A load cell is an instrument that reports force as a number. Strain gauges cemented to a machined element pick up the slight flexing that load produces, bridge circuitry renders that as voltage, and a calibration against known reference weights makes the voltage mean something in pounds.
Where it gets interesting is what "accurate" means once you're comparing two of them. Datasheets rarely offer a single accuracy figure, because there isn't one — there are several distinct ways a sensor can be wrong, they're specified separately, and which of them matters depends entirely on what you're doing with the readings.
Nonlinearity describes how far the output strays from a straight line between zero and capacity. Load cells are not perfectly linear, and the deviation tends to be largest somewhere around mid-range rather than at the ends. If you calibrate at full scale and then work at 40% of capacity, nonlinearity is the error you inherit.
Hysteresis is the gap between the reading you get climbing to a load and the reading you get coming back down to the same load. It exists because the metal doesn't retrace its path exactly. Any test that loads and unloads — which is most of them — runs into it.
Nonrepeatability is the scatter you see applying the identical load several times under identical conditions. It deserves particular attention for a reason worth remembering: unlike some error sources, it cannot be compensated for or calibrated out. A lower number is simply better, permanently.
Zero balance is the residual offset the sensor shows with no load applied, and temperature coefficients tell you how far both the zero and the span wander per degree. Compensation across a stated band is what keeps those in check.
Sensors built for tighter figures on all of these tend to look outwardly similar to ordinary ones. The difference is in machining tolerances, gauge selection and placement, and the compensation work done during manufacture — which is why two load buttons of the same capacity and the same 17-4 PH stainless construction can carry noticeably different accuracy specifications and noticeably different prices. Compression button designs of this kind turn up in materials testing, industrial automation, aerospace and automotive component testing, and any quality-control station where measurements are compared against each other rather than simply observed.
Understanding where a load cell's error actually comes from makes its specifications far more useful than treating them as marketing numbers.
The signal path. A supply voltage — 10 VDC is typical — energises the bridge. Load arrives, the element yields microscopically, and the foil gauges riding on it shift resistance by an amount that tracks the force; what emerges from the bridge is a few thousandths of a volt of imbalance. Because that output is a fraction of whatever you supplied, sensitivity is stated as a ratio in mV/V. Amplification, filtering and digitising follow, and the stored calibration turns the result into force. One consequence worth internalising: the supply voltage in service must match the one used at calibration, or every value you record is scaled by the discrepancy.
Why the numbers aren't perfect. The element is metal being deliberately worked within its elastic range. Metal is very good at this but not flawless. It doesn't respond in a perfectly straight line, it doesn't retrace its own path exactly on unloading, and it doesn't return to precisely the same starting point every single cycle. Those three imperfections are what nonlinearity, hysteresis and nonrepeatability actually measure. Held under sustained load it also creeps slightly as the material accommodates the stress, and it needs time to recover afterward — which is why long holds and rapid re-tests behave differently from single measurements.
Which specification governs your result. This is the practical question. If you calibrate at one point and measure at another, nonlinearity dominates. If your test cycles up and down, hysteresis does. If you're comparing part to part on a production line, nonrepeatability is the figure that decides whether your data can distinguish a good part from a marginal one. If measurements are held for minutes at a time, creep and temperature drift move to the front. Reading a datasheet well means knowing which of your errors you're actually buying down.
What the installation adds. None of the above helps if the mechanical side is wrong. A compression button reads what its loading face experiences, so the pressing surface has to be flat, hard, and large enough to cover the loading area properly — manufacturers often publish a minimum mating diameter for exactly this reason. Load arriving off-centre is only partly counted. Mounting hardware should be fully engaged and correctly preloaded, since a joint that isn't properly clamped will move under cyclic loading and take your readings with it.
Calibration defines direction. The relationship between force and signal is established by loading the sensor with references of known value and logging what comes out. Push and pull do not share a load path, so whichever direction was used during that exercise is the only one described by the resulting certificate.
Choosing between load cells that look alike on the shelf usually comes down to reading their specification sheets properly and knowing which line items your application will actually feel. Our application engineers do this comparison daily and are happy to do it with you.
Work out which error matters to you first. Before comparing any two sensors, decide what your measurement is for. Comparing parts against one another? Nonrepeatability governs. Cycling load up and down? Hysteresis. Working well away from your calibration point? Nonlinearity. Holding load for extended periods, or working in a shop that warms up through the day? Creep and the temperature coefficients. A sensor that's excellent on the specification you don't need is not the better sensor for you.
Then decide what precision is worth. Tighter accuracy figures come from tighter manufacturing, and they cost accordingly. That premium is well spent when your measurement feeds a pass/fail decision, supports a quality record, or has to be defended to a customer or auditor. It's harder to justify when you're monitoring a process for gross changes and a couple of percent either way wouldn't alter what you do next.
Size the capacity to where you actually work. Accuracy specifications are percentages of rated output, so the absolute error scales with the sensor's capacity, not with the load you happen to be applying. A cell rated far above your working force spends its accuracy budget on range you never use. Choose so your normal measurements sit well inside the range, then verify your realistic worst case against the safe overload figure.
Prepare the mechanical side to match. Any published minimum mating surface diameter is a requirement rather than a suggestion — undersize it and the load concentrates instead of distributing as designed. The pressing face wants to be hard, flat and stable; the mounting surface flat and stiff enough not to deform at peak load; the fasteners properly engaged and torqued to specification rather than beyond it.
Consider how the load arrives and how fast. Can you keep it centred on the button every cycle? Is the force applied gradually, or does it slam on? Fast events reward stiff, low-deflection designs, but only if your conditioner and acquisition rate can follow them — the slowest link in the chain sets your real response.
Then the practical items. Which way does the load act? Compression units are certified in compression, so a pulling component is something to raise at quotation. What will the temperature do, and can you translate that into an error figure from the published coefficients rather than shrugging at it? And what sits on the other end of the cable? That might be nothing more than a regulated supply, or an amplifier signal conditioner module feeding your acquisition system, or a digital display running setpoints and logging on its own. Wherever units get shuffled between instruments, Cal-Teds plug and play pays for itself.
Tell us what you're measuring, how the result gets used, and what the sensor mounts to, and we'll help you decide where precision is worth paying for and where it isn't. Stock capacities go out the following day, and there is an academic rate for teaching and research buyers.
LBM Series Load Cell Applications.
The Transducer Techniques LBM Series low-profile load button load cell, featuring a slightly convex loading diameter for accurate load distribution and eight threaded mounting holes on the bottom surface, offer a wide range of capacities from 0 to 50 lbs. to 0 to 10,000 lbs.
- Industrial Automation: LBM Series load cells are commonly used in industrial automation systems to monitor robotic end-effector forces, ensure precise material handling, and control manufacturing processes to maintain product quality and safety.
- Material Testing: These load cells play a crucial role in material testing applications, including tensile, compression, and flexural tests conducted on a wide range of materials, from metals and plastics to ceramics and composites. They provide accurate data for research, quality control, and material characterization.
- Aerospace and Defense: The aerospace and defense sectors rely on these load cells for structural testing of aircraft components, weapon systems testing, and ground equipment testing. Their high precision and durability contribute to the safety and reliability of critical equipment.
- Automotive Testing: Automotive manufacturers use LBM Series load cells for a range of testing applications, including crash testing, suspension component testing, and brake system testing. These load cells assist in evaluating vehicle safety and performance.
- Heavy Machinery and Construction: In construction and heavy machinery applications, LBM Series load cells monitor loads on cranes, hoists, and lifting equipment, ensuring safe and efficient operations on construction sites and in material handling facilities.
- Manufacturing Quality Control: Manufacturers across industries, including electronics, consumer goods, and industrial equipment, employ LBM Series load cells for quality control processes. These load cells verify that products meet specific force or weight requirements during production.
- Research and Development: Researchers and engineers use LBM Series load cells for a wide range of R&D purposes, including product development, material testing, and prototype evaluation. They provide accurate force measurement data for research initiatives.
- Educational and Training Laboratories: Educational institutions incorporate LBM Series load cells into engineering and physics laboratories to teach students about force measurement principles and conduct experiments related to mechanics and materials science.
- Custom Machinery and Equipment: Manufacturers often integrate LBM Series load cells into custom machinery and equipment designed for specialized testing and manufacturing processes that require precise force measurement.
The Transducer Techniques LBM Series low-profile load button load cells, manufactured from heat-treated 17-4 PH stainless steel and featuring a convex loading diameter, offer exceptional durability and accuracy, making them indispensable tools in a diverse range of industries and applications where reliable force measurement is essential for safety, quality, and performance.
Frequently Asked Questions
What makes the LBM the most accurate load button we offer?
Its specifications are tighter across the board than our other load button series. Nonlinearity is 0.15% of rated output rather than 0.25%, hysteresis is 0.1% rather than 0.25%, nonrepeatability is 0.05% rather than 0.1%, and zero drift with temperature is 0.005% of rated output per °F rather than 0.01%. That's a better figure on every accuracy line item, not a trade of one against another — which is what makes the LBM the one to specify when the measurement has to hold up to scrutiny.
What capacities does the LBM Series come in?
Ten models: 50, 100, 200, 500, 1,000, 2,000, 2,500, 5,000, 8,000, and 10,000 lb, all at the same price. Because accuracy specifications are percentages of rated output, that single price across the range means you can pick purely on the force you actually work at, without any temptation to over-specify capacity for budget reasons and quietly give up absolute accuracy in the process.
Why does the LBM need a mating surface at least 2 inches in diameter?
The loading diameter is slightly convex so that force spreads predictably into the sensing element rather than concentrating at a point. That distribution only works if the surface pressing on it is flat and large enough to fully engage the loading area — hence the published minimum of 2 inches diameter. Undersize it and load concentrates where it wasn't meant to, which is one of the few ways to lose the accuracy advantage you paid for before the sensor has done anything wrong.
What are the eight threaded mounting holes for?
They're on the bottom face and let you fasten the cell down securely from underneath, with eight points spreading the clamping load evenly around the base rather than concentrating it at a few spots. Even clamping matters more on a precision sensor than on a general-purpose one, because uneven clamping is itself a source of the offsets and inconsistency that tighter specifications are meant to eliminate.
What does the LBM's 0.05% nonrepeatability figure actually buy me?
Consistency you can build a decision on. Nonrepeatability describes how much the reading scatters when you apply the same load again under the same conditions — and unlike some error sources, it can't be calibrated or compensated away. At 0.05% of rated output, half the figure of our standard load buttons, the LBM can resolve smaller genuine differences between parts before the sensor's own scatter swamps them. For production comparison and quality records, this is usually the specification that matters most.
Is the LBM compression only?
Yes. It's a compression load button, calibrated in compression, with the convex loading diameter designed for force arriving downward onto the button. If your application involves any tension component, raise it with us before ordering rather than after — the load path differs between directions and a compression calibration documents compression behaviour alone.
What is the LBM's deflection, and why is it the same across all capacities?
0.002 inches at rated output, consistent across the range. Holding deflection constant means a 10,000 lb LBM moves no further under its full load than a 50 lb LBM does under its own, so your fixture geometry and clearances behave the same way regardless of which capacity you fit. That predictability is useful if you may change capacity partway through a project, and the low figure itself indicates a stiff element that settles quickly rather than continuing to move as load is applied.
How does temperature affect an LBM reading?
The LBM is compensated from 60° to 160°F, with a safe operating range of −65° to 200°F. Within the compensated band, output drifts 0.005% of load per °F and the zero drifts 0.005% of rated output per °F. That zero coefficient is half what our standard load buttons carry, which matters on long runs and in shops that warm through the day — zero drift is usually what moves first and it's the harder of the two to notice while it's happening.
What is the LBM made from?
Heat-treated 17-4 PH stainless steel with bonded foil strain gauges. 17-4 PH is a precipitation-hardening stainless, meaning controlled heat treatment forms fine particles through the metal that raise its strength several times over standard grades without introducing the distortion that would spoil a precision component. Dimensional stability of that kind is part of what makes the tighter accuracy figures achievable and repeatable over the sensor's life.
Can I get the LBM with the plug-and-play TEDS option?
Yes, OPT-TEDS is available and adds IEEE 1451.4 smart connector capability, storing the unit's calibration data at the connector so a compatible instrument reads and applies it automatically. On a precision sensor this is more than a convenience — a mistyped calibration value can silently cost you more accuracy than the difference between a standard and a precision load cell, and this removes that opportunity entirely.
Questions From The Field
I bought the LBM for its accuracy but I'm not seeing better results than my old cell.
The most common reason is that something in the installation is contributing more error than the sensor ever did. Work through the mechanical side first: is the pressing surface flat, hard, and at least 2 inches in diameter; is the load genuinely centred on the button; is the mounting surface flat and stiff enough not to deflect at your peak load; are all eight fasteners evenly torqued? Then check the electrical side — excitation matching your calibration, and correct calibration values entered. A precision sensor doesn't improve a poor installation, it just measures it faithfully.
Which of the LBM's accuracy specs should I care about for my application?
It depends on what you're doing. Comparing part to part on a line, nonrepeatability at 0.05% governs your result. Cycling load up and down through a test, hysteresis at 0.1% is what you'll feel. Working at a force well away from where the system was calibrated, nonlinearity at 0.15% dominates. Holding load for extended periods or working through a temperature swing, the drift coefficients take over. If you tell us how the measurement gets used, we can point at which number will actually limit you.
Should I choose an LBM or one of your other load buttons?
Match the sensor to what the reading is for. If the measurement supports a pass/fail decision, a quality record, or something you'd have to defend to an auditor or a customer, the LBM's tighter figures are worth paying for. If you're monitoring a process for gross change and a couple of percent wouldn't alter what you do next, a standard load button is the sensible spend. Note also that the LBM tops out at 10,000 lb — above that, capacity rather than accuracy makes the decision for you.
My readings drift downward while I hold a steady load on the LBM.
Some of that is expected physics rather than a fault. Under sustained load the sensing element creeps slightly as the material accommodates the stress, and it needs time to recover once unloaded — so back-to-back long holds can read differently from a single one. Separate that from installation causes by holding the same load against a hardened, flat surface with everything properly torqued; if the drift is much larger than the temperature coefficients would predict, look at a soft platen bedding in or a fixture relaxing before you suspect the cell.
My mating surface is smaller than 2 inches. Is that really a problem?
Yes, and it's worth taking seriously. The convex loading diameter is designed to distribute force across a properly sized flat surface; undersize that surface and load concentrates rather than spreading, which changes what the sensing element experiences and can affect both accuracy and, at higher capacities, the sensor itself. Adding a hardened flat platen of adequate diameter between your fixture and the button is usually a straightforward fix and far cheaper than absorbing an unknown error into your data.
Do I need to tighten all eight mounting bolts, and in what order?
Use all eight, and tighten them progressively in a cross or star pattern rather than working around the circle or fully torquing one at a time. Eight evenly loaded fasteners distribute clamping force around the base as the design intends; tightening unevenly pulls the cell down harder on one side, and uneven clamping is exactly the kind of installation error that erodes a precision sensor's advantage. Bring them all to snug first, then up to final torque in stages.
Does the LBM's better accuracy mean I can extend my calibration interval?
No — those are separate things. Accuracy specifications describe how the sensor behaves when it's in calibration; they say nothing about how long it stays there. Calibration interval should follow your quality system, how heavily the sensor is used, and whether it's seen any overload or rough handling, exactly as it would for a standard cell. Annual is a common baseline. If anything, a sensor bought specifically for precision deserves its interval respected rather than stretched.
Can I swap a different LBM capacity into the same fixture?
Mechanically it's usually straightforward, since deflection stays at 0.002 inches across the range and the mounting arrangement is consistent — but check the physical dimensions and bolt pattern for the specific capacity before assuming a drop-in fit. More importantly, update your instrument with the new unit's calibration values. Running a precision sensor against the previous unit's settings produces readings that look entirely plausible and are wrong, which defeats the reason for buying it. The OPT-TEDS option removes that risk if you swap capacities regularly.