What is mechanical testing?

Published - 22nd Aug 2017

In broad engineering terms, mechanical testing involves applying forces and pressure to a component or system and measuring its response. This is designed to check that the physical and mechanical properties meet the expected requirements and it performs as needed. This form of testing is used to measure properties such as tensile strength, hardness, impact resistance and elongation.

In this blog, we’ll be examining the process in more detail and finding out how it is used in our aluminium sand casting work.

Tested to the limits

Mechanical testing is an umbrella term that encompasses a whole range of activities. At Haworth Castings, the main technique used is tensile testing. This is a very popular test method in industry to characterise the properties of metals and alloys.

Tensile testing allows us to measure the ultimate tensile strength (UTS), maximum elongation of an aluminium sand casting and the proof stress – in other words the yield point at which it becomes permanently deformed.

The UTS is the maximum stress that the part can withstand while being stretched without fracturing. It is measured by recording the engineering stress versus strain. This is also known as Young’s modulus of elasticity.

How tensile testing works

Our tensile tests are carried out by a third-party supplier, Zurich Laboratories, to provide independent verification of the integrity of a workpiece. This is carried out on a test bar – a sample piece of metal taken from, or poured with, a batch of castings.

The test bar is placed in a test machine and locked into position between two cross-heads. It is then slowly extended and measurements taken until it breaks. These measurements are then used to obtain the stress-strain curve for the casting and the UTS – which is the highest point of the curve.

The performance of the aluminium sand casting can be influenced by a range of factors such as surface defects, the temperature of the test environment and preparation of the test bar.

At Haworth Castings, tensile testing is carried out specifically at a customer’s request for castings that are destined for use in high-stress environments.

Our highly skilled engineers offer a wealth of experience in aluminium sand casting. To find out more about our work, please call us today on +44 (0)1794 512685 or email us: sales@haworthcastings.co.uk