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Load Cell Test Stands 101

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Load cell test stands are important devices for manufacturers and testing engineers who need to measure the force or torque applied to an object, test specimen, or product. They are typically made up of a frame, one or more load cells, software, and data acquisition instrumentation.

How do load cell test stands work?

Interface load cells are sensors that convert force into an electrical signal. This signal is then amplified and sent to the test stand’s software, which displays and records the force data. The software can also be used to control the test stand, such as setting the speed and duration of a test.

Test stands are used to hold the test object or device and apply force or torque to it. They should be designed to provide a stable and consistent testing environment. It is typically designed to accommodate a wide range of objects of different sizes and shapes. Often a reconfigurable structure to adapt from test to test.

Test stands may have various components, such as a base or base plate, columns, a crosshead, and load introduction devices. Interface provides high-accuracy load cells, instrumentation and DAQ systems, software and accessories designed for use in various types of test stands.

What are the different types of load cell test stands?

There are two main types of load cell test stands: motorized and manual. Motorized test stands are more advanced and can be used for more demanding testing applications. They typically have features such as programmable speed and force control, as well as data logging capabilities. Manual test stands are less expensive and easier to use, but they are not as versatile as motorized test stands.

A test stand and a load frame are both mechanical structures used in materials testing, but they differ in their functions and designs.

The test stand can be a test bench or structure on a test bed plate. These assemblies are designed to rigidly hold an object while it is being subjected to external forces. These forces could be introduced from all angles and orientations and cover low cycle design limit to long duration fatigue cycle testing.

A load frame, on the other hand, is a machine that is specifically designed to apply and measure axial or torsion forces during material or small component testing.

Most Common Requirements for Load Cell Test Stands

Testing professionals, engineers and metrologists require a load cell test stand to perform accurate and precise measurements. The primary features of a test stand include:

  • High accuracy: The load cell test stand must be able to measure force or torque with a high degree of accuracy. This is important to ensure that the measurements are reliable and repeatable. Confidence in the data must be validated through accuracy of measurement.
  • Versatility: The load cell test stand must be able to be used for a variety of testing applications. Test lab professionals, engineers and metrologists need equipment that can perform a wide range of product and material tests. This also includes interchangeable sensors, depending on the capacity and type of test, such as tension or fatigue.
  • Repeatability: The load cell test stand must be able to repeat measurements with high precision. This is important to verify the accuracy of measurements over time, through continuous use and even high cycle counts.
  • Safety: The load cell test stand must be safe to use, even when testing products under high loads. Measurements are not compromised by safety concerns.
  • Ease of use: The load cell test stand must be easy to use, even for users with limited technical knowledge. This is important for testing professionals to be able to quickly and easily set up and use the test stand.

Load cell test stand requirements can vary based on the type of testing projects and materials. Many test stands are standard; however, complex testing programs often require custom test stands that are designed and calibrated for specific use cases. Interface provide load cells, instrumentation and software designed for use in test stands.

Test Stand Sensor Considerations

  • Ensure sensors are properly sized for capacity, cycle, and extraneous load considerations.
  • Multiple bridges are good feature for redundancy and data validation.
  • Thread adapters and connector protectors must be considered in choosing the sensor for a specific test stand application.
  • Multi-axis data capture often requires robust instrumentation to take full advantage of the data.
  • Invest in versatility and ruggedness to maximize return.

Additional Test Stand Options

  • Programmable speed and force controllers help to regulate the rate at which the load is applied to the product, as well as the maximum force that can be applied during a given test period or cycle.
  • Data logging instrumentation records the force data for each test. This data can then be used to analyze the results of the test and to make sure that the product meets the required specifications.
  • Remote monitoring and controls help with test stand use from a remote location. This can be useful to run tests without being physically present at the test stand.

There are many different types of load cell test stands, so it is important to choose one that is right for your specific needs. When selecting or building a load cell test stand, consider the weight or force that you need to measure, the accuracy and precision, the environment in which the test stand will be used and the equipment budget.  This is a topic we detailed in our Testing Lab Essentials Webinar. Watch this portion of the online technical seminar below.

Load Cell Test Stand Use Cases and Applications

  • Aerospace test stands are used to measure the strength of aircraft structures. Test stands are used to test the performance and durability of aircraft components, such as wings, fuselages, and engines. They are also used to test the structural integrity of aircraft materials, such as composites and metals.
  • Material test stands can be used to exam the strength, stiffness, and toughness of materials.
  • Structural test stands are used for small capacity testing, as well as large amounts of force to measure the structural integrity of buildings, bridges, and other formations.
  • Dynamic test stands are used to measure the performance of products under different environmental conditions, such as shock and vibration testing.
  • Medical manufacturers need to test the performance of medical devices. Test stands are used to test the performance and durability of medical devices, such as pacemakers and defibrillators. They are also used to test the accuracy of medical instruments and in-home medical equipment, as the safety of user is paramount to all other requirements.
  • Automotive labs use test the performance of engines, transmissions, brakes and other components. They are also used to test the durability of automotive materials, such as tires and plastics.
  • Consumer product manufacturers and OEMs must test the durability to ensure customer satisfaction and reliability of the product. Test stands are used in testing toys, appliances, tools, and electronic devices.
  • Industrial automation component makers and OEMs must test the strength of machine parts and materials used in product lines, machine tools, and robots. They are also used to test the safety of industrial equipment, such as forklifts and cranes.

Load cell test stands are an essential tool to accurately measure the forces acting on a test specimen. By using a load cell test stand, testing engineers can ensure that their equipment is operating within its design limits and that it is safe to use. If you have questions about building or upgrading your test stand, be sure to consult with our application engineers.

Interface Supports Wind Tunnel Testing

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In the development of an airborne vehicle, like a plane or helicopter, wind tunnel systems are used to gather data across a variety of tests related to the aerodynamics of the vehicle’s design. Whether an object is stationary or mobile, wind tunnels provide insight into the effects of air as it moves over or around the test model. Interface is a supplier of measurement solutions used for aircraft and wind tunnel testing.

Wind tunnels are chambers that test small scale model versions of full systems, or in some cases, parts and components, depending on the size and capabilities of the wind tunnel. They work by allowing the engineers to control airflow within the tunnel and simulate the types of wind force that airplanes and other aircraft will experience in flight. Wind tunnels are also used for testing automobiles, bicycles, drones and space vehicles.

By taking careful measurements of the forces on the model, the engineer can predict the forces on the full-scale aircraft. And by using special diagnostic techniques, the engineer can better understand and improve the performance of the aircraft.

The process for measuring the force and how it reacts to this force works by mounting the model in the wind tunnel on a force balance or test stand. The output is a signal that is related to the forces and moments on the model. Balances can be used to measure both the lift and drag forces. The balance must be calibrated against a known value of the force before, and sometimes during, the test.

Interface’s strain gage load cells are commonly used in wind tunnel testing due to their quality, accuracy and reliability. The instrumentation requirements often depend on the application and type of test. The range of options for both load cells and instrumentation vary based on scale, use, cycle counts, and data requirements.

Instrumentation used in wind tunnel testing can be as simple as our 9325 Portable Sensor Display to a multi-channel data acquisition system. Interface analog, digital and wireless instrumentation solutions provide a range of possibilities. As is the case, wind tunnel testing is typically very sensitive. It is important to calibrate the instrumentation before each test to measurement accuracy.

Types of Wind Tunnel Tests Using Force Measurement Solutions

  • Lift and drag: Load cells are used to measure the two most significant forces that impact aircraft design. Lift is the force that acts perpendicular to the direction of airflow and keeps the craft airborne. Drag is the force that acts parallel to the direction of airflow and opposes forward motion.
  • Side force: This force acts perpendicular to both the direction of airflow and the lift force. It is caused by the difference in pressure between the upper and lower surfaces of the aircraft.
  • Moments: Moments are the forces that act around a point. The most common moments measured in wind tunnels are the pitching moment, the yawing moment, and the rolling moment.
  • Stability and control: Tests conducted to measure the stability and controllability of an aircraft are commonly using force measurement solutions for aircraft design changes or integrating new parts into an existing model.
  • Performance: Particularly important with new designs, engineers use these tests to measure the simulated flight performance under maximum speed, range and fuel efficiency.

The specific tests that are conducted in a wind tunnel depend on the project requirements.

Multi-Axis Sensors for Wind Tunnel Testing Applications

In measuring the forces of a wind tunnel test, multi-axis sensors offer the perfect solution for collecting as much data as possible across every axis, giving the engineer a more complete picture on the aerodynamics of the plane. In fact, Interface has supplied multi-axis load cells for use in several wind tunnel testing applications, for OEMs, testing facilities and part makers.

We offer a variety of multi-axis options including 2, 3 and 6-axis standard and high-capacity configurations depending on testing and data requirements of the user. These sensors can precisely measure the applied force from one direction with little or no crosstalk from the force or moment. Interface products provide excellent performance and accuracy in force and torque measurement.

To match the demands of the volumes of data available using multi-axis sensors in wind tunnel testing, Interface often provides several data acquisition instrumentation solution along with our BlueDAQ software.

Wind Tunnel Test Application

A major aerospace company was developing a new airplane and needed to test their scaled model for aerodynamics in a wind tunnel, by measuring loads created by lift and drag. Interface Model 6A154 6-Axis Load Cell was mounted in the floor of the wind tunnel and connected to the scaled model by a stalk. The wind tunnel blew air over the scaled model creating lift and drag, which was measured and compared to the theoretical airplane models. The output of the 6-axis sensor was connected to the BX8-AS Interface BlueDAQ Series Data Acquisition System, which was connected via USB cable to a computer. Using this solution, the company was able to analyze the collected data and made the necessary adjustments in their design to improve the aerodynamics of their theoretical airplane models.

Interface supports wind tunnel testing and all uses of force measurement in the advancements in aeropspace.

Wind tunnel testing is critical to the aircraft industry, as well as other industries like automotive and space. Interface has been providing multi-axis sensors and strain gage load cells to industry leaders and wind tunnel operators. We understand the unique needs of this type of testing and the instrumentation options that work best with our high-accuracy sensors. We also can work to provide custom solutions, load cells for use in extreme environmental conditions. Contact us to get the right solution for your specific testing program.

Additional Resources

Aircraft Wing Fatigue App Note

Airplane Jacking System

Interface Airplane Static Testing Case Study

Taking Flight with Interface Solutions for Aircraft Testing

Aircraft Yoke Torque Measurement

Aircraft Screwdriver Fastening Control App Note

Interface’s Crucial Role in Vehicle and Urban Mobility Markets

Rigging Engineers Choose Interface Measurement Solutions

 

Interface and Testing Lab Applications

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Test and measurement impacts nearly every industry.  At Interface, we classify Test and Measurement (T&M) as it’s own solutions market. Though testing is generally a service, the accuracy and quality equipment and tools that are required for performing these T&M services has created an industry in itself.

Throughout the Test and Measurement industry, there are several different classifications and testing lab types. Each of these different testing labs provide unique equipment for different forms of testing depending on the application, system or component. These different types test labs include:

  • Structural testing labs perform tensile, compression, bending, fatigue and hardness testing on materials, components, or assemblies.
  • Environmental testing labs evaluate the impact of environmental factors on products, components, or materials performing temperature, humidity, salt spray, and vibration testing.
  • Electrical testing labs determine the electrical properties of components or products using insulation resistance, electrical continuity, and dielectric strength testing.
  • Chemical testing labs determine the composition and purity of materials using chromatography, spectroscopy, and elemental analysis.
  • Product safety testing labs ensure that products meet safety and regulatory standards with flammability, toxicity, and durability testing.
  • Calibration testing labs ensure that measuring instruments and equipment are accurate and reliable. Common disciplines include force, torque, pressure, temperature and physical calibration. Read more: Interface Calibration 101
  • Non-destructive testing labs evaluate the integrity of materials with ultrasonic testing, magnetic particle inspection, and radiography.

Here at Interface, we are deeply ingrained in supplying nearly every type of testing lab out there with precision T&M devices, from the world’s best force measurement sensors to advanced instrumentation. Interface offers one of the most diverse force, torque, and weight related force sensor product lines in the market. It is why labs prefer Interface. In addition to our expanding line of  data acquisition systems, software and accessories, T&M engineers and lab pros find Interface as a one-stop-shop for simple and complex testing projects.

Testing Lab Applications Using Interface Products

Material Testing Lab – Press Form Monitoring

Customer Challenge: Press forming is a method to deform different materials. A force measurement solution is required to monitor the forces being applied by the press forming machine to ensure quality control and traceability during the production process.

Interface Solution: For large press forming machines, Interface recommended installing the 1000 High Capacity Fatigue-Rated LowProfile™ Load Cell. When the material was placed under the punch plate to form a shape, the force applied was measured and results were sent to the INF-USB3 Universal Serial Bus Single Channel PC Interface Module, where results can be graphed and logged.  Read: Press Forming and Load Monitoring

Medical Testing Lab – Specimen Research Linear Test Stand

Customer Challenge: Medical experts need the best equipment during research of multiple specimens. In this case, a medical researcher needed to monitor the load force of their linear actuator that uses a needle to collect material from the desired specimen.

Interface Solution; Interface’s SuperSC S-Type Miniature Load Cell was easily installed into the linear test stand. A needle with a gripper on the end was installed on the lower end of the SuperSC. As the needle is pushed to collect material of the specimen, the load feedback is captured using the 9330 Battery Powered High Speed Data Logging Indicator.  Read: Specimen Research App Note

Safety Test Facility – Bike Helmet Impact Test

Customer Challenge: A company wanted to test the impact of a bike helmet when dropped from different heights, onto a flat surface such as an anvil. This test is necessary to ensure consumer safety, and that their products are made of the highest quality until sold to the public.

Interface Solution: Interface suggested installing our 1101 Compression Only Ultra Precision LowProfile™ Load Cell at the bottom of an anvil. The bike helmet was then dropped from multiple heights, at multiple angles, onto the anvil. The measurements from impact were then recorded and logged using our INF-USB3 Interface Module.  Read: CPG Bike Helmet Impact Test

Product Test Lab – Touch Screen Force Testing

Customer Challenge: Touchscreen kiosks used in restaurants, retail and entertainment venues all need various tests to be performed to ensure functionality and sensitivity. One of those tests are force tests that touch screens to withstand high use by all types of consumers.

Interface Solution: Interface’s SMTM Micro S-Type Load Cell was installed on the customer’s force testing machine. The touchscreen was laid flat under the machine, and force tests were conducted in different locations of the touchscreen. With supplied BlueDAQ software, results are captured and reviewed using the 9330 Battery Powered High Speed Data Logging Indicator through an SD card.

These are just a few examples of where Interface products are involved in a wide variety of different testing labs and how T&M engineers are utilizing them. To learn more, check out our new Testing Lab Essentials webinar, which can be found here.


ADDITIONAL RESOURCES

Testing Lab Essentials Webinar Recap

Introducing the Interface Consumer Product Testing Case Study

Interface Solutions for Safety and Regulation Testing and Monitoring

Electric Vehicle Structural Battery Testing

 

Basics on Load Cell Base Kits

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As resilient and accurate as load cells are engineered, there is risk of damaging a load cell if they are not properly supported through mounting or mating to the test subject or test bench.

Load cell bases are designed to support and stabilize load cells. Load cell bases come in assorted sizes and configurations, depending on the intended application and the weight capacity.

Load cell bases are used with load cells that are frequently utilized in industrial equipment, test machines, and commercial testing labs. They may also be integrated into several types of equipment, such as weighbridges, conveyor systems, structural test stands, and packaging machines.

Interface publishes numerous guides on properly supporting a load cell during a test. However, for our LowProfile™ load cells, we provide complete Load Cell Base Kits to provide the engineered accuracy and necessary support for precision performance as intended in regular use. Bases minimize risks in damaging load cells from improper use.

Load cells with positive overload protection must be ordered with an Interface installed base. The positive overload option is useful when high overloads occur in applications such as: impact loads on weighing platforms; engine malfunctions during rocket or jet engine testing; transient overloads on engine dynamometers.

Interface’s Load Cell Base Kits are a type of mounting plate guaranteed to provide optimum support for the flexure. Using the base, or a support surface with its equivalent flatness and stability, is required to ensure the exceptional performance. They are heat treated and high strength bases, available in all standard sizes of our low profile models.

Standard thread size is the same as the mating load cell. Bases or flat mounting surfaces are required for all low profile load cell installations. A mounting surface that is flat to 0.0002″ T.I.R. (total indicator reading) is required, unless a base is installed.

Use of the base, or a support surface with its equivalent flatness and stability, is required to ensure the exceptional performance of the LowProfile® Series.

The threaded hole in the base is on center, and a plug is permanently installed to seal dirt and moisture out of the space between the bottom hub of the flexure and the flat surface of the base. Center hub deflects under the load until it contacts the base which provides positive overload protection. The center tapped hole is sealed to keep overload surfaces clean.

When the base and load cell are ordered together, the base and plug are factory installed using the proper hardware tightened to the required torque specs. A plug is supplied in between the cell and the base to prevent damage or errors caused by over engagement of mating parts.

There are 14 model options in standard Load Cell Base Kits in both U.S. and Metric Threads. They are available for our standard 1000, 1100 and 1200 Load Cell Series of various capacities. We offer 15 stainless steel model options to be paired with our 2400 and 3200 Load Cell Series.

Load Cell Base Kits are an excellent accessory to ensuring the most out of your LowProfile Load Cells provide the performance as designed. For complete instructions on installations, please reference our Support section on the website.

ADDITIONAL RESOURCES

Accessories

Load Cell Basics Sensor Specifications

Interface Presents Load Cell Basics

Technical Library

Force Measurement Installation Guides

Mechanical Installation Load Cell Troubleshooting 101

New Product Release of Interface Force Verification Frames

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Interface, the leader in force measurement solutions, is excited to release three new models of the Interface Force Verification Frame for fast and efficient force measurement product verification.

The Interface Force Verification Load Frame is lightweight and easy to use, providing an on-demand and onsite solution for verifying the accuracy and reliability of load cells. Buyers are able to conduct load cell verification in real-time between calibration services for a wide range of types and sizes of load cells.

The new Interface load frame is lightweight and can be customized with multiple adapters to fit a wide range of different load cells. It is being sold in three different models based on the capacity needs of the user.

  • IFVF-1K model provides a capacity of 1,000 lbf
  • IFVF-2.5K model provides a capacity of 2,500 lbf
  • IFVF-5K provides a capacity of 5,000 lbf

Specifications and options details for each model, along with design file information and our technical user guide are available on the new product page here.

VIEW A DEMONSTRATION OF A VERIFICATION TEST STAND IN OUR NEW ANIMATED APP NOTE 

The mobile, lightweight design allows customers to pick up and carry the Interface Force Verification Frame directly to an in-process force test and conduct point-of-use verification in minutes. The typical process for verification can take a few days to a week or more, slowing down product test and development time significantly.

The wide range of adapters available for the new Force Verification Frame is designed so that Interface and many non-interface load cells can be verified with this system. This provides compatibility with load cells that Interface provides to industry leaders in aerospace and defense, automotive, medical, OEM, testing labs, energy, industrial automation, education, and metrology.

“Our customers need an easy-to-use test and measurement hardware apparatus that allows them to verify the accuracy and provide a quick check-up of their load cells fast, anywhere and at any time. We are pleased to offer our latest product, the Interface Force Verification Frame which gives customers a simple and efficient point-of-use verification system compatible across a wide range of industry applications and force measurement products.” –  Ted Larson, Vice President of Product Management and Marketing, Interface.

Additionally, customers rely on Interface for calibration services and products. Calibration services and systems preserve the industry-leading accuracy and reliability of Interface products. However, supplemental load cell verification could only be accomplished if customers owned a calibration system or shipped their products to a calibration lab. Now, the Interface Force Verification Frame allows customers to perform their own product accuracy tests quickly and more cost-effectively between annual calibration certifications. It also helps to determine when a product needs to be sent in for repair.

The Interface Force Verification Frame is available today. For more information on the available systems and custom options, contact an Interface Application Engineer at 480-948-5555 or request a quote here.

 

Exploring Aerospace Force Measurement Solutions

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The aerospace industry is responsible for some of the greatest inventions and innovation in our global history. The engineering and manufacturing of a single rocket engine design, using handwritten calculations and with less computing power than a modern smartphone, took us to the moon.

The NASA Parker Solar Probe is the culmination of some of the most impressive technology ever developed by mankind, journeying through the skies and beyond earth’s atmosphere with the ability to reach a top speed of 430,000 miles per hour.

The aerospace industry is an assembly of researchers, design houses, test labs and manufacturing companies that engineer and build vehicles to travel within and beyond Earth’s atmosphere. The range of aircraft and space vehicles include all types from unpowered gliders to commercial and military aircraft, as well as rockets, missiles, launch vehicles, and spacecraft. The term aerospace comes from the combination of the words aeronautics and spaceflight. All of these vehicles go through extensive and rigorous test and measurement programs and processes.

For more than half a decade, Interface has served some of the most prominent aerospace organizations in the nation including NASA, Boeing, Northrop Grumman and more. Our sensor technology has been used to design, test and manufacture airplane frames, wings, landing gear, rocket engines and even the machines that build the components for these products. These projects require the most precise data available, not only to ensure that the airplane or spaceship can fly and land, but more importantly to guarantee its safety for the pilot, crew and passengers.

Interface is humbled and proud to provide critical force measurement solutions and technology to the aerospace industry, in support of science, innovation and exploration.

Interface is often selected by our aerospace customers over the competition because we offer the most accurate and reliable force measurement products on the market. In this blog, we will be outlining how Interface serves the aerospace industry in validating designs, improving performance and maintain the highest safety possible.

AIRCRAFT

One of the most important tests to run in aircraft development is static and fatigue testing on the frame of the aircraft and the wings. Engineers will often simulate the effects of various forces on the aircraft and wings with actuators which act as of wind, weather, debris and more. Hundreds of Interface load cells are used to measure those forces to either validate the simulations or find errors in order to adjust the simulation and design accordingly. Load cells are also used on the machines controlling these forces in the test environment to ensure the actuators are simulating the right amount of force.

READ THIS APP NOTE FOR AIRCRAFT WING FATIGUE TESTING

ROCKETS

For a spacecraft that can weigh up to 1,000 tons, you need a lot of force to get it off the ground and safely out of the earth’s atmosphere. One of the ways that engineers test the thrust force of a rocket engine is with load cells. During these tests, the engine is attached under the mounting plate, which is part of a test stand. Interface load cells are installed between the plate and test stand and when the rocket thrust pushes up on the plate, the load cells relay the force data to the engineers. These tests help engineers make adjustments to the engine to use the precise amount of force to lift the craft into space, but not too much so that it doesn’t burn up too much fuel.

READ THIS CASE STUDY: LAUNCHING INTO ORBIT WITH INTERFACE

AEROSPACE MANUFACTURING

Before the air and spacecrafts are even assembled, the components need to be manufactured in a plant. There are hundreds of machines that are used on the production line for the hundreds of thousands of components needed to complete the craft. Interface load cells and torque transducers can be found on many of these machines. Not only are they used to help test the machines, they are also used to measure various forces on the machines in real-time. Our products are used to provide a wealth of insight to tell the manufacturers if the machine is working properly, needs to be recalibrated or needs repairs.

READ THIS APP NOTE FOR ROCKET STRUCTURAL TESTING

For more information on the numerous applications of Interface products in the aerospace and space industry, visit our solutions page at www.interfaceforce.com/solutions/aerospace/. Here you can read application notes and browse the various products we offer for our customers.

To watch an actual aircraft structural, check out this great Airbus video of an actual test.

Contributor: Randy White, Regional Sales Director at Interface