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Can Load Cells Be Repaired?

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Load cells are very resilient. Most are constructed with sturdy materials that can withstand long and arduous cycling and multitudes of testing projects. In fact, with proper treatment, regular calibration services and use within specifications, load cells can last many years. Even with such high quality and durability, it is important to perform regular diagnostic checks of a load cell to maintain the health of any force measurement device.

FACT: Interface has load cells that are in use today that we manufactured several decades ago. As the saying goes, Interface load cells are built to last.

A load cell can be damaged or lose accuracy. Load cells can be repaired depending on the extent of damage. Some common issues such as cable damage, electrical faults, or environmental factors can be repaired by replacing parts or recalibrating the load cell. However, more severe damage such as physical damage to the load cell itself may make it beyond repair and require replacement.

What is the most common type of damage to a load cell?

Most often, a load cell is damaged by overloading or exceeding its rated capacity. This can result in physical deformation or strain on the load cell, leading to permanent damage and reduced accuracy.

Other common causes of damage to load cells include exposure to harsh environmental conditions such as extreme temperatures, moisture, or corrosive substances, as well as electrical faults such as voltage spikes or short circuits. Additionally, mechanical stress from improper installation or handling can also cause damage to load cells.

What steps should be taken to evaluate a load cell that might be damaged?

  • Visual Inspection: Ensure that the physical installation, correct interconnection of components and the system are all intact. For example, has the load cell been dropped or have any damage to connectors or adapters? Reference the installation and operation manuals available with each product.
  • Electrical Testing: Use an Ohmmeter to check the bridge circuitry and zero balance. Evaluate the resistance and output of the load cell. If there is a notable change in resistance or output, it may indicate that the load cell is damaged. This is also a good time to check the troubleshooting guide.
  • Test Loads: Apply a range of test loads to the load cell and observe if the readings are consistent and within the expected range.
  • Calibration: If the load cell is not functioning correctly, recalibrate it using a weight calibration system or load cell calibrator to see if the readings are within the expected range.
  • Professional Evaluation: Request a thorough inspection of the device to determine the load cell can be repaired or needs to be replaced.

It is important to follow safety protocols and to use proper equipment and techniques when evaluating a load cell to avoid causing additional damage.

After a thorough physical inspection along with mechanical and electrical installation checks, it is determined that a load cell is not performing to specifications it is time to contact the manufacturer for Services & Repair to schedule a return of the product for further evaluation and potential load cell repair.

Use Cases for Frequent Calibration Services and Repair Evaluations

  • Harsh environmental conditions can cause corrosion and electrical failures
  • Loading forces that exceed the load cell rated capacity can cause shifting of the zero-load output of the load cell
  • Moment loading of the load cell can cause zero shifts and other undesirable behavior
  • High cycle rates or fatigue applications can cause premature failure

Many of these symptoms can be repaired or mitigated if they are identified early during appropriate evaluation and calibration cycles. In addition, load cells are prone to losing accuracy through normal wear and tear and ageing. There are times when loading conditions and use case environments necessitate the need for more frequent evaluation and calibration cycles. The process of calibration can include adjusting the measuring instrument to bring it in alignment with the standard specifications.

It is always recommended that users consult an application engineer or user’s manual to avoid situations where a load cell can be damaged or degrade accuracy too quickly. Interface has deeps expertise in repair and calibration, built and proven over 55 years in the business of making and calibrating load cells.

Interface provides repair evaluation and services on load cells we make and from other manufacturers. Repairs include a complete evaluation of the device prior to repair and calibration upon completion. Our standards for calibration are world-class. Our calibration labs are managed by experts in diagnostics, testing and repair with engineering and metrology grade equipment designed by the leaders in force measurement.

If you’re already a load cell user and have not had your products calibrated in some time, we recommend scheduling your calibration service online here. Load cells can provide years and years of quality data as long as they are properly taken care of. Put your trust In Interface to make that happen.

Additional Resources

Services & Repair

Mechanical Installation Load Cell Troubleshooting 101

How Do Load Cells Work?

Regular Calibration Service Maintains Load Cell Accuracy

System Level Calibration Validates Accuracy and Performance

 

Recap of Accurate Report on Calibration

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Interface recently hosted an in-depth discussion on the topic of calibration.  As one of the largest calibration labs in the world for force and torque sensors, our team shared insider tips, frequently asked questions, set up techniques and best practices in the lab during this extensive calibration webinar.

The ForceLeaders seminar also covered details about various calibration grade equipment like our 1800 Platinum Standard® Calibration LowProfile® Load Cell, 1600 Gold Standard® Calibration LowProfile® Load Cell, fixtures, load frames, and calibration systems.  We also delved into topics that include instrumentation, verification frames and software.

During the event, we covered a diverse set of subjects due to the range of experiences of our attendees including the top five reasons why calibration matters, the measurement of uncertainty, identifying errors and the parameters of calibration.

You will find the recorded event Accurate Report on Calibration is available to review the technical details related to each of these important calibration subjects.

Elliot Speidell, Brian Peters and Chris Brandenburg covered a wide range of topics, including:

  • The Metrology Perspective
  • Interface Calibration Methodology: What, Why & How
  • Top 5 Reasons Why Calibration Matters
  • Calibration and Measurement Uncertainty
  • What Errors are Characterized in the Calibration Process?
  • System Calibration Considerations
  • Calibration Lab Set Up Best Practices + Tips
  • Optimization + Calibration Applications
  • Fixtures + Standard Equipment
  • Interface Calibration Services
  • Do & Don’t Tips + FAQ

To get things started, we began the event with a quick conversation about metrology, the science of measurement, which embraces both experimental and theoretical determinations at any level of uncertainty in any field of science and technology.

Metrology is the global network standardizing measurement units. Calibration is the action taken at each step in the metrology network.

Metrology is important to Interface because it provides the standards for controlled processes, systems, reliability, accuracy, quality and science. Calibration is the set of operations that compares the accuracy of a measuring instrument of any type, such as a load cell or torque transducer, against a recognized standard. The process of calibration includes adjusting the measuring instrument to bring it in alignment with the standard.

Why is calibration of load cells and torque transducers important?

  • All load cells are subject to performance degradation due mistreatment, drift, or aging
  • You need traceability and quality system requirements
  • Pre and post-test verification is critical for data validity
  • Even load cells manufactured to the highest standards require regular calibration

Interface calibrates every load cell and torque transducer to spec before it leaves our facility. We also provide recalibration services for all types of devices, even those we don’t manufacturer. This results in more than 100,000 calibrations every year by our trained technicians. During this event we shared valuable tips for setting up and operating a world-class calibration lab.

Best practices for calibration labs:

  • Define workspace requirements
  • Qualify measurement types and models
  • Identify suppliers
  • Select calibration grade equipment
  • Assemble lab
  • Train lab techs
  • Create certification and testing protocols
  • Define workflows
  • Utilize software for tracking assets and certificates
  • Know maintenance and recalibration schedules

The Accurate Report on Calibration recorded event is available online to watch at your convenience.

If you need help in defining the best calibration grade systems or equipment for your specific test environment, contact our application engineers.  If you need a calibration service, you can submit your request online.

Interface Calibration 101

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Calibration of force and torque sensors is critical to receiving accurate data from measurement testing.  Calibration is the comparison of the instruments output against the known standard of measurement. For a load cell, it is the comparison of the load cell output against the standard test loads.

The calibration ensures the sensor is performing accurately and set for ideal output based on the capacity and configuration of the design. A standard calibration tests repeatability and linearity, which are both used to determine the accuracy. Calibration tests are run to identify any potential measurement errors caused by zero offset, non-linearity, hysteresis, non-repeatability, and shifts from zero.

The team of calibration experts at Interface are specifically trained to provide this specialized service as part of our quality and lab standard requirements of operations. Interface is ISO/IEC 17025:2017 and A2LA Accredited for Torque and Force Calibration in accordance with the recognized International Standard ISO/IEC 17025:2017.

Interface certifies all our load cells with accredited calibration before releasing the product for shipment. Certificate information includes tabulated measurement variables data, zero balance, computed nonlinearity and hysteresis, and traceability statements. We are often recognized as the most complete calibration certification in the industry

In a recent customer survey, we found that one of the most important roles that Interface force measurement solutions play is for our calibration services. This is due to the accuracy, reliability, and dependability over long periods of time of the load cells we manufacture and service.

Why Calibrate?

Calibration is important based on many different factors, including continued performance, safety, and compliance with ISO or industry specific standards. Interface’s standard recommended calibration interval is to recalibrate every 12 months. The frequency of calibrations should be determined by the following use case factors that may affect measurement accuracy:

  • Measurement quality and allowable tolerance range
  • Level of stress to which the equipment is subjected
  • Stability of past calibrations
  • Required measuring accuracy
  • Quality assurance requirements

Interface Calibration Services

Interface provides calibration and repair services on load cells and torque transducers, including devices made by other sensor manufacturers. In fact, Interface performs more than 100,000 calibrations every year. This includes new products as well as devices sent to Interface for recalibration and repair. Repairs include a complete evaluation of the device prior to repair and calibration upon completion.

In addition, here are some other benefits for choosing Interface as your calibration services partner:

  • ISO 17025 Accredited
  • Scheduled Repairs for Ongoing Inventory Management
  • Custom Calibration Services
  • RMA Tracking and Permanent Archive of Test Data
  • NMI Certified Gold and Platinum Standard Reference Load Cells
  • Interface Gold Standard Calibration Software Used for Data Collection and Analysis
  • Full-Service Machine Shop for any Mechanical Requirements

Calibration Services Process

The Interface calibration team consists of a team of professionals dedicated to an optimized calibration and repair process for timely management of our customer’s requests. We begin the calibration service process with our technical services group who manage the request and RMA process, in addition to evaluation and troubleshooting.

We evaluate all products at our headquarters with our team of experts. The sensor goes through a thorough inspection process to identify any necessary repairs and to ensure device is in working condition in preparation of a calibration. This includes an electrical test. Based on the extensive evaluation, if the device is found to be unrepairable, there is no charge. We also will work to find a replacement unit. All work beyond the evaluation is sent to the customer for approval.

The final step in our calibration services process is the actual calibration. Our calibration team is considered the most experienced in the industry due to the sheer volume of work product they calibrate every day.  Interface also is heavily invested in conducting all our calibrations with the most advanced equipment, including our proprietary Gold Standard® and Platinum Standard® systems. These machines ensure that the transducers are calibrated to the most accurate ability possible before returning to the customer.

Even the most high-end manufactured load cells and finely tuned components endure accuracy degradation over continued use. To ensure your sensors are always ready for peak performance, check out our calibration services request form. We also provide a full range of calibration grade products for metrology and testing labs. You can also give us a call at 480-948-5555 to discuss your specific calibration needs.

 

Faces of Interface Featuring Elliot Speidell

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In today’s Faces of Interface post, we are featuring Interface National Sales Director Elliot Speidell. Amongst all the wonderful stories and backgrounds, we hear about from our amazing team, Elliot’s may be one of the most unique and interesting.  You see, Elliot didn’t start his career in or go to school for engineering like many of the Faces of Interface subjects we’ve highlighted in the past.

In fact, Elliot studied music education at Northern Arizona University. Music was Elliot’s first passion and he thought that he would go on to pursue a career in it. Although, as he explains it, he was a kid just trying to figure it out and wasn’t sure what to do. But he loved music, so he went for it.

His first job out of school was teaching music in elementary school, followed by teaching both middle and high school students. And while he did enjoy it for a time, he and his wife were expecting a daughter and he thought that it was time for a change.

Now, music isn’t Elliot’s only passion. He also loves to work with cars. He can often be found tinkering and improving cars that he eventually races in Sports Car Club of America Solo (SCCA) events. SCCA Solo is different from what you see on TV with NASCAR and Indy Car Racing. It involves precision driving through a designated course marked with cones. If you’ve kept up with the Faces of Interface series, you would know that SCCA Autocross is also a major hobby for our Global Sales Vice President, Brian Peters.

Going back to Elliot and his desire to move into a new field, both Brian and Elliot became friends during SCCA competition, and Elliot had mentioned to Brian that he was looking for something new. Knowing Elliot well, Brian thought that he would make a great application engineer. Thus, the unique story of how Elliot moved from music to a career in technology and engineering by joining the team at Interface.

As an Application Engineer at Interface, Elliot provided frontline support to customers across the east coast, later moving to serve the west coast. He worked across industries providing force measurement solutions to customers for a wide variety of applications. After a few years, he moved on to the newly introduced technical services department where he served as the technical services manager. In this role, Elliot and his team helped manage the recalibration of customer’s products as well provided technical support to customers for load cells, torque transducers, and related instrumentation. He was also instrumental in selling these services to customers and growing the technical services business.

Elliot was promoted to regional sales director starting on the west coast and eventually taking over support for the region that is along the US east coast, as well as a few regions in the south including Texas, Louisiana, Arkansas, and Oklahoma. The  role is more strategic in nature in that he’s out working directly with customers providing Interface force solutions, while also working directly with Interface’s teams of outside sales reps in those regions.

Today, he is the national sales director for Interface. He is responsible for all the regional sales directors and application engineers covering the United States.  He works directly with our sales network and supports key accounts. His promotion is based on years of experience and dedication to helping customers find the right solutions for all their test and measurement needs.

The thing that Elliot loves most about working at Interface is the diversity of applications he gets to work on. One day he could be helping provide a solution for measuring the tension on a guitar string and another day he’s helping a customer that’s working on a test stand for a rocket engine. Every day is unique and the technology he gets to see, and help solve challenges for, is always getting cooler!

When he’s not solving customer challenges, Elliot can be found with his wife of 14 years and their daughter, riding his mountain bike, or in the garage slowly working on LS swapping his car’s engine for SCCA autocross. Pre-pandemic, he also still indulged his love of music by playing trumpet in a Soul and Funk band at various Phoenix area venues.

We hope you enjoyed learning about Elliot as much as we enjoyed sharing this feature. Stay tuned for more Faces of Interface in 2021, and from everyone here at Interface, we wish you a very happy New Year!

Understanding Uncertainty in Load Cell Calibration

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In force measurement testing, accuracy is the most critical factor in ensuring the data you collect can help to identify challenges, failures and opportunities in the product design and development cycle. Here at Interface, we have mastered the art of load cell accuracy by employing a vertically integrated manufacturing process that allows us to control the development of our products most critical components.

Even the most high-end manufactured load cells and finely tuned components endure accuracy degradation over continued use. Therefore, we have also invested in equipment and talent with deep expertise in load cell recalibration, as well as offering gold and platinum standard calibration systems to customers. Recalibration is recommended on an annual basis, or of course, whenever our customers feel they need to confirm they are getting the right data out of their load cells.

One of the key factors of calibration and recalibration is understanding how to estimate practical uncertainty in load cell calibration. Measurement uncertainty is defined as an estimate of the range of measured values within which the true value lies or, alternatively, the degree of doubt about a measured value. In every application, there will be an uncertainty requirement on the force measurement. The equipment used to make the measurement must be traceable to a realization of the SI unit of force (the newton) within this required uncertainty.

Each application is different in terms of its uncertainty requirement. For instance, an application testing force in the aerospace and defense or medical sector will include a much more stringent uncertainty requirement than something like a commercial scale used to measure someone’s weight or food. It is critical to understand the uncertainty requirement on the application to ensure the force measurement device used is calibrated to handle the project.

How does one go about estimating uncertainty in load cell calibration? The first thing to understand is the GUM, a guide to the expression of uncertainty in measurement. This guide establishes general rules for evaluating and expressing uncertainty in measurement that are intended to be applicable to a broad spectrum of measurements.

Next, we have included a list of different considerations, as we measure uncertainty here at Interface. These factors will help guide you as you determine uncertainty for yourself. This list includes:

  1. Determine what parameter is to be measured and the units of measure.
  2. Identify the components of the calibration process and the accompanying sources of error.
  3. Write an expression for the uncertainty of each source of error.
  4. Determine the probability distribution for each source of error.
  5. Calculate a standard uncertainty for each source of error for the range or value of interest.
  6. Construct an uncertainty budget that lists all the components and their standard uncertainty calculations
  7. Combine the standard uncertainty calculations and apply a coverage factor to obtain the final expanded uncertainty.

It is also important to consider the different methods of load cell calibration. There are three different methods, and each has an approximate feasible expanded uncertainty. The different calibration methods include:

  • Direct dead weight – this method is the best for accuracy at 0.005% uncertainty, but it is slow, and the equipment is space inefficient.
  • Leveraged dead weight – middle of the road for accuracy at 0.01% uncertainty, and slow and space inefficient.
  • Hydraulic force generation comparison – this method has reasonable accuracy at 0.04% uncertainty and is also the fastest and most space-efficient option.

The final point is the sources of error in calibration. Error is defined as the difference between the measured value and the true value. There is a long list of different factors that can cause error and increase uncertainty. These factors may include drift, creep, misalignment, or environmental factors such as temperature. To compensate for this, it is important to understand the various formulas that can be used to find the true value based on the given measurement and the various factors for error.

To learn more about uncertainty and the different ways users can address uncertainty and overcome it, please give us a call at 480-948-5555, or visit our website to contact our Application Engineers.

Contributor:  LaVar Clegg, Interface

Source: NCLSI Measurement Training Summit 2014

Faces of Interface Featuring Ken Bishop

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From the very beginning, force measurement has been a major part of Ken Bishop’s life. Growing up in Anaheim, California, his father worked for a company called Ormond, Inc., which produced load cells, rocket thrust stands, weighing products and scales. He got to know the people his father worked with and the cool technology they were working on. Therefore, it was no surprise that Ken would follow in his father’s footsteps shortly after graduating high school and working for Ormond himself.

Ken worked with his father at Ormond for five years. He held positions as a driver, an assembler, and then eventually worked his way into a technical management position. After Ormond, he took a brief break from the force measurement industry to join the expanding computing field. He worked at General Micro Systems, where he focused on single board computers. However, his true calling pulled him back and he rejoined the force measurement industry when he was hired at Sensortronics.

Sensortronics then became the first load cell company acquired by Vishay in 2002. Vishay is a global manufacturer of semiconductors and passive electronics and in the early 2000s they would end up acquiring three more load cell manufacturers after Sensortronics. Ken’s job became to work as a team member to consolidate the four companies in the Americas and create Vishay’s transducer group as the Operations Manager for the America’s. Ken oversaw this group for several years afterwards.

During his working career, Ken also began to focus on his post-secondary education. He took night classes for quite a while to earn several degrees. He started with an Associates of Science from Fullerton College. He then received a Bachelor of Science in Business Administration and Management, followed by a master’s degree in Business Administration, from the University of Redlands, in California.  His post-secondary education allowed Ken to excel faster in his career path.

After Vishay, Ken took a brief hiatus from the engineering world to get away from it all. He picked up and moved to Montana to enjoy the wide-open spaces and outdoor lifestyle. However, it was not long before the itch to make things returned. In 2006, Ken moved to Arizona and joined Interface.

Ken began his career at Interface on the sales team as an application engineer focused on the West territory. His job was to work with customers to deliver force measurement solutions for a wide variety of test and design challenges in the aerospace, industrial, medical, metrology and automotive sectors. He eventually worked his way up to become a senior application engineer.

During his time as an application engineer and senior application engineer, Ken realized that there were many customer challenges that could not be solved with an off-the-shelf solution. While Interface had worked on custom projects previously, there was no official department to head up the growing demand for custom solutions.

When the department was created, Ken was given the opportunity to become the custom solutions director. He jumped at the opportunity and created a solutions team that could meet the growing demands of Interface’s customers for systems and specialized products. Ken leads the development of custom force measurement solutions designed to meet the unique challenges of an evolving technology and manufacturing ecosystem.

If all this was not enough, Ken also leads the repair and recalibration services department with fellow Interface technical service manager, Chris Brandenburg. And, he has spent some time working on the marketing team. Ken has truly done and seen it all in the force measurement industry.