  • Completely backlash-free up to nominal torque
  • High misalignment compensation capability at low restoring forces
  • High torsional rigidity up to nominal torque
  • Completely wear and maintenance-free
  • Optimum construction shape due to large variant range

There are two main categories of couplings used in force measurement and the biggest difference in the two is the degree of freedom needed for the application. The categories are single-jointed and double-jointed. Read more in our Couplings 101 Series.

INF4-POWERLINK TWO, THREE, AND FOUR SENSOR WEIGHT TRANSMITTER AND INDICATOR

Expanding our INF4 series, we introduced the Interface INF4-POWERLINK Two, Three, and Four Sensor Weight Transmitter and Indicator. It has a six-digit red LED display (8 mm height), space saving compact design, four buttons for the system calibration. You can store up to 50 events, use multiple load cells in parallel and set alerts for value deviations. View: INF4-POWERLINK Two, Three, and Four Sensor Weight Transmitter and Indicator

Primary INF4-POWERLINK 2, 3 and 4 features and benefits:

  • Four independent channels for monitoring and direct management of individual load cells
  • Digital equalization
  • Four channel load distribution signaling with archive
  • Automatic diagnostics comparing recorded values plus alerts
  • Event log archives for calibrations, zero settings, errors, and equalizations
  • Excitation remote sense
  • 16 load cells in parallel
  • Tare weight zero setting, semi-automatic tare (net/gross weight) and predetermined tare
  • Connections to PLC via analog output or fieldbus and PC/PLC via RS485 up to 99 instruments with line repeaters, up to 32 without line repeaters
  • Direct connection between RS485 and RS232 without converter

INF1-POWERLINK SINGLE SENSOR WEIGHT TRANSMITTER AND INDICATOR

The INF1 series added the INF1-POWERLINK Single Sensor Weight Transmitter and Indicator. Like the version above, the options for this include a compact design, use with multiple load cells (up to 8) in parallel. View: INF1-POWERLINK Single Sensor Weight Transmitter and Indicator

Primary INF1-POWERLINK Single features and benefits:

  • Connection to PLC via analog output or fieldbus
  • PC/PLC via RS485 up to 99 instruments with line repeaters, up to 32 without line repeaters
  • Remote display via RS485
  • Excitation remote sense
  • Eight load cells in parallel
  • Digital filter to reduce the effects of weight oscillation
  • Theoretical calibration and real calibration with the possibility of weight linearization up to five points
  • Tare weight zero setting and automatic zero setting at power on

SPECIAL EVENT ALERT!

We are hosting Testing Lab Essentials: Today + Tomorrow on Thursday, April 6. We are diving into products and solutions used in all types of testing labs, along with tips and best practices for modernizing your test lab. Join the conversation.  All Interface webinars are recorded if you are not able to attend the live event.

ADDITIONAL PRODUCT RESOURCES

Interface is ready to help you get the exact product based on your unique requirements.  For engineered to order or custom solution options, please contact our experienced applications experts.

Faces of Interface Featuring Garland Hawkins

Faces of Interface is an important series because it highlights the talented team members that keep Interface going strong. In this new ForceLeaders feature, we interviewed Garland Hawkins, our production planner for Interface’s most popular LowProfile load cells.  A key member of our operations and Navigators teams at Interface, this feature highlights Garland’s professional history and a few of the things he’s working on today.

Growing up in the home of a mechanical engineer, you are bound to develop a kinship with the engineering and manufacturing world. For Garland Hawkins, he remembers fondly the time spent with his father building and tinkering with different mechanical objects. While a career in the manufacturing industry wasn’t necessarily planned, he’s thrilled that it’s where his career has taken him.

Garland’s path to the manufacturing industry is a little different than his father’s trek. After high school, Garland’s career began in the logistics industry as an order filler for Lineage Logistics. He enjoyed the work and quickly showed off his talents rising through the ranks over six years from order filler to trainer and eventually the supervisor. After leaving Lineage, Garland continued his career in logistics as the shipping and receiving manager for S&G.

After two years at S&G, Garland was ready for a change of scenery. He had spent his whole life in California and wanted something new. In 2016, Garland moved to Arizona because he preferred the desert landscape and knew that growth opportunities in Arizona were on the rise. Garland began working at the airport for a consolidation company, but he knew it was just a temporary gig before getting back into the field he knew and loved of logistics.

Then an opportunity came about with Interface. Garland began with Interface in the shipping and receiving department. As he became acclimated and comfortable in this new role in the engineering and manufacturing industry, he caught his stride. Shortly after, Garland was recognized for his hard work with a promotion into the planning department and eventually into his current role as Production Planner for Interface’s LowProfile Load Cell line.

In this role, Garland is tasked with managing the supply chain and planning. Basically, everything related to shipping and logistics for LowProfile Load Cell products. This includes, monitoring parts, maintaining inventory, addressing works orders with the production floor, scheduling machine shop and production orders and aligning capacity with customer demands and requirements.

Garland notes what he loves about Interface is the opportunity for success within the company. Most importantly, Interface is hyper-focused on growing into new markets and new regions and Garland knows that this will translate to career growth and opportunities to contribute to the company’s growth.

In addition to taking advantage of opportunities to grow at Interface, Garland is also working on his own to grow his skillset and knowledge during his time at Interface. Garland recently completed his degree in Operation Management and Analysis at Ashford University.

Garland’s drive and hunger are certainly not lost on Interface either. The company recognized this ambition and nominated Garland into its prestigious cross-functional Navigators program, which is designed to take rising stars and put them through development activities that expose them to every department of the company. This working team is essential in providing ideas and plans to drive positive change with critical thinking and problem-solving throughout the company. Garland is thankful for this opportunity because it provides the ability to see the company from every angle. It is helping him better understand the impact and importance of his own role while giving him insight on growth opportunities within the company.

While he’s not working at Interface, Garland likes to relax by enjoying his relatively new hometown of Phoenix, Arizona. He’s recently taken interests in hiking and exploring the outdoors in the desert. He’s also a big sports fan, especially basketball. He enjoys playing and watching NBA games while checking out the local food scene. However, he has not adopted the Suns as his home team yet, he’s a loyal Lakers fan through and through.

We’re thrilled to have the opportunity to shed some light on one of our committed team members. Garland Hawkins is star in the making with plenty to offer and a drive to take action.