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How Do Load Cells Work?

What is the most frequently searched question searched related to Interface and the products we manufacture? It may seem overly simple to test engineers and frequent buyers of Interface force measurement solutions, but to many it is an important question. What do inquisitive users of the internet want to know? They want to how load cells work.

Diving into this question, we learned that many understand the purpose of a load cell. A load cell converts an applied mechanical force, whether that is tension, compression, or torsion, into a measurable electrical signal. Any change in force, increases or decreases the signal output change in proportion.

There are fewer people that understand how a force transducer works. After 55 years making load cells, we thought we should help provide an answer to an incredibly good question. Here is a quick technical brief on how a load cell works.

Interface Tech Talk Answers How Do Load Cells Work

A load cell has two basic components. It has a spring element that is often known as a flexure that mechanically supports the load to be measured and a deflection measurement element that responds to flexure movement resulting from the application of force.

In simpler terms, there is a bending beam under the load and when weight or force is applied, the change in bend (deflection) results in change in output.

A load cell’s basic function is to take applied force and convert it into an output signal that provides the user with a measurement. This process of converting a force into data is typically completed through a Wheatstone bridge that is comprised of strain gages.

Strain Gage Load Cells: A strain gage is typically constructed of an exceptionally fine wire or metal foil that is arranged in a grid-like pattern. Strain gages are strategically placed on the load cell flexure and bonded securely, such that the force induced deflection of the flexure causes the gages to stretch or compress. Thus, when tension or compression is applied, the electrical resistance of the strain gages changes and the balance of the Wheatstone bridge then shifts positive or negative. Fundamentally, the strain gages convert force, pressure, or weight into a change that can then be measured as an electrical signal.

Why use strain gages in load cells? Strain gage characteristics include thermal tracking, temperature compensation, creep compensation, frequency response, and non-repeatability. The major advantage of the strain gage as the deflection measuring element is the fact that it has infinite resolution. That means that no matter how small the deflection, it can be measured as a change in the resistance of the strain gage.

The strain gage is the critical foundation of a load cell and the most vital component for accurate and reliable measurements. One thing to understand about Interface load cells is that we develop our own strain gages in-house using a proprietary manufacturing process to ensure premium performance.

In addition to strain gage load cells, there are also two different less common load cells that use a diverse types of data collection method. This is defined as pneumatic and hydraulic methods.

Pneumatic: These load cells are typically used for measuring lower weights with high degrees of accuracy. They measure weight in terms of force-balance, meaning that weight is reported as a change in pressure. Key advantages of pneumatic load cells are their resistance to electrical noise and inability to spark, in addition to their low reactivity to temperature changes.

Hydraulic: As the name suggests, these load cells utilize fluid pressure for measurement. Like pneumatic load cells, hydraulic load cells balance force by measuring weight as a change in pressure, and the pressure of the fluid rises because of an increase in force. These load cells have no electric components, allowing them to perform well in hazardous conditions.

How to choose the right load cell?

Load cells seem like an extremely basic piece of equipment used to measure different forces such as weight, compression, tension, torsion, or a combination of these. It can be on a single axis or across multiple axes. However, there are many distinct types of strain gages and load cells that are designed for a variety of environments and force measurement testing requirements.

Specifications of a measurement sensor validate the design capabilities and capacities, including the amount of measurement that can be used for a particular device before you exceed the limits.

The field of force measurement has the same types of constraints as any other discipline. It starts with considerations of weight, size, cost, accuracy, useful life, and rated capacity. This also means considerations for extraneous forces, test profile, error specifications, temperature, altitude, pressure, and environment are particularly important when choosing a load cell.

The major difference in strain gages is the base material used in the manufacturing process. Varied materials are used when a load cell needs to perform optimally in a variety of temperatures, humidity levels, and elevations. Matching the correct strain gage and a load cell to the customer’s needs is critical to accuracy. It is why Interface has excelled in building precision load cells for five and half decades and continues to be a trusted supplier to industry market leaders, innovators, engineers, and testing houses around the world. It is what we do best. It is what we know.

Our team of engineers and manufacturing experts use expertise that has built over time, applications, and load cell experience. A load cell starts as a raw piece of steel, aluminum, or other metal. It is machined, gaged, wired, finished, and calibrated by experts in load cell production, machinists, and quality engineers.

If you are just beginning to work with products that require accurate force measurement, we would suggest that you speak with an application engineer who can help you understand the load cell that will fit best for your use case.

When shopping for a load cell it is important to know the type of force that you need to measure, the size of the application, the environment in which you will be measuring the application, the accuracy of data needed, the type of communication output that will work with your current test system and if there are any unique details about your application, like extreme or hazardous conditions.

ADDITIONAL RESOURCES

Interface Load Cell Field Guide

Interface Presents Load Cell Basics

LowProfile Load Cells 101

Load Cell 101 and What You Need to Know

Technical Library

LowProfile Cutaway

Interface Best Selling Products in 2022

Interface sells tens of thousands of force measurement products every year. As a manufacturer of the world’s highest quality load cells, it is no surprise that our top selling products are the precision load cells that we engineer and build in our US headquarters.

We have been manufacturing high-accuracy load cells in all kinds of configurations and capacities for 55 years. With growing demands for complete systems, instrumentation, and specialty sensors, we continue to add new products and expand our line of standard and engineered to order offerings. In 2022, we again have grown our Interface Product Catalog significantly.

As is tradition, we want to share our best selling products and what garnered the most views by product categories and models. The criteria for what constitute a best seller can vary depending on the industry and the specific market. A best seller is typically considered to be a product that is in high demand and is selling well consistently over a period.  In general, Interface best sellers are products that have a strong record of success and are highly sought after by our customers year-over-year.

In our annual recap, we do not include products that are custom OEM, as these unique sensors are built for a particular use case.  Interface defines a best seller as a product model series that ranks among the top sellers in our entire force measurement solutions line.

2022 Interface Best Selling Products

Load Cells

Mini Load Cells

Torque Transducers

Specialty Products

Instrumentation

What captured the greatest interest in 2022 by users and researchers of force measurement solutions? We have cataloged what is capturing the greatest interest from you and your peers. The following are Interface products most frequently viewed this past year by test and measurement professionals, engineers, product designers, and manufacturers around the world.

Interface Top 10 Product Categories Ranked by Online Interest in 2022

  1. Load Cells
  2. Torque Transducers
  3. Instrumentation
  4. Tension and Compression Load Cells
  5. Accessories
  6. Mini Load Cells
  7. Multi-Axis Sensors
  8. Compression-Only Load Cells
  9. Load Button Load Cells
  10. LowProfile Load Cells

Interface Products Most Viewed Online in 2022

Summary Catalog 8 Pages

Interface and The Race to Space

Like many, we are celebrating some incredible milestones in the space industry this year. With every milestone, there is a long path of discovery, invention, and experience that creates these extraordinary moments.

The 53-year history of Interface is rich in experiences supplying force and torque measurement solutions to the engineers and innovators of space vehicles and the structures that support them. For decades Interface has supplied load cells, torque transducers, and multi-axis sensors of all sizes and capacities to the organizations that put the first man on the moon and to those that are pursuing the commercialization of space travel and colonization of other planets.

Our legacy as a reputable provider of sensor technologies has created a reliance on Interface products and expert calibration services. Our products have been and are used today in the development and flight qualification for the ascent and now descent of spacecraft, with rapid expansion and frequency. As we enter a new era of recoverable spacecraft, we are seeing more dependence on Interface as the supplier of the measurement devices used by these remarkable innovators, builders, and test engineers.

Why Interface? It comes down to reliability and accuracy, two extremely important measures of success in the launch and recovery of spacecraft.  These measures are also critical factors given the acceleration in space travel for both valuable cargo and with greater occurrences, humans.

Beyond the performance factors of precision force and torque measurement solutions that Interface engineers and manufactures, we are chosen by the steadfast leaders and new entrepreneurs in the space industries because of quality and our ability to customize our products to exact specifications.

You will find Interface products used in thrust testing, structural testing and even force gravity testing.  Every new test and launch inspire the Interface team to keep doing what we do. In fact, you can find our high-capacity and miniature load cells in use with future engineers and astronauts at universities around the world that are inventing new planetary exploration vehicles and rockets.  Learn more here.

Interface provides products that accurately measure thrust, which is critical in cargo lifting. Every test must be verifiably accurate due to the trustworthiness and safety requirements of moving the ever-increasing valuable payloads, which is beyond stellar communication technologies. It’s now about launching and returning humans, with frequency, in the new era of space travel.

Interface load cells are also commonly used in the production and development of launch structures.  These structures must withstand incredible forces during liftoff and return.

You can also find the Interface blue and stainless-steel load cells in the designs and for testing structures and aerodynamics for payloads of all types.

NASA’s Space Launch System (SLS) core stage is 27 feet in diameter and 200+ feet tall. Core components including liquid hydrogen and oxygen tanks must withstand launch loads up to 9 million pounds-force (lbf). Interface 1200 High-Capacity Standard Precision Low-Profile™ Load Cell Model 1260 for 600,000 lbf capacity, Model 1280 for 1,000,000 lbf capacity and Model 1290 for 2,000,000 lbf capacity were used in the design and testing of the structure.

Load cells were attached to hydraulic cylinders at various locations along test stands to provide precise test forces. Strain gages bonded to rocket structure surface and connected to data acquisition system for stress analysis. Read more here: /solutions/aerospace-industry/rocket-structural-testing/.

Exploring the possibilities of what you can measure?  Interface is here to support your vision and mission. Contact our experts to help you get exactly what you need to accurately measure your designs.

 

 

Making the Case for Custom Solutions Webinar Recap

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

 

Recap of Use Cases for Load Pins Webinar

Interface load pins continue to grow in demand as an easy to integrate and cost-effective sensor solution for many diverse applications as direct replacements for clevis or pivot pins. Most commonly used for lifting and rigging mechanisms in construction, structural assemblies and moving devices, load pins are typically used in rope, chain and brake anchors, sheaves, shackles, bearing blocks and pivots.

To provide greater insights and answers to questions asked to our force measurement application experts, Interface hosted a ForceLeaders Forum event, Use Cases for Load Pins. The event, now archived on our YouTube channel, highlights why more and more industries are using load pins include for projects related to infrastructure, aerospace and defense, industrial automation, manufacturing, maritime, and in energy markets such as oil and gas.

Regional Sales Director Elliot Speidell covered a series of topics in this live event, which included:

  • Who is Using Load Pins and Why?
  • Models and Design Aspects of Load Pins
  • Integration Considerations
  • Installation Factors
  • Load Pin Capabilities including Wireless Features
  • Standard and Customization Options
  • New-Found Applications Using Load Pins
  • Differences and Advantages
  • FAQs

WATCH NOW: THE ‘USE CASES FOR LOAD PINS’ ON-DEMAND EVENT

This webinar covers great detail in installation tips, integration considerations, design features and more.  Here are just a few highlights from the webinar.

Load pins measure tensile and compression forces via strain gages that are installed within a small bore through the center of the pin. Two grooves are machined into the outer circumference of the pin to define the shear planes, which are located between the forces being measured. They are made of rugged stainless-steel material and are commonly used for safety applications.  They are easy to retrofit and inherently waterproof by design, making it useful in submersible and adverse environmental conditions. Load pins have multiple bridge options and can be cabled or wireless.

One of the most important features and distinctions of a load pin is the ability to customize the design to fit the application. Due to the nature of requirements and fact most load pins are custom solutions, they often do not have any charges for NRE. Contact our application experts to learn of the possibilities and design options.

When installing a load pin various factors need to be considered which can influence the performance or accuracy. The fit of the pin within a structure is important to the overall performance of the load pin. For an optimal performance, an H7/g6 clearance would normally be recommended; however, this is not always achievable in the field and some slight loss of repeatability and linearity can normally be tolerated to achieve an “easy to fit” requirement.

Load pins are a great sensor to use in a “smart system” application for automated feedback, alarms, and real-time notifications.  They integrate with all types of instrumentation, including digital output options. Though they are simple and easy to use, they are known for hardiness. It is important to understand they are not “precision performance” devices, they are designed for standard force measurement applications that require immediate feedback. Also, they are easy to incorporate with existing actuator set-ups.

Watch the event to learn more about the questions engineers and testing experts asked us about using load pins. For specific industry examples, from bridges to crane regulation use, tune into the recorded event or visit our application notes here. Need us to get started on a custom design?  Contact us today.

Trending at Interface

As in years past, the Interface team looks at trends in what products caught the greatest interest of our customers, along with those that are top sellers throughout the year.

We’ve gathered our key findings based on searches and purchases by industry-leading engineers, product designers, testing labs, manufacturers and T&M pros using Interface solutions. Here is a summary of the trends over the past 12 months.

TRENDING PRODUCT CATEGORES IN 2020

#1 LOAD CELLS – There is no surprise that topping the 2020 list is what we are best known for, our precision load cells. When quality, accuracy, and reliability matter Interface Models 1000, 1100, 1500 and 1600 in various capacities ranked highest in interest. What’s the top seller? The 1200 Standard Precision LowProfile® Load Cell ranks number one, with the 1000 Fatigue Rated Load Cell in second place.

#2 TORQUE TRANSDUCERS – Torque is definitely trending, taking the number two spot. Hot picks are the MRT Miniature Flange Style Reaction Torque Transducer, T8, T25 and our proprietary AxialTQ. Read Torque 101 here.

#3 INSTRUMENTATION – One of the most popular adds to any purchase is instrumentation like the DMA2, SGA, 9320 or 9840.

#4 MULTI-AXIS SENSORS – Watch Dimensions of Multi-Axis Sensors to learn more about why multi-axis is trending, including the popular 3AXX 3-Axis Force Load Cell.

#5 MINIATURE LOAD CELLS – Interface’s expertise for engineering force measurement applies to a wide range of capacities and sizes, including Interface Mini best sellers: SSM and SSM2 Sealed S-Type Load Cells, SM-S Type and SMT Miniature Load Cells followed closely by MB, MBP, WMC Stainless Steel Miniature Load Cell and SMTM models.

#6 CALIBRATION SYSTEMS – These Interface systems are growing in popularity. Read why here.

#7 CALIBRATION SERVICES AND REPAIR ­­­– Our customers can depend on us for our services. Click here to request service today.

#8 DIGITAL INSTRUMENTATION – Interface has expanded our line of digital instrumentation based on growing demands. See what’s hot here, like our BX8.

#9 LOAD PINS, LOAD SHACKLES AND TENSION LINKS – A new entry to the trends list this year based on the high interest for these specialty products including the wireless options.

#10 LOAD BUTTON LOAD CELLS – Robotics, automation and testing in confined and compact spaces has raised greater interest in highly-accurate load button load cells, including our new ConvexBT and our popular LBM and LBS models.

Based on feedback and our analysis of trends, we know that getting exactly what you want is as important as the product category selection. Engineered to order, custom solutions and complete systems are rapidly growing in demand as Interface customers evaluate ways to embed sensor technologies into products or utilize advances sensor technologies, along with wireless and Bluetooth communication capabilities.

Take a look at why Interface Engineered to Order Solutions continue to be in high demand by helping our customers get exactly what they need.

Interface has played an important role in shaping the test and measurement industry and though we know our standard catalog is robust, we are always here to get the exact product for our customer’s exact requirements. How can we help you get what you want in 2021 and beyond?  Reach out and let’s start the conversation now.

Compression Force Testing 101

Compression is a type of force that we apply every day often without thinking and compression is intensely tested in many of the products we use on a daily basis.

Compression force is defined as the energy generated from compressing an object or substance. Compressive force is simply the direction of the force applied to the load cell. The compressive strength of materials and structures is an incredibly important engineering consideration in both designs and build.

Whether you are clicking the keys on your laptop at work or slamming on your brakes to avoid an accident on your morning commute, you are using the compression force. Testing of the compression force is essential in developing a reliable and sturdy product that can withstand the pressure applied to it many times over. Often, safety is at the core of compression testing.

Load cells incorporated into the testing process work by measuring the pushing force of an application on a single axis. The strain gage compresses to measure the load applied. The deformation of the strain gage provides the measurement data. Application tests measure the total compression force the products or structures can handle, as well as the effects of compression over time through stress tests. In both cases, original equipment manufacturers (OEMs) need accurate measurements to guarantee their products can withstand compression in the short and long-term.

Interface supplies a variety of compression-focused load cells and accessories for all types of applications, both for test and measurement, as well as for inclusion in originally manufactured products and solutions. These compression load cells are often used in vehicles, industrial automation, aerospace, and defense industries. Applications are wide-ranging, from testing the impact of drones dropping packages to the material strength of bridges during an earthquake. Interface load cells are highly-rated to provide the most accurate data and reliability over time, which is why engineers rely on Interface compression-only load cells.

Here are a few of the compression load cells available from Interface:

1601 Gold Standard® Calibration Compression-Only LowProfile® Load Cells – Interface’s Gold Standard® Load Cells are designed for calibrating other load cells. The 1601 load cell is compression-only and has options available for a second and third bridge and overload protection.

1201 Compression-Only Standard Precision LowProfile® Load Cells – The Interface 1201 LowProfile® load cell provides a “compression-only” force measurement. Its spherical-shaped top surface helps provide minimal off-axis loading. 1201 is our most popular load cell designed for static applications and has a higher output than most competitive load cells.

2101 Dual Range Standard Compression-Only Load Cells – The Interface Model 2101 consists of lower and higher capacity model 1200 type load cells which are stacked with overload protection built into the lower capacity load cell permitting the high resolution to be obtained at both low and high levels of capacity. The Model 1201 is LowProfile® moment compensated.

LBM Compression Load Button Load Cells – The Interface LBM Compression Load Button is constructed from stainless steel and has a small size for all types of sensor apps and testing. This product is available in capacities that range from 25 lbf up to 50K lbf.

There is a variety of other standard compression-only load cells, including modified and custom Interface compression testing options in multiple capacities. For more information on our compression-only products or any of Interface’s industry-leading force measurement solutions, contact our Application Engineers.

Interface Launches New University Program

Interface is investing in the engineers of tomorrow with our new Interface University Program.  The new STEM-focused initiative promotes innovation and education by providing access to the best force measurement products, services, and experts in the industry.

As the world’s leader in force measurement solutions, Interface created the specialized Interface University Program to provide discounted products and services, educational materials and access to renowned test and measurement expertise.

The distinct Interface University Program offers higher education institutions and students reductions on the industry’s most accurate and reliable force measurement standard products and calibration services to accelerate research and development, advance science, perform accurate testing, and promote exploration.

Through the unique program, Interface is also providing educational support in the form of internships, R&D projects, sponsored test and measurement class projects, grants, and community STEM program support.

“Our goal is to empower engineering students to achieve their educational and career goals with the help of our exclusive Interface University Program,” said Joel Strom, CEO, Interface. “The program will make critical engineering tools, services and professional support more accessible to universities and colleges faculty and engineering students. This program provides best in class test and measurement products, specialized solution bundles and discounts on products and services that will enrich engineering and metrology program experiences.”

The Interface University Program

Interface Standard Products:

  • Get Started Bundle with Interface LowProfile®, Sealed S-Type and Mini Beam Load Cells, Torque Transducer, Indicator and more at 25% off
  • Load Cell 101 Field Guide by Interface Engineers
  • 10% off all standard products and additional loyalty program discount programs

Interface Calibration and Repair Services:

  • Tiered Calibration Services Program discounts
  • Expedited repair services with special discounts
  • 25% off 3-year annual calibration services programs for maintenance

Education Support and Resources:

  • Internships for R&D at Interface HQ in Arizona
  • R&D projects
  • Sponsored test and measurement class projects or challenges
  • Failure testing projects
  • Onsite engineering hours: class, speaking, events

Interface provides force measurement solutions and services to hundreds of universities coast-to-coast and around the world every year. The company’s founder, Richard F. Caris, was a major proponent of charitable giving to STEM-focused institutions and programs. In 2015, Caris donated $20 million to the University of Arizona Richard F. Caris Mirror Lab to support the construction of mirrors used for the Giant Magellan Telescope. The Mirror Lab has utilized Interface products in its mirror polishing process for the past twenty years.

“Interface has been a long-time partner of the University of Arizona,” said Buell Jannuzi, Ph.D., Steward Observatory director and head of the Department of Astronomy, University of Arizona. “Their commitment to STEM and support of the Mirror Lab has been critical to our efforts, as well as the education of our students.”

For more information on the program and for a detailed breakdown of special offers, services, and educational support, please visit /university-program/ or contact our Application Engineers at 480-948-5555.

PRESS RELEASE

University Program Overview

University Program 2 Page