Fasteners are everywhere and our modern world depends on them. Nuts, bolts, screws and rivets are used to join components, metal sheets and sections, which must not separate under load. In this article we take a quick look at this important industry sector and how Sercal can help your quest for quality.
It is said that there are only a few basic ways fasteners can fail, but failure can be caused by many different things. Testing is the key to understanding the correct application of fasteners to give a long and reliable service life. For example understanding the elastic tensile modulus and the limits of elastic loading of a screw will determine the recommended torque settings, precise testing of a rivet under load will allow the calculation of the recommended clearance hole sizing and settings for pneumatic hammers and squeezers.
During the design, manufacture and testing, many types of tests will be performed including :-
- Tensile tests, where the fastener is 'stretched' to determine the elastic tensile modulus and the limits of elastic loading of the part.
- Shear testing, where the fastener is subjected to axial loading ('slicing') in a custom rig which may test just the fastener or a jointed specimen.
- Fatigue testing, where, in addition to static loads, fasteners are subjected to frequent cyclic loading, including vibrations. Fatigue tests on screws and bolts are most quickly and efficiently performed in a Vibrophore, which can apply cyclic loads with a maximum force of up to 1000 kN in a frequency range up to 300Hz. Any changes can be measured with an extensometer to produce detailed reports on how the item reacted under load.
Sercal can work with you to develop a specification for the correct gripping of the specimen or component and then produce the required arrangement. These test devices can be simple or very complex, but always do exactly what is required of them.
As with all testing equipment, it is important that regular maintenance and traceable calibration is undertaken as part of your quality regime. Sercal can provide these services and a wealth of experience to help you develop and maintain your lab and it's equipment.
Are you testing fasteners? Contact us now to discuss how we can be of service to you.