Correct Method to Perform Tensile Test by Pacorr

A tensile test measures how a material behaves when it is pulled until it stretches, deforms or breaks. It can determine tensile strength, elongation, yield behaviour and breaking force. However, reliable results depend on proper specimen preparation, machine settings and alignment.

Select the Applicable Testing Standard
The test method should be selected according to the material and the required specification. Common standards include:

• ASTM D638 or ISO 527 for rigid plastics
• ASTM D882 for thin plastic films
• ASTM D412 or ISO 37 for rubber
• ASTM E8/E8M for metallic materials

Each standard defines specimen dimensions, gauge length, conditioning requirements and testing speed. These instructions should be followed instead of applying one common setting to every material.

Prepare and Condition the Specimen
Cut the specimen to the dimensions stated in the applicable standard. Its edges should be smooth and free from cuts, notches or manufacturing damage that could cause premature failure.

Measure the width and thickness at the specified locations using a suitable measuring instrument. If environmental conditions affect the material, condition the specimen at the required temperature and relative humidity before testing.

Check the Tensile Testing Machine
Before starting the test, confirm that:

• The load cell is calibrated and suitable for the expected force.
• The correct grips are installed for the specimen.
• The crosshead returns to its starting position properly.
• The force and extension readings are set to zero.
• Safety guards and the emergency stop are functional.

Selecting an oversized load cell for a low-force specimen may reduce measurement sensitivity.

Mount the Specimen Correctly
Place the sample centrally between the upper and lower grips. Both ends must be held evenly without twisting or bending the specimen.

Incorrect alignment creates uneven stress and can cause the sample to break near the grip. The gripping pressure should prevent slippage without crushing or damaging the test material.

Set the initial grip separation or gauge length according to the selected standard. An extensometer should be used when accurate strain or modulus measurement is required.

Set the Test Speed and Begin Testing
Enter the crosshead speed specified by the relevant standard. The speed can significantly influence tensile strength and elongation results, especially in plastics, rubber and films.

Start the test and observe the specimen throughout the procedure. The machine records the applied force and extension until the sample breaks or the required endpoint is reached.

Validate and Report the Results
Check whether the break occurred within the acceptable gauge area. A result may need to be rejected if the specimen slips, breaks inside the grip or fails because of visible preparation damage.

Test the required number of specimens and report:

• Maximum tensile force
• Tensile strength
• Elongation at break
• Yield strength, where applicable
• Specimen dimensions
• Test speed and gauge length
• Conditioning and test environment
• Failure location and observations

A properly operated tensile testing machine helps manufacturers compare materials, control production quality and investigate unexpected product failures. Pacorr Testing Instruments provides tensile testing solutions for plastics, films, rubber, textiles, packaging materials and other industrial applications.

For product details or technical assistance, contact Pacorr at +91-8882149230 or info@pacorr.com.