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Load Cell Basics Webinar Recap

Interface applications and load cell expert Keith Skidmore was the featured presenter at the latest ForceLeaders Forum hosted event, Load Cell Basics. In his comprehensive presentation, he highlights key subjects including fundamentals of load cell design, sensor specifications, use cases, troubleshooting and valuable performance related topics.

The entire event is now available on the Interface YouTube channel.

In this 60-minute virtual event, Keith highlights commonly asked questions from both new load cell users as well as for advanced engineers and force measurement pros.

What will you learn watching the online Load Cells Basics event?

  • Load cell designs and how they work
  • Capacities, models and how to choose the right load cell
  • Factors that can impact sensor accuracy
  • Performance, moment compensation, creep, and eccentric load sensitivity
  • Calibration and troubleshooting
  • Use Cases and FAQs

The team concluded the event by answering a series of questions from the participants. They addressed advanced technical and set-up questions, as well as frequently asked inquiries about common troubleshooting issues.

Here is a sample of questions that you can find answered in the Load Cell Basics recorded event:

  • Is the temperature compensation achieved using dummy gauges?
  • Does Interface offer or have their own software to read the TEDs?
  • Can we assume that all load cells are intrinsically safe for hazardous locations?
  • What is the IP protection rating for the electrical connection?
  • What is better way to tare load cells, by electronics or mechanical preload?
  • Which is the frequency measurement limit and how fast does the load cell respond?
  • What are recommended amplifier instrumentation brands?
  • What is the most frequent problem when installing a load cell?
  • Does the cables and amplifiers affect the results of the load cell calibration?
  • For an application to 10 kN (2250 lbf), is it too much to use a 2000 lb load cell or should we use the next higher capacity?
  • What is the maximum sampling frequency for strain gage load cells?

WATCH THE EVENT AND Q&A HERE: https://youtu.be/_oHvfAzHMig

If you have additional technical questions or would like to talk about your specific application requirements, contact our Interface Application Engineers here. 

Additional resources for troubleshooting can be found here.

Our Interface Load Cell Field Guide is also helpful for troubleshooting and advanced technical support references.  You can order here.

Dimensions of Multi-Axis Sensors Virtual Event Recap

The Interface ForceLeaders hosted forums are designed to answer frequently asked questions from testing engineers and product designers about new technologies and uses cases. In our recent virtual event, Dimensions of Multi-Axis Sensors, we discussed the considerations for these types of sensors, the test and measurement benefits, products Interface offers and various applications.

Interface recognizes that there are growing demands for multi-axis sensors.  In our hosted event, Interface’s Brian Peters kicked-off the conversation by highlighting benefits and reasoning for the use of these types of sensors, including answering some common questions. We’ve provided a recap of the event below or you can watch the event here https://youtu.be/zua1lvTh488.

What is Unique about Multi-Axis Sensors?

Multi-axis sensors have additional bridges to provide output signals for varying axes or types of mechanical loading. They are designed to measure a multitude of forces and moments simultaneously with a single load cell sensor. Fundamentally similar to other force and torque sensors with strain gage bridges bonded to machined “flexures,” each bridge typically defines a measurement axis. 

There are multiple configurations of 2, 3, or 6-axis options.

  • Axial + Torque
  • Axial + Shear
  • Axial + Moment
  • All 6 degrees of freedom

Should You Use Multi-Axis Sensors?

The largest factor to consider is the accuracy of your test model. In many test applications using standard load cells we often notice side or eccentric load, which can skew your data. While many Interface load cells, particularly mini load cells, have been designed to reject indirect loads, nothing can handle side and eccentric loads quite like a multi-axis sensor. Dedicated multi-axis designs are typically more balanced axis capacity limits with discrete signal outputs. Composite signal outputs are common in 6-axis models.

What are the Benefits of Multi-Axis Sensor Technology?

There are a number of benefits to using multi-axis sensors in addition to accounting for and accurately measuring or rejecting side and eccentric load. These benefits include:

  • Consolidate measurement signals, conserve test space
  • Measure unwanted system crosstalk
  • Quantify reaction loads through test article on “non-measure” side 
  • More successful fatigue testing through setup and load verification
  • More data, more understanding, more complete picture

What Considerations Should Engineer Make When Using Multi-Axis Sensors?

If you’ve made the decision to utilize a multi-axis sensor in your test model, please note the following considerations:

  • System-level loads and geometry
  • Maximum loading conditions
  • Chosen capacity is adequate for measurement loads as well as potential peak or extraneous loads
  • Choosing the right sensor based on primary axis measurements

Interface Multi-Axis Sensor Products

Ken Bishop details various types of multi-axis sensor technology from Interface during the highlighted ForceLeaders event you can watch here.  Interface offers a wide range of multi-axis sensors, including 3-axis, 6-axis, axial torsion and 2-axis versions. The product options give you the ability to measure forces simultaneously in three mutually perpendicular axes, with the 6-axis load cells also measuring torque around those axes.

AXIAL TORSION LOAD CELLS

Interface’s axial torsion load cell is used for measuring both torque and force in a single sensor. Typical applications of its axial torsion transducer include bearing test and material test machines. The features of our axial torsion load cell include minimal cross talk, extraneous load resistance, and the load cell is fatigue rated. Customers can also add the following options: an integral cable, compression overload protection, and connector protectors.

2-AXIS LOAD CELLS

The Interface 2-Axis load cells can measure in two directions, X and Y simultaneously. It is commonly used in applications where dual-axis measurement is important in design and testing. They are effective for applications that measure lateral forces and the narrow design fits into compact areas.

2-Axis Interface Products:

3-AXIS LOAD CELLS

Interface’s 3-axis load cell measures force simultaneously in three mutually perpendicular axes: X, Y, and Z – tension and compression. Each axis provides a unique mV/V output and requires no mathematical manipulation. The 3-axis load cell is built to minimize eccentric loading effects and crosstalk between axes. We offer five different models in its 3A Series 3-axis load cell designed for a wide variety of capacities. They are compact in size, provide 3 full bridge mV/V outputs with an IP68 option.

3-Axis Products:

6-AXIS LOAD CELLS

Interface’s 6-Axis Load Cell measures force simultaneously in three mutually perpendicular axes and three simultaneous torques about those same axes. Six full bridges provide mV/V output on six independent channels. A 36-term coefficient matrix is included for calculating the load and torque values in each axis. An 8-channel amplifier with a USB PC interface is also available which simplifies data analysis. The company offers five different models of 6-axis load cells for a wide variety of capacities. In the end, they provide more data, accuracy, are very stiff and cost-effective for a wide range of testing options.

6-Axis Products:

Keith Skidmore, an application expert at Interface, outlined a number of use cases spanning across multiple industries. They included testing programs using multi-axis sensors in automotive, medical, aerospace and defense, consumer packaging and more. Some of the application notes discussed during this recorded event include:

  • Wind tunnel testing
  • Aerospace structural and fatigue testing
  • Computer model validation
  • Friction testing
  • Medical device: ball socket testing
  • Prosthetics
  • Robotic arm
  • Hydrofoil
  • Seat testing
  • Center of gravity

Be sure to watch the YouTube video below to gain insight into some of the most frequently asked questions about multi-axis sensors.

We had a great time introducing our audience to the possibilities of Interface Multi-Axis Sensors. If you are interested in watching the video on demand of the webinar, you can click on the link below to watch the presentation in its entirety.

Envisioning the Future of Force Measurement

It is estimated that the force measurement sensor industry market, which includes strain gages and load cells, is valued at $2 billion annually. This is a result of the diverse amount of application uses for these types of sensors, whether embedded into an OEM product or for use in test and measurement. With innovations pushing product designers, this segment of the overall sensor market is growing rapidly from the advancements in robotics, semiconductors, automotive, aerospace and defense.

In these areas of growth, Interface continues to focus on the manufacturing and sales of precision force measurement products. For 52 years, Interface remains the leader in accuracy and quality. There are no plans to change that focus. What is changing is the market place and opportunities for using precision sensor technology of all sizes and capacities, whether that be for electronic vehicle testing or industrial automation, launching spacecraft or introducing new robots.

The way we develop force measurement products is continually evolving. It is our responsibility to understand trends in the engineering, testing and manufacturing, as well as identifying customer needs, in order to develop new force measurement innovations for today and into the future.

Technology is moving at a fast pace, and it’s imperative that companies like us rise to meet the demand for new innovations to solve modern and future design and testing challenges. In last week’s blog, we detailed our product development process and our evolution over the years to meet these demands. Product development has grown from a process to something that we engage in every day, especially in the customization of our standard products as well as introduction of new solutions.

The voice of our customer is instrumental in defining this development journey. We learn about new trends and opportunities for expanding our product line by listening to our customers and team members. At Interface, we know that in order to continue building upon our half-century legacy, it’s critical to keep an open mind to new solutions and continually learn how our customer’s industries are evolving too.

Interface recently had the opportunity to contribute article to two different publications that outlined our thoughts on the trends in force measurement. We were able to lean on our entire team to discover what they believe is the future of our industry. It was not only a fun exercise to take a step back and look into the future, but it was also encouraging because we realized that many of these trends are things that Interface has placed a heavy focus on in our strategic plans for the months and years to come.

Included below are links and a quick synopsis of recent articles by Interface ForceLeadersthat were published in Machine Design Magazine and Metrology News.

Machine Design Magazine: 2020 Trends in Force Measurement Sensors

Until about 10 years ago, the force test and measurement industry had been fairly unimaginative. It had developed a standard way of building analog load cells, torque transducers and other devices, and it worked for many years. However, as most of the rest of the technological world advanced and big data changed the way engineers and manufacturers work, this age-old force measurement analog technology stood out with no way to improve data collection or make it more efficient.

The digital revolution has pushed load cell manufacturers to look around and think about how customers develop products and how factories and production lines operate. Here are some of the trends force-measurement companies must get in line with or risk disappearing, as defined by Keith Skidmore, Regional Sales Director at Interface. Click here to read more

Metrology News: The Future of Force Measurement

The rise of the Internet-of-Things (IoT) and “Big Data” has had a tremendous impact on almost every industry, including force measurement. Up until about ten years ago, the industry had remained steady and predictable. There was a standard way of building load cells using analog technology that was widely accepted, and they served their purpose well. In this article Ted Larson, VP Product Management and Marketing at Interface explains the industries recent transition and what lays ahead. Read more here.

Interface will continue to remain future-focused in an effort to serve our clients force measurement needs for now and beyond. If you are interested in learning more about custom solutions or new applications, contact us here.

Faces of Interface Featuring Keith Skidmore

The combination of technical expertise and interpersonal skills is rare in an engineer. Fortunately, these are the outstanding qualities that Regional Sales Director Keith Skidmore brings to the table. Or as we like to call it at Interface, the lab.

Growing up in Cleveland, Ohio, with a dad that worked as a technical salesman, Keith experienced the impressive capabilities of science and technology first-hand, simultaneously learning how to create relationships with customers and sell solutions. Keith also had a passion for finding out how things work at a young age.  As a kid, he was always tinkering with different hardware to figure out how it worked or how to make it better.

This upbringing led Keith to The Ohio State University, where he graduated with a Bachelor of Science in mechanical engineering in 1994. His short professional career in Ohio took him to Sensotec, where he was a Technical Sales Engineer for one year. At this point, Keith’s more than 20 years in the cold, snow and rain were taking its toll. He was ready for a warmer climate.

In 1995, after visiting a friend in the Phoenix area, Keith made the decision to move out West for good. He started his career in Arizona at DH Instruments, a Fluke Company, as a Regional Sales Manager. During his time with the company, he sold pressure calibration equipment. After one year, he started to investigate career opportunities at Interface because he was interested in the mechanical applications of the company’s load cell and sensor technology products.

In October 1996, Keith joined Interface as a senior application engineer. At the time, he became one of the only application engineers on staff and had the opportunity to work in a wide variety of industries across the world. Some of Keith’s customers at the time included Lockheed Martin, Boeing, Airbus, Ford, as well as a lot of smaller companies and labs. He enjoyed working across different industries providing performance load cells and instrumentation because he was able to see all of the unique and innovative ways these companies were developing products with the use of the world’s leading force measurement equipment.

“A lot of the products that Interface makes have an impact on our daily lives. From medical technology to automotive, I enjoy seeing and learning about all the different ways our products are used to test different equipment. Having a genuine interest in the products I’m selling certainly makes it a lot easier to get our customers excited about them.” Keith Skidmore, Regional Sales Director

In 2006, he was promoted to Product Sales Manager at Interface. In this role, Keith became responsible for more product lines and gained more responsibilities, leading sales in Interface’s Specialty Products, including torque transducers, multi-axis sensors, and instrumentation. In fact, Keith recently shared his insights on the growing trends in multi-axis sensors for test and measurement projects. You can read the post here.

Skidmore remained with Interface for 10 years before moving on to take a measurement application engineer position with Measurement Solutions, a representative firm of Interface solutions based in Arizona. Measurement Solutions had been an outside sales representative firm with Interface’s for many years and continues to carry Interface’s line today. Keith experienced what it was like working as a sales representative for his former company and other OEM’s of testing products in the industry. This role provided Keith with a new perspective and helped him grow in his career as a technical salesman. After three years with Measurement Solutions, Keith returned to Interface to take on his current role as the Regional Sales Director work in representatives in Arizona, New Mexico, Kentucky, Indiana, West Virginia, New York, Michigan, Western Pennsylvania and the state where he grew up, Ohio.

He rejoined Interface because he still loves the ability to consult with customers and his outside sales force team on a diverse selection of industries and projects.

In his free time, Keith and his wife can be found mountain biking or taking trips to Flagstaff with their small dog.  He likes to get back to the green scenery and even the snow he grew up with when he lived in Ohio. In reality, he misses it just enough for a day or weekend trip. The heat and sun have won him over.

To learn more about the talented people behind Interface’s industry-leading torque and force measurement products, follow our Faces of Interface series on our blog at /blog/.

Multi-Axis Sensor Applications

For more than 50 years, Interface has proven itself as the premier provider of load cells, with the most accurate and reliable products on the market. As the technical landscape has evolved, we have invested heavily in new technology to suit the growing needs of our customers. One of the most important innovations we’ve brought to market over the past few years is our lineup of wide-ranging multi-axis sensors.

Interface Multi-Axis Sensors are designed to measure a multitude of forces and moments simultaneously with a single load cell sensor. These sensors provide multiple bridges that precisely measure the applied force from one direction with minimal crosstalk from the other axes.

Multi Axis Sensor 3AXX 3 Axis Load Cells -

Interface Multi-Axis Sensor 3-Axis Load Cell

Interface offers 3-axis, 6-axis, and axial torsion load cells, which provide the ultimate in force and torque measurement. We can measure forces simultaneously in three mutually perpendicular axes, with the 6-axis load cells also measuring torque around those axes. In addition, we offer multiple data acquisition and amplifier systems which make graphing, logging and displaying data easy enough for any experience level.

Our customers work in a wide variety of industries, and we are continually seeing new applications of our range of multi-axis sensors. These sensors are used in aerospace, automotive, medical and more.

The following application examples provide a clearer picture of the benefit of this force measurement and sensor technology.

Rocket Structural Testing – In rocket and aerospace testing, there are a million different considerations to ensure a proper launch. One of the vital force tests that need to be conducted is on the connection between the rocket and the launch vehicle. There are force and moment in multiple directions at the connection point. Interface Multi-Axis Sensors can be used to test not only the strength of the connection but also ensure a safe disconnection between the rocket and launch vehicle.

Drone Testing – One of the most interesting applications of our multi-axis sensors is in the drone industry and in areas of urban mobility. Our sensors are used to test the drone’s rotor. The drone will always pull on the sensor to create the most significant force; however, there is also a slight amount of moment that needs to be accounted for. We were able to calibrate a semi-custom load cell to account for both the large pull force and the small moment force to provide the most accurate data possible.

Prosthetics – Another impressive application of our multi-axis sensor technology is in the medical industry. We helped to test the multiple force and torque data necessary to build a strong and reliable prosthetic knee joint and spine. Each of these prosthetics has multiple motions on many axes. To measure the quality of the prosthetic and to ensure it doesn’t fail when implanted in a patient, medical OEM’s need to be able to collect data on each of these axes simultaneously.

The need for measurements on multiple axes has grown over the last couple of years because of the desire to use big data to create better products. Interface Multi-Axis Sensors provide the accurate measurements our customers need and the ability to collect those measurements simultaneously, which has created a significant boost in efficiency.

To learn more about Interface’s expanding lineup of multi-axis sensors and data acquisition systems, please contact our team of experienced Application Engineers or visit /product-category/multi-axis-sensors/.

Contributor: Keith Skidmore, Regional Sales Director at Interface

Multi-Axis-Brochure

Torque Frequently Asked Questions

Torque is an incredibly important factor to understand and measure when designing products in the automotive, aerospace and defense, industrial, and even the medical sector in some cases. In order to arm our customers with critical information on torque and torque measurement, we created a Q&A of frequently asked questions from our resident experts and contributor to this post, Keith Skidmore.

How can you tell the direction of rotation from the output voltage?

The output of a torque sensor is most often bi-polar, which means the output reverses polarity as you cross through zero in your measurement. This has nothing to do with the direction of rotation, it only affects the direction of the torque. You cannot tell the direction using the voltage; however, in many cases, torque sensors can have an encoder installed in them in order to assess the direction of rotation.

What contributes to uncertainty for a torque calibration?

Often it is the actual application of the torque. When you are testing and doing comparison calibration, there are a lot of factors that can affect the results. You might think you are controlling for variances, but subtle differences can affect results.

How do you address unknown issues such as “start-up torque” and unknown torque transient spikes?

In general, start-up torque can be minimized by using a “soft start” on a motor and controlling the startup process. If there is a lot of inertia involved, you must be careful as starting up or powering down quickly can damage the torque sensor. Transient spikes would be factors that arise during testing such as compressor cycling or pulses from an engine.

It is most important to remember that torque sensor capacity should be selected so everything falls within a capacity range, and which sometimes means making an educated guess. Torque sensors always have a safe overload range. The overload range should be reserved only for accidental use. In addition, torque sensors have limits on how high they can go in terms of measurement, and that might be a lot less than their safe overload range.

You must size the sensor to measure appropriately. You can make estimates using horsepower, rpm, and some other factors to calculate torque to come up with an average and then you can factor in spikes. Just remember that starting conditions and spikes can be up to 10x running torque, so it’s very important to consider these.

When designing a rotary torque transducer into an application, do you think the pedestal-mount or the general-purpose floating rotary torque transducer is the best approach?

Generally, we would recommend floating-mount installations. The sensor should always be protected by appropriate couplings. On a floating installation, there should be single-flex couplings on each end of the sensor, and on pedestal or foot-mount, there should be double flex couplings at each end. The sensor is never intended to be used as a bearing block. In some applications, such as high rpm or when test setups need to be changed often, a pedestal-mount will make more sense. Additional design elements and considerations must be factored in.

How do you minimize slippage at the mating surfaces for torque cells that measure in both directions?

This is an issue that is not always considered but can be a big deal. It can affect the measurement and damage the hardware. There are really two considerations. First is the effect on measurement and second is damage to the mating surfaces, and they both need to be considered.

Ultimately, it depends on the types of couplings used and the types of sensors. For example, in flange connections, it’s not the bolts themselves that prevent slippage, but the friction between the mating surfaces. Surfaces must be clean and dry, and hardware torqued to spec.

Are there sensors available that can measure both applied load and torque simultaneously?

Yes. Interface calls these types of sensors axial torsion. In most cases they are static or reaction type torque sensors. Typically, they do not rotate or only rotate within a limited range.

Is there any reason to use a load cell over a torque transducer to measure torque?

Yes, there are several reasons. The main one is that a load cell is often less expensive. In some cases, you can get better accuracy (or the same) with a load cell. The downside is mounting considerations. Measuring torque using a load cell can be easy in some cases or in some cases prove difficult or impossible. Some applications will require a torque sensor for accurate measurement.

Is there any protection in case the test torque goes over the expected capacity?

Certain torque sensors have protections built-in, and that would be a mechanical stop that protects them. Those are typically lower capacity reaction style sensors.

Have additional questions regarding torque?

The Interface team is always here to help with all your torque needs! And to end 2019, Interface is offering a special discount to all our valued customers. We are offering a 10% discount on Interface Rotary Torque Transducers and Reaction Torque Transducers. We have multiple models and capacities in stock and ready to ship now. Contact our Application Engineers today and mention the promo code TORQUE2019.

*Please note that Interface’s AxialTQ Rotary Torque is not part of this promotion. Orders must be placed by December 31, 2019. 

CONTRIBUTOR:  Keith Skidmore, Regional Sales Director

Torque Brochure