Automatic Contacting Extensometer

The need for increased specimen throughput has created a demand for faster, more reliable and more accurate materials testing routines. The AutoX750 automatic contacting extensometer fulfills this demand and enhances the productivity of testing laboratories by allowing them to take advantage of automatic gauge length positioning and attachment to the test specimen. By removing these manual, tedious, and time consuming steps, lab operators can enjoy a simplified testing routine while improving throughput. Reducing the inconsistencies in how a traditional clip-on extensometer is attached greatly improves the repeatability and reproducibility of critical test results.

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AutoX750 Testing Plastics

Principle of Operation

The AutoX750 is automatically controlled through a USB interface and Instron 3300, 5500, and 5900 Series machines with Bluehill® Universal software. The software provides an easy-to-use setup dialog that facilitates opening and closing the arms, setting the reference arm position, and setting the gauge length.

The measuring arms are motor driven and will automatically move to ensure that the vertical position and gauge length are always correct. Prior to the start of a test, the motor will automatically disengage from the measuring arms, allowing the arms to freely travel with the specimen. Additionally, the measuring arms are counterbalanced and operate on a nearly frictionless linear guidance system, making them virtually weightless and removing any influence on the material’s properties.

Application Range

  • Tensile testing for metals, composites, plastics, and elastomers; flexure testing for plastics
  • Specimen shapes: strip, round, hexagonal, and flat
  • Conforms to the most rigorous testing standards, including ISO 527-2 and ASTM D638 for plastics and ISO 6892-1 and ASTM E8 for metals

AutoX750 Automatic Contacting Extensometer


High Travel

With 750 mm of travel, the AutoX750 uses an optical measurement system that has a higher resolution and better accuracy than linear displacement or strain gauge transducers.


Counterbalance Technology

Tried and tested counterbalance technology provides virtually friction-less movement along the full vertical travel, preventing the weight of a clip-on from affecting your results.


Auto-Attaching Arms

Designed to reduce set up time, the rugged, self-centering arms automatically attach to the specimen and can remain attached through failure for most materials.


Interchangeable Knife Edges

Knife edges can be swapped out and clamping forces adjusted to accommodate a variety of materials.


ENDLESS Applications

The AutoX750 can be used to determine a variety of calculations including modulus, offset yield, plastic elongation to failure (non-proportional), and r and n values for sheet metals. Its high accuracy and travel make it an ideal extensometer for a variety of materials including metals, plastics, and composites.

For Simultaneous Axial and Transverse Strain Measurement



The AutoXBiax – built with the same high accuracy optical measurement system as the AutoX750 - is an automated, high precision measurement device that measures both axial and transverse strain simultaneously. Compatible with the 3382A and 5900 Series systems, the AutoXBiax is specifically designed to measure the plastic strain ratio (r-value) for steel and exceeds current standards, including ISO 10113, ASTM E517, and JIS Z 2254.

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An Inside Look at How the AutoX Works

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AutoX750 Data Sheet