FUTEK’s calibration department performs testing with a focus on expediency, reliability and rigorous attention to detail.
 

Our calibration services include:

  •  Full-system calibration for sensors with FUTEK and non-FUTEK digital displays, amplifiers and USB solutions
  •  Available support for non-FUTEK sensors, and engineering services for custom non-FUTEK fixtures
  •  Full NIST and A2LA traceable calibration services of load cells, torque sensors, multi-axis force sensors, pressure sensors, and instruments
  •  Dead weight force sensor calibration capabilities ranging from 1mg to 10K lbs
  •  Hydraulic load cell calibration up to 400,000 lbs
  •  Advanced calibration lab capabilities that can support complex custom sensor platforms
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Our unique customer benefits include:

  •  Fast turnaround time of up to one business week upon arrival
  •  Expedited services at no extra cost
  •  Convenient online order placement
  •  Addition of new brand new products to existing calibration orders
  •  Calibration calculator to track product recalibration needs
  •  Supply of spare cable and parts if needed

Examples of the calibration certificates we offer:

When you receive your calibration certificate, do not discard it because it contains pertinent information relating to the sensor(s) you purchased.
 

Our wide range of calibrations

We offer our customers the unique ability to select the exact calibration direction outlined per their application's requirements, including:

Sensors will be calibrated in tension
Sensors will be calibrated in compression
Sensors will be calibrated in both tension and compression
Sensors will be calibrated at pressure
 
Sensors will be calibrated in clockwise direction
Sensors will be calibrated in counter-clockwise direction
Sensors will be calibrated in both clockwise and counter-clockwise direction
Sensors will be calibrated in a vacuum
 

Due for recalibration?

Because our products are used in critical applications that require exact specifications, we have created a recalibration program that continuously supports our customers needs for verification and alignment. We also offer recalibration services to customers who have purchased test and measurement products from the following manufacturers:

  •  Honeywell/Sensotec/Lebow
  •  Interfaceforce
  •  Omega
  •  Transducer Techniques
  •  HBM
  •  Himmelstein
  •  Strainsert
 

General calibration services frequently asked questions (FAQ)

Why is it important to calibrate load cell and torque sensors?

Load Cell Calibration Service is an adjustment or set of corrections that are performed on a load cell, or instrument (amplifier), to make that the sensor operates as accurately, or error-free, as possible. Every sensor is prone to measurement errors. These structural uncertainties are simply the algebraic difference between the value indicated by the sensor output versus the actual value of the measured variable, or, known reference loads, in order to generate the load cell calibration curve.

Every sensor is prone to measurement errors. These structural uncertainties are the simply algebraic difference between the value that is indicated by the sensor output versus the actual value of the measured variable, or known reference loads. Measurement errors can be caused by many factors:

  • Zero offset (or zero balance) — An offset means that the sensor output at zero load (true zero) is higher or lower than the ideal output. Additionally, zero stability relates to the degree to which the transducer maintains its zero balance with all environmental conditions and other variables remaining constant.
  • Linearity (or non-linearity) — Few force sensors have a completely linear characteristic curve, meaning that the output sensitivity (slope) changes at a different rate throughout the measurement range. Some are linear enough over the desired range and does not deviate from the straight line (theoretical), but some sensors require more complex calculations to linearize the output. So, load cell non-linearity is the maximum deviation of the actual calibration curve from an ideal straight line drawn between the no-load and rated load outputs, expressed as a percentage of the rated output.
  • Hysteresis — The maximum difference between transducer output readings for the same applied load; one reading is obtained by increasing the load from zero and the other by decreasing the load from the rated output. It usually measured at half rated output and expressed as a percentage of the rated output. Measurements should be taken as rapidly as possible to minimize creep.
  • Repeatability (or non-repeatability) — The maximum difference between transducer output readings for repeated loadings under identical loading and environmental conditions. It translates into the load cell's ability to maintain consistent output when identical loads are repeatedly applied.
  • Temperature Shift Span and Zero — The change in output and zero balance, respectively, due to a change in transducer temperature.

 

Figure 1: Load Cell Calibration Curve.

Each force sensor has a "characteristic curve" or a "calibration curve", which defines the sensor's response to an input. During a regular calibration using the load cell calibration machine, we check the sensor's zero offset and linearity by comparing the sensor output under reference weights and adjusting the sensor response to an ideal linear output. We also check hysteresis, repeatability and temperature shift when customers request it for some critical force measurement applications.

For more information about calibration, please refer to our Force Sensor Calibration FAQ Page.

If you have further questions about calibration terms and definitions, please refer to our Force Sensor Calibration Terms Glossary.

How often should a load cell be recalibrated?

As load cells are exposed to continuous usage, aging, output drift, overload, improper handling, FUTEK highly recommends a yearly recalibration interval. Frequent recalibration helps confirm whether the sensor maintained its accuracy over time and provides a load cell recalibration certificate to show the sensor still meets specifications.

However, when the sensor is used in critical applications and harsh environments, load cells may require even more frequent calibrations. Please consult with our Technical Support team, who will help you evaluate the most economical calibration service interval for your force sensor.

What is a system calibration (sensor plus amplifier/instrument)?

A system calibration provides the signature of the performance of the sensor and instrument together ("calibration curve") and ensures that the combination of the results meet specifications. A force measurement system usually encompasses the force sensor, instrument or signal conditioner (amplifier electronics), cabling, and connectors. Full system calibration ensures that the whole system is performing accurately as expected.

Check out below a video on the "Benefits of System Calibration":

 

 

Choosing complete system calibration allows you to start using your force measurement solution out of the box. A system calibration creates a plug & play solution where all connectors, cables, and instrument settings are taken care of.

As an A2LA certified calibration lab, FUTEK offers full system calibration for sensors with digital displays, amplifiers, and/or USB solutions, and use calibration procedures in compliance with ISO 17025 standards. FUTEK's certification includes accreditation to ANSI/NCSL Z540-1.

What are the different types of load cell calibration procedures?

One-point calibration

  • One-point calibration is the simplest type of calibration and it is recommended for applications that only require accurate measurement at a single load or torque. If the force sensor is known to be linear, repeatable, and has the correct slope over the desired measurement range, a one-point calibration can be applied to adjust the zero offset error (zero balance).
  • A one-point force sensor calibration also helps to verify "output drift" in order to correct any deterioration in sensor performance over time.

Two-point calibration

  • A two-point calibration is a little more intricate and more precise than a one-point calibration. In a two-point calibration, the sensor offset is adjusted at two different output values, resulting in a reasonably accurate straight line across the entire force measurement scale. It is typically recommended that the two points used are zero and the full scale (rated output).
  • Load cell and torque sensors are known to be reasonably linear over the measurement range (or rated output), thus a two-point calibration is often recommended, given that a two-point calibration essentially re-scales the output by correcting both the slope (load cell sensitivity) and offset (zero balance) errors.
  • With the new zero offset and slope (load cell sensitivity), one can determine the linear equation that characterizes the sensor output (Vout=Sensitivity*Load + Zero_Offset).

Five-points calibration (multi-point curve fitting)

  • Some critical applications require a high degree of accuracy over a very specific measurement range of the force sensor. In these cases, a five-point load cell calibration and curve fitting are required to characterize the calibration curve and achieve measurement output over the specified output range.
  • Normally, a five-point calibration is performed by taking the output at 0%, 20%, 40% 60%, 80%, 100% of the required measurement range:
    • 0%: Zero offset adjustment (or zero balance);
    • 20%, 40%, 60%, 80%: Linearity adjustments;
    • 100%: Span or slope adjustment (sensitivity).
  • In the five-point force sensor calibration process, the output readings are taken in the upscale and downscale values to determine the repeatability and hysteresis of the force measurement system (sensor + signal conditioner).

As most of the force sensors are paired with a readout display or signal conditioner to form a turnkey force measurement system, the instrumentation should always be hooked up with the sensor and be calibrated together as a system using standard equipements of the torque sensor calibration lab. That said, consider for example a 50 lbs LSB205 Miniature S-beam Load cell paired with an IAA200 4-20mA Current output amplifier and a 10ft long cable. When requested by the customer, the five-point output readings would be taken when the sensor is subjected to loads of 0 (no load), 10 lbs, 20 lbs, 30 lbs, 40 lbs and 50 lbs upward scale and downward scale.

% OF FULL SCALE APPLIED LOAD (LBS.) AMPLIFIER OUTPUT (MA)
0% — No Load No Load 4 mA
20% 10 lbs 7.2 mA
40% 20 lbs 10.4 mA
60% 30 lbs 13.6 mA
80% 40 lbs 16.8 mA
100% — Full Scale 50 lbs 20 mA
80% 40 lbs 16.8 mA
60% 30 lbs 13.6 mA
40% 20 lbs 10.4 mA
20% 10 lbs 7.2 mA
0% — No Load No Load 4 mA

Table 1: Load Cell 5-Points Calibration and Multi-Point fitting.

Depending on the application requirements, this procedure is repeated twice or multiple times. The difference in the outputs is utilized to calculate the non-repeatability (or repeatability) and linearity (accuracy).

We are frequently questioned on how to calibrate a torque wrench. This can be accomplished by utilizing FUTEK’s TDF Torque Sensor as a torque wrench calibration tool to verify the precision of a torque wrench.

 

 

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