Tensile Units Explained

Posted on 31st May 2019

We also briefly explained some of the processes we adhere to when it comes to calibrating certain types of equipment. In this article, we will explore the subject of tensile units and what they calibrate.

What are Tensile Units?

The tensile units we use at CoMech Metrology are also known as tension units, which can measure up to 30kN of force, depending on which machine is used. The units perform compression, resistance, tension and multiple stage tests to load, displacement, height and time configurations while conforming to UKAS ISO 17025.

The tensile units are primarily used on many materials such as rubber, metal, concrete, carbon fibre and much more. Tensile units are particularly favoured for their versatility, as they’re used on items within many industries including rail, aerospace, construction, automotive and surveying. No matter what is being tested, they are always used to make sure the integrity of the item or material conforms to all the relevant and latest standards.

What is Tensile Testing?

Tensile testing is a simple procedure using a tensile machine to verify how an item or material will react when it is pulled apart. The force is applied in tension. There are various types of tensile testing for various materials, including tear resistance, crimp force, bond strength and peel.

Tear resistance testing on a tensile unit is ideal for testing plastic, paper and textile specimens with the objective to create a tear or cut. The force measurement is dependent on an object’s thickness.

Crimp force testing is specifically used testing the mechanical strength of crimp joints. Pull force tests are conducted to ensure the crimp tool’s quality. These tests are most ideal for calibrating crimp tools for the rail industry.

Bonding strength on a tensile machine is a method used to test the strength of the bonding adhesives within the tested object or material.

Peel testing is also known as seal strength testing and is used for testing the strength within certain materials. The object in question is placed inside the tensile unit’s frame to create a pulling motion to separate the specimen.

The Tests Explained

To test an object or piece of equipment, our calibration technicians load the object within the slot in the tensile unit. Tests can be set up based on a load, displacement, height or time limit. Breaks and ruptures can be detected and defined as a sharp break or percentage drop from the measurements taken. In other words, the machine works by using a ‘crushing’ or ‘pulling’ motion against the object to test its tension points and load limits.

Often described as ‘ultimate strength’ tests, tensile units measure the maximum stress by using grips on either side of an object, which can be applied to an object before it becomes stretched, pulled and ultimately broken.

Stress curves shown on a technician’s screen from the tensile unit shows how the material or object reacted to the test. The stress shown refers to the amount of force used per unit, while the strain shown is in reference to the ratio of change compared with the original measurement.

Watch Ametek's video to see the machines in action:

The tensile units we use are just a small part of CoMech’s armoury of specialist calibration equipment types we use within our specialist laboratories.

To find out more information about our tensile units and what they can do for you, get in touch with our team at sales@comech.co.uk or telephone 01332 867700.

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