Mounting the Model 3448 Self-Supporting, Axial Furnace Extensometer

The following video provides a visual demonstration of mounting the 3448 self-supporting, axial, furnace extensometer to a test specimen.

The model 3448 extensometers are held onto the specimen by light, flexible ceramic fiber cords. These allow the extensometer to support itself on the specimen so that no furnace mounting brackets are required. The side load on the test sample is greatly reduced because of the self-supporting design and light weight of the sensor. Most materials testing furnaces with a side cut-out for an extensometer will readily accept a Model 3448. For induction heating systems, a different ceramic cord placement allows the extensometer to easily pass between the coils.

High purity alumina (min 99.7%) ceramic rods are used with this model. These are available in lengths as required to fit your furnace. A spare set is included with every extensometer. Specify chisel (round and flat specimens), vee chisel (round specimens) or conical contact points (flat specimens) as desired. Most units operate equally well in tension and compression. Thus tensile, compression and cyclic tests like low cycle fatigue can all be performed with a single unit.

For more information on these and other Epsilon products, please visit our website at www.epsilontech.com.

What's New at Epsilon Technology

3590VHR Extensometer Calibrator and Epsilon’s Laser Interferometer System

We are very excited about the introduction of the 3590VHR very high resolution calibrator system, and the interferometer system. The laser interferometer greatly increases the accuracy of much of what we measure. This allows calibration of extensometer calibrators as well as extensometers. With an accuracy of 0.5 parts per million, it very closely approaches the measurement accuracy of national standards.
The 3590VHR system allows us to accurately and reliably calibrate our calibrator systems in their entirety. We do not rely only on the calibration of the sensor – the full system is calibrated traceable to NPL (the UK standards organization ), as needed to comply with ASTM and ISO standards. The 3590VHR meets the very stringent requirements of both ASTM E83 and ISO 9513 to the following specifications:

• Scale resolution: 20 nm (0.8 microinches)
• Scale Accuracy:
• ±0.19 microns (±7.5 microinches) over any 0.12 mm (0.00475 inch) range
• Meets ASTM E83 Class B-1 for a 6 mm gage length and greater extensometers and ISO 9513 Class 0,5 over the full measuring range of the calibrator.

Model 3542 Axial Extensometer

The Model 3542 general purpose, axial extensometer was updated in May of 2009 with a new cross-flexure design, and with that it brought some additional changes:

• The new flexure design allows us to use arms that are approximately 2 inches (about 50 mm) shorter than the previous model for higher measuring range units. We can go even shorter than that, so if you have a special requirement, please let us know.
• The 2 inch/50 mm gauge length version with 50% measuring range weigh less than 80 grams. The combination of size, weight and robustness is perfectly suited for testing all types of engineering materials.
• These units incorporate a new strain relief design that improves performance, and better prevents cable wear.

The new version of the Model 3542 brings the same great reliability and even better performance than previous generations. The updated version of our 3542 still has access to all the accessories of previous versions including:

• A variety of contact knife edge styles. Customers will find the standard knife edges well suited for most of their testing needs, but the 3542 provides a variety of contact blade options (link to knife edge options page) that may help improve performance in tests with special requirements.
• Wireforms suitable for use across a wide range of specimen geometries.
• Gage length adapter kits that can be used to convert the 3542 to nearly any gage length. 

Capacitive Probe Redesign
The capacitive probe used on the Model 3555 uncooled, high temperature axial extensometer, Model 3675 uncooled, high temperature transverse extensometer and Model 3641 uncooled, high temperature COD gage was redesigned and introduced at the end of 2009. This is Epsilon’s fourth generation probe design. This redesign resulted in several improvements:

• All probes are verified for use to 540°C.
• Failures of the previous generation probe were analyzed, and the new design addressed each one. As a result the reliability of the probe has been significantly improved. Since full scale introduction in 2010, we have not had a unit returned due to probe failure.

The probe used on the Model 3648 high temperature, capacitive, axial furnace extensometer with ceramic rods was also redesigned to remove the area of greatest failure. This too has resulted in a dramatic increase in the reliability of the model with no unit being returned for probe failure since its introduction.


For more information on these and other Epsilon products, please visit our website at www.epsilontech.com.