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 S-Type Load Cells 101

There are many different types of devices used in test and measurement from load cells to torque transducers and tension links to multi-axis sensors. In addition, there are sub-categories in each of these product types that are based on various specifications, capabilities, capacities, and application requirements.

Discussing load cells specifically, there are different models and configurations depending on the use case, the amount of force measurement or weighing requirements for a particular load, dimensions, and even test environment considerations. No matter what our customers need, we have standard and custom load cells up to the task. In our 101 series, we are highlighting the innovative miniature load cell sub-category of Interface S-Type Load Cells.

What Is an S-Type Load Cell and What Is It Used For?

S-type load cells, sometimes called s-beam, gets its nomenclature from the “S” looking model of the load cell. It is shaped this way because it is designed to measure well-controlled tension and compression forces. There are preferred by engineers and testing labs for the precision, size, material, and ability to fit in limited spaces. They are often used for weighing, in test machines as well as product designs for ongoing performance measurement by OEMs.

An s-type load cell will often be used within a system designed to stress test products in a controlled environment for fatigue and product testing to measure the way the product stands up to force over long periods of time. The benefit of Interface S-Type Load Cells is that they are very cost-effective, highly accurate, easy to mount, and offer flexibility because it can be used universally for tension and compression testing. They are also smaller than typical load cells, providing major benefits when there are limitations in space or for smaller test product dimensions.

Interface has a wide range of specialized miniature s-type load cells including sealed, micro-size, fatigue-rated, high-temperature ratings, low height, overload protected and intrinsically safe to meet all types of testing protocols and plans. You can see all the s-type models here.

An s-type load cell is generally used with eyebolts or rod-ends when used in tension and this can cause binding or the associated hardware to unthread. These uniquely designed load cells should not be used when weighing an object that can sway or rotate. Additionally, an s-type load cell is not recommended when the load cell will be used for both tension and compression, where accuracy in compression is critical. In this case we’d recommend a shear type of load cell.

S-Type Load Cell Applications

Prosthetics Load and FatigueProsthetic Load and Fatigue Testing

Prosthetic limbs must be tested for extreme loading that can occur during falls, accidents, and sports movements. Fatigue testing of prosthetic components determines the expected lifespan of the components under normal usage. Interface suggested a static load test apparatus using SSMF Fatigue Rated S-Type Load Cell attached to hydraulic actuators to apply and measure loads. The fatigue testing machine uses SSMF Fatigue Rated S-type Load Cell to apply and measure cyclic loads. During the fatigue test, the actuator repeatedly applies and removes the force to simulate activity such as walking. Tilt tables may also be used to apply forces at various angles to simulate the heel-to-toe movement of walking or running. Using this solution, engineers can determine whether prosthetic materials and designs will withstand the rigors of daily use and occasional high load situations. Read more here.

Furniture FatigueFurniture Fatigue Cycle Testing

To meet safety protocols in relation to the manufacturing of various furniture products, fatigue testing, shock testing, and proof testing must be rigorously performed before diffusion into the marketplace. Force testing simulations on furniture products are critical in determining the posted max loads to protect manufacturers from liability due to damages that might result from the misuse of those products and overloading. Using an Interface Model SSMF Fatigue Rated S-Type Load Cell along with Interface Model 9890 Strain Gage, Load Cell, & mV/V Indicator provides a solution that measures the force being applied in fatigue cycle testing of a furniture product, in this case testing the rocking mechanism in an office chair. Unlike other similar load cells, the Model SSMF is fatigue rated making it highly suitable for fatigue testing. No fatigue failure of any fatigue-rated Interface load cell, used within its ratings, has ever been reported. The furniture manufacturer was able to obtain accurate data about the rocking mechanism the office chair as it was fatigue cycled into failure. Adjustments were made to the design to improve the safety and life of the furniture, ensuring product quality and protecting the manufacturer from future liability. Read more here.

Interface S-Type Load Cells are highly effective, accurate and flexible products used for a wide variety of applications needing compression and tension force testing. To learn more about Interface’s S-Type Load Cells, you can also visit here or call us today to speak to an application engineer who can help you select the right product for your next project at 480-948-5555.

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.

The Anatomy of a Load Cell

Have you ever stopped to think about what makes the things we use everyday work? At Interface, our engineers think about what makes up an Interface load cell on the production floor and in our design lab every day.

Whether we are manufacturing a new load cell or speaking to a customer about how it can help solve their test and measurement challenges, we are always thinking about what a load cell can do and how to perfect the process of building one that exceeds all customer expectations in performance, reliability and accuracy.

One thing that people ask us about all the time is, what does it look like inside the pioneering Interface blue load cell? In the photo below, you have a cross-section of a basic load cell identifying each of the components and how it all comes together to provide industries around the globe world-class force measurement solutions.

The first component to understand is the strain gage. This mechanism is embedded in the gage cavity and is a sensor that varies its resistance as it is stretched or compressed. When tension or compression is applied, the strain gage converts force, pressure, and weight into a change that can then be measured in the electrical resistance. You can read more in our recent strain gage 101 blog. Here at Interface, we manufacture our own strain gages in-house to ensure premium quality and accuracy.

The main features of a strain gage are illustrated in the following image:

  1. Grid Lines – strain sensitive pattern
  2. End Loops – provide creep compensation
  3. Solder Pads – used to solder interconnecting wire to the gage
  4. Fiducials – assist with the gage alignment
  5. Backing – insulates and supports foil and bonds the strain gage to the flexure

There are also multiple gage configurations depending on the type of load cell. These include:

  • Linear – measures the strain under bending (used in mini beam load cells)
  • Shear – measures strain under shear force (used in low-profile load cells)
  • Poisson – measures strain under normal stress (used in the Interface 2100 Series Column Load Cells)
  • Chevron – measures strain under torsion (used in the Interface 5400 Series Flange Load Cells)

The next component to understand is the load bearing component of the load cell. It is made up of the hub, diaphragm, outer ring, inner ring and base. This component deflects under load to allow the strain gages to send a signal through the connector to the data acquisition device. Customization can include changing the metal materials used to meet environmental or strength concerns and designing the beam height and thickness to meet certain size and stress considerations.

The mounting ring and connector are also incredibly important to the proper use of a load cell and accurate data collection. The mounting ring is the area in which the load cell is mounted to the test rig to measure force and collect data. It is important to pay attention to mounting instructions because an improperly mounted load cell can cause inaccurate results, as well as damage to the load cell. There are also mounting adapters available to fit a wide variety of test rigs.

The connector is the component that allows the load cell to connect to a data acquisition device. The connector is attached via a wire to the data acquisition device and force data is sent through this device to the user through ethernet or Bluetooth® depending on the load cell and data acquisition device configuration. Interface also sells a wide variety of data acquisition devices.

Load cells have many configurations and capacities. In fact, we have made tens of thousands of them over the years to meet standard, modified and engineered to order specifications. The load cell diagram above represents a popular low profile “pancake” load cell.  There are many other styles including miniature load cells, bending and dual bending beams, column-style, S-beam and load button load cells. However, even as the shapes and uses change, the anatomy remains relatively similar, with these main components acting as the workhorse of the load cell and providing accurate force data to the user.

For more information on Interface and our wide range of load cells, torque transducers and data acquisition devices check out our product categories on our site or download our product literature here.

Interface Mini Load Cells Growing in Product Use and Testing

One of the biggest manufacturing trends over the past decade is the miniaturization of hardware components. Reducing the size and weight of products and the components, while increasing the power of complex technology systems, is growing in use across all industry segments using force measurement in design and production.

The growing trend to utilize sensor technology in miniaturized products has been especially significant in the medical, consumer products, technology and robotics industries. These industries are looking to fit more force and measurement capabilities into a package that is the same size, or in many cases, considerably smaller than previous generations of like products.

To address this expanding trend, Interface Mini™ Load Cells were designed specifically for light touch, light weight, high accuracy, and robust performance to utilize for OEM products and smaller testing applications in confined spaces. Our miniature load cells provide exceedingly accurate measurements, similar to our full-size load cells and utilize our proprietary alloy strain gages. Capacities are available as low as 0.11 lbf / 0.5 N and as high as 100 kN.

These small-scale load cells are engineered and manufactured to provide extremely accurate output data with the same degree of precision performance as our standard load cells. OEM’s must have this sort of precision force technology because many of the devices being made today are minuscule and more complex in comparison to earlier products and testing application use cases.

In the medical device industry, innovative and often small new products are used in various life-saving applications. Any inaccuracy or miscalculation of force can have devastating effects. Take a look at how our Interface LBS Miniature Compression Load Button Load Cell and 9330 High Speed Data Logging Indicator were used to record the force measurements when designing and testing vascular clamp surgical devices. You can also read about the Vascular Clamp application note here.

In our earlier Mini Load Cells 101 blog, we discussed the features and benefits of Mini Load Cells in detail. Today, we are highlighting some of our best-selling and new Mini Load Cell solutions available from Interface.

QS48 TruckSpecial Note: A large variety of our standard miniature load cells are available today through our QS48 e-commerce site for easy online ordering. Click here to order now through our QuickShip program and get your mini’s in as little as 48 hours! If you need something specifically customized, reach out to our expert application engineers who can work with you to design custom miniature load cells that will fit your exact requirements.

INTERFACE MINI™ LOAD CELLS

MB Miniature Beam Load Cell

Model MB is a miniature beam load cell used in medical test machines and a variety of low capacity applications. Performance on this product is +/- 0.03% FS and available capacities are 5 to 250 lbf (22.2 N to 1.11 kN).

Product Features:

  • Proprietary Interface temperature compensated strain gages
  • Performance to 0.03%
  • Low height – 1-inch max
  • Eccentric load compensated
  • ±0.0008% /˚F – max temperature effect on output
  • Low deflection

MBP Overload Protected Miniature Beam Load Cell

Model MBP series load cells provide similar performance to Model MB series with the added safeguard of internal overload protection. This patented overload protection is accomplished via hard stops that are EDM machined into the load cell flexure. This provides greater overload protection (2.5-10lbf ±1000% of full-scale capacity, 100 N ±500% of full-scale capacity), giving the user added protection in more severe applications.

Product Features:

  • Proprietary Interface temperature compensated strain gages
  • 10x overload protection
  • Low height – 1in max
  • 0.0008%F temp. effect on output
  • 5′ Integral Cable (custom lengths available upon request)
  • NIST Traceable Calibration Certificate

WMC Sealed Stainless Steel Miniature Load Cell

Interface Model WMC Stainless Steel Miniature Load Cell is excellent for industrial applications because of its stainless steel, sealed, environmentally protected construction. This product is available in capacities ranging from 5 to 500 lbf (22 to 2200 N).  Submersible versions of this product are available as well.

Product features:

  • Environmentally sealed tension and compression load cell
  • Proprietary Interface temperature compensated strain gages
  • Tension and compression
  • Small Size
  • Stainless Steel Construction
  • Submersible

SSM and SSM2 Sealed S-Type Load Cells

Model SSM is a moderately priced highly-accurate sealed load cell for test machines and other general purpose applications. This product is available in capacities ranging from 50 to 10K lbf (200 N to 50 kN).

Product Features:

  • Proprietary Interface temperature compensated strain gages
  • Environmentally sealed
  • 0.02% non-repeatability
  • 0.0008%/°F (0.0015%/°C) temp. effect on output
  • 0.025% creep
  • Tension and compression

LBM Compression Load Button Load Cell

Model LBM Compression Load Button is very popular.  It is constructed from stainless steel and has a small size. This product is available capacities range from 25 lbf up to 50K lbf.

Product Features:

  • Temperature compensated
  • Integral load button
  • Small diameter
  • Environmentally sealed
  • Stainless steel

LBS Miniature Load Button Load Cell

Model LBS Miniature Compression Load Button is constructed from stainless steel and has a small size. This product is available capacities range from 5 lbf up to 1K lbf (22.2 N to 4.45 kN).

Product Features:

  • Temperature compensated
  • Integral load button
  • Small diameter
  • From 0.12″ height

LWPF1 Press Force Load Washer Load Cell

Model LWPF1 Press Force Load Cell is one of several load washer load cells available from Interface. It features a large thru-hole and short overall height. This product is available in capacities ranging from 2 kN to 100 kN (450 to 22.5K lbf).

Product Features:

  • Short height
  • Large thru hole
  • For press-force monitoring

BPL Pedal Load Cell

BPL Pedal Load CellThe Model BPL is a very LowProfile® load cell is used for measuring force on brake pedals. Interface Model BPL has the lowest sensitivity to off-center loading available and will outperform any competitive model.

Product Features:

  • Lowest nonlinearity and hysteresis of any brake pedal load cell – < 0.05%
  • Ultra-low height
  • Low sensitivity to off-axis loads
  • Mounts directly to pedal with included strap(s)
  • Interchangeable mounting plates
  • For use with gas, brake or clutch pedal
  • Storage case included

There are more than 30 different Interface Mini Load Cells and sensors available, in addition to our ability to provide modified and custom Mini Load Cells solutions. To find the Interface Mini that works for your needs, or to learn more about our expanding lineup of load cells and torque transducers, please visit /products/.

Mini Load Cells 101

With the miniaturization and compact size of many products and technologies used in today’s market, it is critical that sensors are designed to fit all types of applications both big and small. This is especially true in the medical, aerospace, industrial automation, and automotive industries.

Interface customer’s requirements for miniature load cells has rapidly expanded the diversification of load cell products that are “mini” in capacities as low as 0.11 lbf / 0.5 N and as high as 100 kN. Interface Mini Load Cell solutions include miniature beam load cells, miniature sensors, load buttons, load washers, tension force mini load cells, S-type load cells, and sealed stainless steel load cells.

Interface’s mini load cells are used for customers who are looking for smaller cells, or for those designing for light touch or lightweight products. Our miniature load cells provide exceedingly accurate measurements similar to our full-size load cells, all with proprietary alloy strain gages. Mini’s are available standard and can be modified, as well as completely customized depending on the exact requirements of the client’s project or embedding into original equipment. Decreased size should never equal less accurate measurements. Our customers can expect Interface miniature load cells perform with the exact quality and accuracy as all our larger load cells.

To provide you with more insight, here is a quick overview of some of Interface’s most popular mini load cells and their unique capabilities. You can download the full Interface Mini Load Cell brochure here.

Load Buttons

Interface’s load button cells are designed for customers who require the measurement of forces in a very confined space. They are designed to provide the most accuracy in as little space as possible. The smaller LBM or LBS can fulfill the need for force measurements at a very respectable precision level that is enough for most applications. Diameters range from 1 inch to 3 inches, with heights from 0.39 inch to 1.5 inches. The shaped load button has a spherical radius to help confine misaligned loads to the primary axis of the cell.

S-Beam Cells

This line is designed for customers looking for extremely compact load cells that still offer great accuracy. The SM (Super-Mini) series load cells are a low-cost, yet accurate, cell with a straight-through loading design. The SSM (Sealed Super-Mini) series offers the same benefits as the SM series with a rugged S-Cell with a splash-proof cover. Both series give exceptional results in applications that can be designed to operate the cell in tension. Some caution should be exercised when using these cells if they will be compressed to ensure that the loading does not introduce side loads into the cell.

Bending Beam Cell

With Interface’s bending beam cell, the cell is bolted to support through the two mount holes. The cell is designed to concentrate the forces into the area where the gages are mounted on the top and bottom faces of the beam. Our line of bending beam cells also have a splash-proof sealing cover.

Double Bending Beam Cell

The double bending beam cell from Interface is a useful variation on the traditional bending beam. In general, this configuration is much more user-friendly because of its short vertical dimension and compact design. It is especially useful for applications where the cells could easily be damaged by tension/compression overload. The variation is achieved by forming two bending beams into one cell. This allows the loading fixtures to be attached at the threaded holes on the centerline, between the beams, which makes the sensitive axis pass through the cell on a single line of action.

Interface mini load cells can be ordered in different sizes, with a wide range of capacities. Many of the minis can be used in off-the-shelf applications. We are also happy to work with customers to custom design load cells to fit their exact needs for size, weight, and accuracy.

For more information on Interface’s Mini Load Cells, visit our web product page or review our product brochure below for detailed specifications on every product.

Mini Load Cell Brochure_6-Page

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