Interface Datasheet 101

Interface provides detailed specifications for all our products in datasheet format. These comprehensive documents are far more than a summary of a load cell, measuring instrument, or accessory. The information in the Interface datasheets provides essential mechanical and electrical information to help you... selecting the right products for your specific testing and measurement projects and programs.

Consider datasheets as technical guides. Interface's technical product datasheet includes a brief description of product features and benefits, a reference image, performance details, and a dimensional drawing. The characteristics defined in the datasheet help distinguish successful validation from system failure.

TIPP: Interface offers a downloadable datasheet for each standard product. In addition, each product has a clear online page that presents the features and benefits of the respective model, specifications, dimensions, diagrams, and details such as properties, connectors, and wiring (where applicable).

The structure of an interface datasheet

At Interface, we group specifications into four categories to provide a holistic overview of the sensor's performance:

• Functional specifications They describe the intended behavior and task fulfillment of the sensor. They define what the system is designed for – including expected use cases, requirements, and the results of specific tasks.
• Technical Specifications They describe the mechanical and material properties of the product. These include physical dimensions, material composition, technical standards, and the capacities required for successful design and implementation.
• Performance specifications These are the crucial criteria for any metrological application. They define the measurable requirements that a product must meet – such as speed, accuracy, reliability, and efficiency – to achieve your testing objectives.
• Construction specifications They describe the external appearance and physical boundary conditions. They often serve as the primary reference for integration into larger assemblies and frequently refer to dimensioned drawings or STEP files.

The performance section in detail

To understand a datasheet, we use the Interface 1200 LowProfile series as a primary example to illustrate what these technical terms mean in practice.

The 1200 series offers a robust measuring range of 300 lbf to 100K lbf (1,5 kN to 450 kN). If you look at the specifications for the 1220 model in the series datasheet, you will see a list of percentage values. These are the accuracy rules for sensors.

To fully master a datasheet, precise metrological definitions for mechanical and electrical specifications must be followed. Here are the key definitions you need to know, each with a reference for further information:

• Nonlinearity: This specification is important because it affects measurement accuracy across the entire measuring range – not just at full load. Lower nonlinearity values ​​indicate a more accurate and precise load cell. REF: Nonlinearity 101
• Hysteresis: The algebraic difference between the output signal at a given load when decreasing from the maximum load versus increasing from the minimum load. For precision sensors like the 1200 series, this value is kept extremely low, at +/-0,05%, to ensure data integrity throughout a complete test cycle. REF: Hysteresis 101
• Static error band (SEB): This is the maximum total error of the load cell over its entire capacity range, including the combined effects of nonlinearity, hysteresis, and repeatability. It represents the maximum deviation between the actual applied load and the load cell's output signal when the load is applied slowly under stable conditions. With a SEB of ±0,04%, the total static error is tightly controlled within this window. REF: What is the static error band output signal?
• Non-repeatability: The maximum difference between initial values ​​under repeated loads and identical conditions. If you apply the exact same load five times under the exact same conditions, how much will the reading vary? The 1220 model of the 1200 series offers a non-repeatability of +/-0,01%, ensuring consistent data acquisition over time. REF: Webinar Summary: Specifications Demystified
• Creep: The signal change that occurs over time under a constant load. This is a logarithmic effect that is symmetrical with load removal. REF: Creep 101
• Eccentric and lateral load sensitivity: An eccentric load refers to forces that act parallel to, but not concentric with, the principal axis and generate moment loads. A lateral load refers to forces applied at a 90-degree angle to the principal axis. The sensitivity is expressed as a percentage of the applied force. REF: Lateral load sensitivity 101

Understanding environmental and electrical specifications

A force transducer is an electrical transducer, which means it is sensitive to its environment.

Temperature influences

Each datasheet includes a compensated temperature range. For the 1200 series, this is typically between 15°F and 115°F (approximately -9°C to 46°C). Within this range, the internal strain gauges are specifically designed to compensate for thermal expansion or contraction. If you operate outside this range (but within the operating range of -65°F to 200°F / approximately -54°C to 93°C), the sensor will still function, but you must account for thermal drift. This is the slight change in zero point or output signal due to temperature variations. REF: Understanding temperature compensation in load cells

Nominal output signal (mV/V)

This is the sensor's signal strength. For many models in the 1200 series, this value is standardized to 2,0 mV/V for aluminum springs or 4,0 mV/V for steel alloy springs. This standardization is a great advantage for engineers because it allows for interchangeability. If you replace a 5.000 lbf load cell with a 50.000 lbf load cell of the same model, the meter's gain settings often don't need to be fundamentally changed—saving time in the lab. REF: Nominal output signal of sensors in millivolts per volt

Mechanical integration

The data sheet also contains safe overload and deflection values. safe overload The maximum load is typically specified as 150% of the rated load. This is your safety net. If this value is exceeded, the sensor's internal structure (the spring) can be permanently deformed. Deflection at nominal output signal This indicates how much the sensor physically moves (compresses or stretches) under full load. For the 1220 model, this value is only 0,002 inches (approximately 0,05 mm). Low deflection is crucial for high-frequency testing or applications requiring high system rigidity.

Six expert tips for optimal use of the interface datasheet

#1 – Capacity selection: Capacitance is a critical balance between achieving a high nominal output signal (signal-to-noise ratio) and maintaining structural integrity. Choosing too low a capacity not only carries the risk of a permanent shift in the zero point. (immediate damage); it increases the risk of premature failure due to exceeding the sensor's fatigue life.

#2 – The fatigue factor: Standard load cells are typically designed for several hundred thousand load cycles. If your application involves millions of load cycles, you must use a fatigue-tested load cell. Fatigue-tested load cells are rated for 100 million fully reversed load cycles. For standard load cells in single-load mode (compression only or tension only), the risk can be reduced by staying at 30–50% of the capacity.

#3 – The overall system perspective: Accuracy is a system-wide attribute. Ambient electrical noise and unshielded cables are common causes of signal degradation. Furthermore, the quality of the power supply is critical. Any noise in the supply voltage is directly reflected in your measurement signal.

#4 – The rule for thermal stabilization: To ensure accuracy in different environments, Allow the entire system – including all cables and devices – to heat up to the test temperature without applying force.This allows you to observe the thermal response and ensure that mechanical connections are stabilized before recording data.

#5 – Calibration adjustment: Adapt your calibration to the testing procedure. If you are only testing in the pressure range, a pure pressure calibration is sufficient. However, ensure that dead weights are used for the lowest traceable measurement uncertainty..

#6 – Complete Systems: If you purchase sensors and measuring instruments together, You should always choose a system calibration to ensure that all components work together harmoniously., and to avoid performance errors before the equipment reaches the laboratory.

Learn more from our experts in this webinar: