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Advancements in Instrumentation

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Listen and watch as we explore innovative new instrumentation solutions that are designed for all types of force measurement applications. We detail options for load cells, torque transducers and multi-axis sensors. Keith Skidmore and Ken Bishop highlight system-ready instrumentation options, along with features and benefits, types of software, trends and tips. What pairs best with each type of measurement device? Our experts will answer your questions in this recorded ForceLeaders event.

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Load Cell Basics Technical Q&A Part Two

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Interface hosted a series of ForceLeaders webinars this past year covering topics that included multi-axis sensors, instrumentation, torque transducers, custom solutions and more.  We plan to continue this popular series into the new year, based on the feedback we have received about topics of interest and support requirements.

One of the features that we like to include in our events is answering a list of top questions, as well as questions we get from the participants.  In our event, Load Cell Basics, we covered a lot of interesting inquiries as well as the top questions we get about our precision load cell products.

We highlighted the first group of questions in our recent post, Load Cell Basics Technical Q&A Part One. And there is more, below highlights additional questions we addressed during the live event.   A recap of the webinar is also online, reviewing key topics we discussed during the one-hour learning event with force measurement experts Keith Skidmore and Brian Peters.

Is There a Better Way to Tare a Load Cell?

Tare is defined as a deduction from the gross weight of a substance and its container made in allowance for the weight of the container, which is sometimes also called the vessel.  For purposes of this reference, we are noting the container is the actual body of the load cell.

Whether you tare a load cell by electronics or mechanical, preload taring of the system is typically done through instrumentation.  You want to ensure that whatever mechanical tare load you have on the sensor isn’t going to impede on your usable capacity range. As far as the load cell is concerned, there really is no need to accommodate any sort of mechanical tare. These are linear devices if you stay within the range.  On the mechanical preload side, it is important how you preload some of attachments especially for the LowProfile load cells. We recommend to preload if you can. It is what we do for best results so that the load path doesn’t change through the threads, which can affect very small amounts of linearity hysteresis

Does Frequency Measurement Limit Impact How Fast the Load Cell Responds?

This is a function of the mechanical flexure design for that sensor. It is important to note that each sensor is a mechanical spring. Depending on the stiffness or the deflection characteristics of a load cell, you will have different natural frequency characteristics. This information is typically documented on our product data sheets by model and configuration.  Generally, the stiffer the sensor the better it’s going to perform in cyclic applications.

Adding to this, Keith notes that load cells are great at hundreds of hertz. If you are asking about tens of thousands of hertz, they are not. There is a spot where very high frequencies of these standard load cells aren’t as effective. Most of our typical testing customers who are applying cyclical loads to a test specimen will confirm that low profile or strain gage-based load cells are great for their frequency requirements.  Work with our application engineers if you have a frequency requirement that is extremely high.

Tare and Working Up an Error Budget

This question comes in from an engineer that is working up a calculated error budget that has a mechanical tare load on that system already. Before you start your test, if you tare it how does that factor into your initial preload in the system? Will it impact your error budget? The answer is that yes, it can have some impact. You can zero out your temperature effect on zero; however, if you have a lot of preloads, you can’t. You must go back to zero to zero it out. This can impact your error budget. Basically, if you zero out, it eliminates the temperature effect. You cannot make the same assumption in your budget if you have considerable preloads.

Does Interface Recommend Particular Amplifier Instrumentation Products?

We do have a wide variety of amplifier solutions. They range from small embeddable amplifiers up to inline options that are DIN rail mounted.  We also have various digital output instrumentation productions available for ethernet, ether cat, Modbus, and USB.

It is important in your consideration to understand that there are errors that can impact instrumentation performance. Selecting the right instrumentation should be a function of the application and what are the changes in testing environment. Resolution is critical in your decision if you are doing a digital type conversion. There’s a lot of parameters to consider. Our recommendation would be to look at what is available from Interface and contact our application engineers to review your specific requirements.

What is the Most Frequent Problem When Installing a Load Cell?

One of the issues are asked about is usually related to the mechanical installation. It’s not as simple as just a nut, bolt, and threaded connection. There is a lot more to it and it’s often and discounted how important it is to ensure things are aligned properly so that you don’t have any parallel load paths. All the load must go through the load cell to make a proper measurement. For example, if you have a mounting plate and the plates are riding on the heads of the screws of the load cell, it is going to shunt the load. Mechanical installation is often missed in the test set-up design. It is often not given enough weight in importance of your test.

We also often see that users have either inadequate torque in an assembly or perhaps too much torque for the lower capacity load cells.  It’s advised to be careful of the installation torque. We recommend that if you aren’t familiar with mechanical installation, ask us for our detailed installation instructions. We provide guidance in terms of recommended torque values and proper methods of where to attach the sensor. It’s easy to over torque a load cell, as they are designed to see axial loads. We have seen users people crank on things and transmitting too much torsional load through creating performance issues that might not show up right away.

Do Cables and Amplifiers Affect Results of Load Cell Calibration?

The answer is absolutely it can impact your results. It doesn’t mean it will, but it can affect performance and measurement accuracy. For example, if you change the cable length or have an instrument that is a different temperature with cable running out of an oven into cooler temperature room, these things can influence the measurement. Even if the load cell is at a constant temperature but the cable is changing temperature, it will cause a signal to change. That’s not something you want in your measurement.

You may mitigate temperature by shielding the cable or you could have a fatter cable which could have less of an effect. Some of these things can be calibrated out. If you add a long cable and then apply loads to your load cell, it considers that there is a longer cable, and you can completely calibrate out the effect of the cable length on the signal dropping due to the resistance. Some instruments use sense to measure the voltage at the load cell. In that case, it is insensitive to any cable effect. You can change cable lengths and it doesn’t make any difference.

Is a 10kn (2,250) lb. Force Application Too Much for a 2,000 lb. Load Cell?

Yes, it’s above the calibrated range and thus you can’t guarantee performance. Load cells will typically stay linear over capacity but there’s no guarantee on the accuracy. This is especially true if you overload with frequency. You’re starting to exercise the load cell in areas where we’d recommend you stay away from to keep the results accurate. Oftentimes, you’re better off going with a larger sensor. Pay attention to the actual output. That’s one advantage of most of our products, especially in the LowProfile range.

Is There Maximum Sampling Frequency for Strain Gage Load Cells?

It is going to depend somewhat on the model of the load cell. Hundreds of hundreds of hertz are certainly adequate. If you start getting close to the natural frequency posted on our product data sheet, we recommend you review the application with our application engineers.

We know engineers who use load cells for safety impact testing. For example, you might need to sample 10 kilohertz. The load cell doesn’t make a difference for how fast you sample the signal, but those cells can only respond in typically a millisecond response time. There are no moving parts or active circuitry; however, typically testing is going to test something until it fails. It is suggested to sample it at a couple thousand hertz to make sure you capture that exact point where the system fails or spikes. If you do have some concern over creep error that’s introduced, record what that non-zero value is as soon as you release that load. That is an accurate measurement of how much creep error was introduced being symmetric.

We exercise our load cells before calibration. It’s relatively quick and typically done in hydraulic frames which are automated to test where they cycle the load in short cycle intervals, like 30 seconds. It’s really the magnitude of the exercising, not how long it lasts. If load is being tested at 120% for an hour, that’s no better than 10 seconds, other than it introduced a lot of creep for an hour. Exercising means you must wait longer for the creep to return, so if the load is a fast cycle, you can check the zero quickly.

If you have additional questions for our experts, we recommend that you visit our technical support resources. We have commonly asked questions, installation guides and manuals and more.  We are also here to support you. Contact our technical support team if you need assistance.

Additional Resources

 

Load Cell Field Guide

Load Cell Basics Sensor Specifications

Load Cell Basics Technical Q&A Part One

Interface 1200 Precision LowProfile Load Cell Series Product Highlight

Insights in Torque Testing Featured in Quality Magazine

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With the explosive growth in industrial automation and advanced manufacturing, torque measurement is a hot topic for test and measurement applications across a multitude of industries. We see demand rising due to the use in electric and autonomous vehicle testing, as well as in building components used in robotics and for spacecraft. Demand for torque transducers is so popular, Quality Magazine asked Interface’s product and custom solutions expert Keith Skidmore to contribute an article all about torque testing and how to get the most out of the transducer’s testing data.

Interface has a deep line of innovative torque transducers used where torque measurement is critical to the success of engineering and manufacturing products and components. We provide both an extensive array of standard transducers and custom torque solutions to be used in applications as large as rocket ships, to as small as measuring the torque on a bolt wrench.

Included below is a brief overview of Keith Skidmore’s contributed article in Quality Magazine outlining the basics of torque testing and providing examples of real-world applications of Interface products used to test and measure torque.

Getting The Most Out of Torque Testing

Torque is defined as the rotational equivalent of linear force. It’s a measure of how much a force acting on an object causes that object to rotate. This is one of the key measurements for engineers doing design, test, and manufacturing across a wide variety of industries where machines, vehicles, components and parts include a spinning or rotating motion. It’s critical to understand how to measure torque if you’re doing product development with these types of systems such as engines, crankshafts, gearboxes, transmissions, and rotors.

The incredibly wide variety of torque transducers, different types of devices and tests and the accompanying accessories necessary for different projects can make it difficult to determine what is needed for each individual application. For instance, torque tests are often used in the automotive industry to assess engine torque and speed, but the products used can differ between a typical gas vehicle and newly introduced electric vehicles. Torque is also frequently used to test the tightness of a variety of lug nuts and screws, which is an entirely different measurement solution.

This article provides a brief overview of the key considerations when planning for a torque test. It includes the different types of torque testing, the different torque sensor styles, accessories, mounts, and other tips and tricks. It also provides a brief overview of the potential applications of torque tests with pictures.

The article goes on to provide the basics of torque testing, as well as providing real world applications of torque test and measurement. Here is a preview of one of the applications included in Keith’s contribution to Quality Magazine. To read the article in its entirety, please click the link here.

Engine Dynamometer Testing

In this application example, a rotary torque transducer is used to measure the speed and torque of an engine. This rotary transducer can sense the torque of the engine with high precision and provide an electrical output that is converted from an analog to a digital signal. A rotary transducer is necessary due to the spinning element involved in the engine. It’s paired with a very high-quality coupling and is mounted in a fixed position. Both are necessary to account for the high speeds used in the test. This application would allow the user to measure both torque and speed of the engine simultaneously, which will provide valuable data in confirming the design of the engine or determining if it needs to be adjusted for the vehicle it will drive.

To see the range of torque products offered by Interface, download our Interface Torque Transducers brochure.

Additional Resources

New Twist on Torque Webinar

Torque Measurement for Electric Vehicles

Dental Handpiece Torque Check

OEM: Torque Verification

AxialTQ™ Wireless Rotary Torque Transducer

 

Recap of Inventive Multi-Axis and Instrumentation Webinar

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Interface’s resident solutions experts Keith Skidmore and Ken Bishop detailed a series of multi-axis products and advanced instrumentation options in our latest ForceLeaders webinar. They topics discussed during this recorded event included detailed features and benefits of the line of 3-Axis and 6-Axis Multi-Axis Sensors available from Interface. In summary, if you are looking for more data, to maximize your return on testing investments and need a compact solution compared to using multiple single load cells, multi-axis load cells may be the right solution for your application or testing project.

Pairing your sensor with right type of instrumentation that is best suited for the device and your data requirements is an important consideration.  During event, Keith shares why the BX8 Data Acquisition System and Amplifier provides 8-channel synchronized sampling and internal calculation of axis load values for 6-axis sensors. The BX8 provides high-speed synchronous sampling that is critical for dynamic measurements. It is high resolution and low noise and comes with our BlueDAQ software for data viewing and analysis. There is an option to also use BlueDAQ PRO! with MathScript. Multiple BX8 can be synchronized for use with 12-channel 6-axis sensors and force plates, which are discussed later during the event. For large capacity 6-axis sensors, you can also use two BX8’s to create a 72-coeffecient matrix. Watch the event to learn more and read about 6-Axis and BX8 powerful measurement solution.

In contrast to the BX8, Keith details the Interface BSC4 and shares important features that make it a good instrumentation choice to use with our model 3A, 3AR 3-Axis load cells. It can be used with up to four mV/V or VDC output sensors. It is a compact and convenient instrumentation option, compared to using multiple single-channel amplifiers. Our BSC4D comes with BlueDAQ software and is LabView compatible. Learn more about 3-Axis and BSC4.

You will also get the first look at our latest instrumentation solution, the BX6-BT Wireless 6-Axis Data Logger.  This new product is miniature in size, offers 7-channels with Bluetooth functionality. It logs to micro-SD card and is BlueDAQ compatible. It also does matrix math.

Further in the webinar, get the latest tips on mounting multi-axis sensors and using mounting plates and why we are seeing more use cases for Interface custom force plates. You don’t want to miss out on these important set-up instructions, frequently asked questions, and tips for ensuring you don’t compromise accuracy and reliability in your testing.

Watch the webinar and you’ll also learn about applications that use multi-axis and advanced instrumentation, including for structural testing, friction testing, seat testing and special condition calibration. We will be posting addition blogs from the learnings of this in-depth expert discussion, including top 10 FAQs, calibrating multi-axis sensors and the future of test and measurement using multi-axis load cells.

Recap of Latest Spin on AxialTQ Webinar

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Interface recently hosted a new webinar in our ForceLeaders series that highlighted the revolutionary AxialTQ product.  The event reviewed the bearingless wireless rotary torque transducer design and detailed component specifications, why test engineers prefer the AxialTQ, and use cases for this precision measurement system.

If you were not able to attend the Latest Spin on AxialTQ event, you can watch the entire recording online here.

The revolutionary AxialTQ was first introduced in 2018. The design originated from the popular HRDT product that utilized a rotor stator gap design as a single component. After hundreds of users, we started the product engineering exercise to see how we could advance the soon-to-retire HRDT and evolve it into something that would perfectly fit current market conditions.

As technologies were changing testing protocols and requirements, such as for electric motors, alternative energy hardware, space vehicles and industrial machine automation, we wanted to add new functionality. Jay Bradley and the Interface engineering team began the process by looking at DIN size optimization, shorter stators, additional coupling options, advanced software configurations and simple “drop-in” replacement parts with a modular design.

After thousands of design hours and testing, Interface released the AxialTQ. The specialized product is a unique combination of accuracy, reliability and ease of use that redefines the standard torque measurement device in terms of function and durability.

Engineers prefer the new AxialTQ because of the time-proven sensing element with longer active area providing greater measurement sensitivity while being less vulnerable to shock loads.  The high-resolution digital electronics are state-of-the art. Uniquely, the large gap design up to 6 mm axial and 12 mm radial minimizes contact damage which is important at high-speed testing. It has 120-degree partial loop antenna on the stator to make installation easier.

Specialized design features of AxialTQ make it a great fit for test and production applications.

  • Crash-proof design for maximum reliability
  • Industry-leading gap to prevent damage to rotor stator at full speed
  • Simultaneous analog and digital outputs, enables real-time control and data collection
  • Interchangeable stators and output modules minimize parts inventory
  • Versatile design and wide range of configurations to match any application
  • Hardware is self-configuring
  • New advanced software with added features and logging capabilities
  • Rotor and stator coils designed using printed circuit boards for durability

The AxialTQ rotor sensing element and electronics are the heart of the system. It has a rugged design for all types of torque measurement applications.  It comes in 8 torque capacities. The status assembly matches to the rotor DIN size and is interchangeable with equipment DIN size rotor assemblies, increasing usability.  The USB digital output module has galvanic isolation on all outputs and has standard IP65 ingress protection.  It enables real-time control and accurate data collection.

Keith Skidmore shared several use cases during the presentation, including engine dynamometers, motor test stands and other automotive production line applications.

The AxialTQ is designed for testing anything that spins. It’s ideal in testing and production of hydraulic motors, EVs, helicopters, aircraft, and drones, along with windmills and industrial fans.  It’s great for testing forklifts, off-road and utility vehicles as wells as tractors and watercraft.  AxialTQ is also generally used for measuring torque on industrial motor assemblies, pumps, appliances, braking systems, and motor vehicle accessories.

Watch the entire webinar below to hear Keith and Jay share tips, specifications, frequently asked questions and how to get the most out of your torque measurement applications.

Learn more about AxialTQ here.

Latest Spin on AxialTQ

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Our latest webinar, Latest Spin on AxialTQ features Keith Skidmore and Jay Bradley detailing all aspects of AxialTQ including design, features, performance specifications, customizable options, and applications of this revolutionary torque transducer.

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Recap of New Twist on Torque

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In our latest virtual event New Twist on Torque, Randy White and Keith Skidmore shared valuable insights and tips using this type of sensor. With more than 50 different types of torque transducers available at Interface, this webinar highlighted the differences, specifications, use cases and integration advice from our experts.

The ForceLeaders webinar started off with a quick rundown on the history of torque from the first dynamometers measuring the torque and RPMs of motors to the revolutionary Interface AxialTQ. In fact, you can now see how this rotary torque transducer is actually being used in today’s advanced engine dynamometers solution here. The conversation quickly lead to multiple design options and progressed to vital integration tips, considerations and common questions.

By definition, torque transducers convert a mechanical input of torque to an electrical output signal where the signal is directly proportional to the torque input. They consist of a metal spring element like a load cell. The strain gages are bonded to the flexure in a Wheatstone bridge configuration. As torque is applied to the sensor, bending or shear strain in the gaged area, it causes the strain gages to change resistance and generate an output voltage signal proportional to torque. You can read more about torque basics in our Torque Transducers 101 post.

Throughout the event, our experts shared important know-how in using the various types of transducers, including rotary, reaction, miniaturized and even custom-built products. Reaction sensors, also referred to as static, measure torque without rotating. A rotary sensor, also called dynamic, rotates as part of a system. It is merely a reaction sensor that’s allowed to rotate. And yes, you can customize torque transducers to fit your exact requirements. You can see all our torque products here.

Keith detailed four important considerations related to capacity: drive service factors, load service factors, stopping and starting conditions and extraneous loading. There was a robust discussion about fixed and floating mounting options and the importance of couplings. Randy highlighted all the products available and also gave a great recap of several real use cases across various several industries including energy markets, automotive and vehicles, robotics and more.

Be sure to watch the entire event for an abundance of firsthand knowledge and expertise based on working with thousands of customers using torque transducers all types of applications.

WATCH THE ENTIRE RECORDED NEW TWIST ON TORQUE EVENT

There is a lot of information packed in this online event including ten integration tips that will help you define your requirements to get the right sensor for the job. Be sure to check out the FAQs and innovative application highlights, where we showcase everything from ATV and Mountain Bike Testing to Poultry Feeders and Hydrogen Power Generation. You can see all our application notes here.

The topics discussed during this recorded event include:

  • The Evolution of Torque Measurement
  • Interface Torque Transducer Specifications and Designs
  • Useful Application Tips when Using Torque Transducers
  • Review of Couplings and Instrumentation
  • Customization and Calibration
  • Industry Use Cases
  • Frequently Asked Questions

You can watch all of our events on our Interface YouTube channel.

Additional Torque FAQs are here.

Making the Case for Custom Solutions Webinar Recap

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Interface application experts and custom solution pros, Ken Bishop and Keith Skidmore provided valuable insights in our latest virtual event as to how, when, and why, you should connect with our team for help in designing, engineering, and building custom sensor solutions.

Making the Case for Custom Solutions, an Interface ForceLeaders hosted webinar, delved into the scope of options across all types of technologies and devices used in test and measurement. The focus of the event highlighted the importance of early engagement in the design and conception process when evaluating whether you needed something beyond a standard product.

Custom Solutions go beyond engineered to order products, where you might need to change a thread adapter, connector, or mounting hole. Interface custom solution can range from single components designed for unique applications to multiple components configured as a system. Custom solutions are most frequently used for OEM products, as embedded pieces.

Interface offers fully designed load cells or load pins to meet the application requirements. Torque transducers‘ options include custom shaft sizes, outputs, temperature ranges, and other configurations to fit the application. Wireless is also a common consideration for custom solutions, giving a wider use for monitoring, reporting, and system support.

If we build it, we can customize it. This also applies to multi-axis sensors and various types of instrumentation. In the webinar, Keith and Ken dive into several systems and use cases that highlight multiple components configured to exact specifications from mobile force testing systems to monitoring bridges seismic activity with special waterproof casings.

Six Custom Solution Design and Specification Recommendations for Getting Started

  1. What do you want to measure?
  2. How will the sensor be used?
  3. Do you need multiple sensors or a single device?
  4. Is this embedded into an OEM application or solely for test and measurement?
  5. Do you have a cost target?
  6. How will you read the results?

The mechanics of getting something custom starts with the scope and determining what needs to be measured. Then our experienced engineers will design the product working with your team. Once designs are approved, the manufacturing process begins. Using our state-of-the-art machine shop world-class assembly and custom solution calibration experts, Interface confidently delivers the products that stand with our seal of quality, accuracy, and performance standards.

Here are the topics discussed in the Making the Case for Custom Solutions event.

  • What is Considered an Interface Custom Solution
  • Differences Between Engineered to Order and Custom
  • Design and Specification Recommendations
  • Customizations Options and Considerations
  • Building Systems
  • Tips for Engaging Custom Solutions Engineers
  • The World of Possibilities
  • FAQs

Watch the entire event here:

The benefits of engaging Interface Custom Solutions Engineers are that we become an extension of your engineering resources along with access to our models, drawings, and assets to help with your project success. Whether we are building solutions with our proprietary strain gages or finding Bluetooth instrumentation for read-outs on custom load cells, we work as your partner with ownership in your project’s success.  It’s what we know, it’s what we do, and we get custom solutions. We’ve been doing custom solutions for force and torque for 52 years.

When you are ready to engage our team, we stand ready to help. We’ve been building small and large volume custom solutions for innovative industry leaders in aerospace, industrial automation, automotive, agriculture, infrastructure, energy, and more.  In Making the Case for Custom Solutions, Keith and Ken Put our experts to the test and let’s explore the possibilities together.

Get started by letting us know what you have in mind.  Request a custom solution here.

Read more in our What’s New in Custom Solutions post.

Additional Events:

Use Cases for Load Pins

Load Cell Basics

 

Load Cell Basics Sensor Specifications

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When selecting a load cell, it’s critical to understand the major factors impacting sensor accuracy. These factors are determined by the materials and components used in the construction of the load cell, the calibration, instrumentation, the accessories such as cables, and mounting installation. Each must be considered in the specific use cases for the load cells.

During our virtual event, Load Cell Basics, applications expert Keith Skidmore detailed everything you need to know about load cells and how to choose the right load cell.  First, Keith highlighted four vital application considerations:

Mechanical – Dimensions and Mounting

Electrical – Output and Excitation

Environmental – Temperature and Moisture

Performance – Accuracy and Thermals

Taking a deeper dive into performance, an important consideration when selecting your load cell are the sensor specifications and how they impact accuracy. The sensor specifications relate to the max error of various parameters. The specifications are always included in product spec sheets and are expressed using the following values – %FS, %RO, %, %/°F, time-related. Specifications listed relate to the max error for accuracy and temperature.

Interface provides all sensor specification data for our load cells in the product datasheets found on each product page for easy download.

The information we provide for every load cell typically includes:

Accuracy:

  • Static Error Band
  • Non-linearity
  • Hysteresis
  • Non-repeatability
  • Creep
  • Side Load Sensitivity
  • Eccentric Load Sensitivity

Temperature:

  • Compensated Range
  • Operating Range
  • Effect on Zero
  • Effect on Span

Further definitions can be found in our online technical glossary.  Here are a few that we highlighted in the Load Cell Basics webinar.

Static Error Band: A band encompassing all points on the ascending and descending curves centered on the best fit straight line. It is expressed in units of %FS.

SEB Output: The output at capacity based on the best fit straight line.

Non-repeatability: The maximum difference between output readings for repeated loadings under IDENTICAL LOADING AND ENVIRONMENTAL CONDITIONS. In practice, there are many factors that affect repeatability that ARE NOT included in the non-repeatability specification. It is normally expressed in units of %RO.

Non-linearity: The difference in the output from a straight line. It is normally expressed in units of %FS.

Hysteresis: The difference in the ascending versus descending curves. This is normally expressed in units of %F.

Understanding these factors and the maximum error for your specific project is critical to selecting a load cell and getting the best possible data out of it.

To learn more about sensor specifications for load cells, review the product specs on each datasheet or in our product catalogs. For additional help, call to speak with our application engineers at 888-557-2533.

To view additional online events, please go to our events page.