How to use Elmendorf tear tester

Posted by Cora on March 22nd, 2018

Elmendorf tear definition

Elmendorf tear tester is a computer controlled instrument attached to a Pendulum which measures the tearing strength of various textiles like fabrics and other materials like plastics, papers and board. The tearing tester is further enhanced and supported by the attached computer which is quite easy to use. This tear tester will show its best performance when a Elmendorf tear testing is done

Elmendorf tear strength testing is used to determine the force which is required to continue the tearing of an initial cut of either of above-mentioned materials.

This tester was designed to test the dynamic resistance of materials by subjecting them to strong shearing load and damage caused to the textile material by sharp and heavy objects. Later, the test was adopted to test other materials too.

Knowing what the machine does will benefit only when it is known how to use it to test all the materials. Let's look at few basic features of Elmendorf tear strength tester.

Pneumatic clamps

A pneumatic tester gripping system provides a sufficient clamping pressure to avoid any slipping or displacement of the specimen under test. It is a simple two-button operation and the repeatable system ensures a perfect reproducibility of the conditions required for the experiment.

Pendulum method

The tearing effect on the material is measured by Pendulum method. Under this method, Elmendorf tear tester manual and Elmendorf tear test units are most commonly used machines.

This Pendulum is a tool-less hardware which provides an ability to interchange testing weights for different testing options.

It is similar to tongue tearing method and is commonly used upon woven fabrics and is not suitable for woven elastic methods, knitted fabrics or any other material which has a possibility of tearing transfer.

GUI touchscreen interface 

This machine is made very simple to use by an attached large colored graphic touch panel without any computer or software. This large graphical user interface screen allows a full control over the instrument.

The screen can be calibrated with the Pendulum by its touchscreen panel.

Let's look at Elmendorf tear tester procedure of testing a textile material - 

1. Prepare the sample for testing 

Two sample specimens can be prepared based on the requirement, either a warp sample or a wept sample.

Warp and weft are the two directions based on how the sample is placed for the testing. Make sure to place the shorter of the specimen parallel to the warp or weft to ensure that the tear is made along the incision.

After the sample is cut, put it under constant temperature and humidity before testing the sample piece.

2. Prepare the instrument for testing 

Calibrate the equipment, check the Pendulum quality so as to make sure that the test results of Elmendorf tear tester are within the range of 15% to 85% of the corresponding scale.

With the calibration set to zero, the Pendulum should rise to it's starting position and the pointer should also point to zero.

3. Attach the sample specimen to the clamps 

Sandwich the specimen between the clamps and make sure that the sample is placed in the center with its lower side towards the base of the head of the clamp and upper side parallel to the top the clamp head.

Make the incision with a shearing device in the middle of the opposite side of the groove of the sample according to the rules, leaving a length of about 43 mm to be torn.

4. Measuring the performance of the tester 

Start the equipment and let go of the Pendulum to start the tearing. Hold the Pendulum when it reaches the higher position to avoid any damage to the position of the pointer and then read out the data pointed by the pointer. Elmendorf tear test results falls within the range of 15% to 85% of the used scale.

The mean tear strength of the sample is calculated according to the observations of the longitudinal and latitude direction.

Conditions to look after while testing of the fabric 

Care should be taken to see the tear is in the direction of the force and whether the yarn is slipping of the fabric rather than being torn. If the fabric slips from the clamps, the results need to be removed.