Page 32 - Industrial Technology magazine February 2021 issue

DESIGN ENGINEERING

WAVE OR COILED?

SPRINGS AND DAMPERS

SIMON WARD OF TFC, EUROPEAN PARTNER OF SMALLEY, COMPARES
CREST-TO-CREST WAVE SPRINGS AND ROUND WIRE COIL SPRINGS

rest-to-Crest wave springs can offer similar loads applications, such as handheld instruments like dental
and deflection to traditional coil springs, but at tools and insulin pens, which must be lightweight and
around half the height. They can reduce axial compact. A wave spring, true to its name, utilises a
Cspace by up to 50 per cent, leading to an overall sinusoidal waveform to generate the required axial force.
decrease in assembly size, weight and cost. For design A Crest-to-Crest wave spring has multiple turns to build up
engineers looking to utilise these benefits and discover if a the free height of the spring to achieve the required
Crest-to-Crest wave spring can replace a coil spring in deflection characteristics.
their application, let’s try to answer some common Another difference is the way that wave and coil
questions about wave springs. springs store and release energy. A coil spring has a pitch
What are the key differences? Wave springs angle and is torsional so it can twist as it compresses,
and coil springs are both types of compression meaning not all force is necessarily aligned with the axis.
spring, primarily used to provide an axial force in On the other hand, wave springs rely on bending – as load
either a static or dynamic application. However, is applied, the waves begin to flatten, providing an upward
there are differences. Coil springs are typically force, allowing for complete axial load transmission.
made of round wire, whereas wave springs are How do I swap from using a coil spring to a Crest-to-
made from flat wire. This provides an opportunity Crest spring? For design engineers currently using coil
to significantly reduce working heights within any springs, switching to a Crest-to-Crest wave spring needs
assembly. Space-saving is key in medical careful consideration. There is an extensive range of
standard sizes that may suit but in 70-80 per cent of
cases we will develop a bespoke design to maximise the
benefits.
Before designing any wave spring, it helps for TFC to
understand the space constraints and the spring
performance characteristics. The final design is then
achieved by modifying the number of waves and turns,
adjusting material cross section and wave heights. Choice
of material also affects the design and will normally be
dictated by the operating temperature and environment
where the spring must function.
If a Crest-to-Crest spring does not suit the application,
then there are several other options including single turn
and nested springs.To identify the correct wave spring for
your application, the best thing to do is work with a
specialist. An experienced TFC engineer can help you find
the ideal wave spring, to help you achieve design
breakthroughs.
MORE INFORMATION: www.tfc.eu.com

Springing into action saves the day for automotive tier one

illiam Hughes has come to the aid of a prototype parts in just four weeks.” explains George Cairns
leading automotive seat manufacturer. The at William Hughes, “the customer hit a scheduling snag,
order, which was for seat frames and trim which ended up with us having a very short time period in
Wwires, comprised a number of different which to produce the first thousand pieces.”
complex parts, all of which would see use in five different Very few companies possess the capabilities, skillset
vehicles types, including SUVs and saloons. and knowledge that would enable such a complex and
In addition to bending and forming, several of the large design, test, manufacturing and delivery campaign to
frames also required welding. The accuracy demands be achieved in such a short time. “Our customer is de-
were such that engineers used 3D scanners and Vernier lighted,” says Cairns. “We were able to deliver 80% of the
calipers to ensure the parts precisely matched the order a week ahead of schedule, which gave it enough
customer specifications. “Although we had won the order capacity to meet the OEM’s delivery timescales.”
a few months previously, and had turned round the MORE INFORMATION: www.wmhughes.co.uk

32 INDUSTRIAL TECHNOLOGY • January/February 2021