Page 32 - Industrial Technology February 2020

DESIGN ENGINEERING

ALLOY CHOICES

SPRINGS AND DAMPERS

WHEN CHOOSING A SPRING FOR YOUR INDUSTRIAL APPLICATION, ONE OF THE MAJOR
CONSIDERATIONS IS THE MATERIAL, AS THIS WILL DETERMINE THE SPRING’S SUITABILITY
FOR THE ENVIRONMENT IT IS WORKING IN. CHOOSE THE WRONG ONE AND YOU COULD
BE FACING A COSTLY REDESIGN OR REPAIR JOB DOWN THE LINE. JUSTIN LAWRENCE,
APPLICATIONS ENGINEER AT LEADING FASTENING AND FIXING SUPPLIER TFC, EXPLAINS
THE SUITABILITY OF DIFFERENT ALLOYS FOR SPECIFIC ENVIRONMENTS

hen choosing a spring, the choice of As a result, corrosion is a much more relevant threat
materials range from standard carbon to carbon steel, which is vulnerable to atmospheric CONSIDERATION THROUGHOUT
spring steel, through a variety of stainless damage when not properly sealed. For improved THE DESIGN PROCESS IS CRITICAL
Wsteels and all the way to more exotic nickel- performance 17-7 stainless steel has a similar corrosion
TO ENSURE THE SPRINGS WILL
chromium alloys. To make an informed decision regarding resistance up to 302 stainless, whilst offering excellent
what material is best for your application a good spring properties. 316 stainless offers higher corrosion FUNCTION CORRECTLY
understanding of the properties of each alloy with respect resistance due to its molybdenum content and is widely
to temperature and corrosion resistance is essential. used in chemical or sea water applications.
Highly corrosive environments can often require more SMALLEY WAVE SPRINGS
Temperature resistance than the protection offered by stainless steel. High-
The first environmental factor that can influence the performance alloys such as Inconel and Elgiloy are TFC is the leading European supplier of Smalley Springs
material choice is temperature. When springs are used in specifically designed to survive harsh environments. and Retaining Rings. The Smalley range of standard
environments close to or outside their recommended products consists of some 10,000 parts stocked in carbon
operating temperatures, it can lead to permanent Cost effectiveness and stainless steel.
deformation, or in the case of extreme cold, to a brittle By consulting with a fastenings and fixings company with
fracture. a wealth of experience in springs, designers can learn If you can’t find a part to suit your needs then Smalley’s
For applications operating at ambient temperatures, about what options are available to them and which are No-Tooling-Cost manufacturing process allows for fast
SAE 1070-1090 carbon tempered steel’s maximum most appropriate and cost effective for their application. prototyping and production. TFC’s team of engineers are
recommended temperature of 121°C will probably serve They can then benefit from the experience of a specialist available for design consultations, providing a range of
you well. This standard material is widely used in many spring designer, who can develop bespoke springs to meet resources to ensure the application contains the most
industrial applications. Tensile and yield strength are the required load characteristics and to operate in the effective solution.
maximised as a result of the oil tempered martensitic harshest environments.
structure.
For applications involving elevated temperatures,
17-7 Ph/C stainless steel offers up to 343°C as a
maximum recommended temperature. Spring properties
are achieved by precipitation hardening condition C to
condition CH900.
A286 stainless steel, or maybe Inconel 718 are the
pinnacle of heat resistant alloys, boasting maximum
recommended temperatures of over 500°C. However,
these materials come with a much lower tensile strength,
meaning careful consideration throughout the design
process is critical to ensure the springs will function
correctly.
For extreme low temperatures, such as those in
cryogenic systems, choice of material is equally
important. In these applications 300 series stainless
steels or Nickel alloys are normally preferred.

Corrosion resistance
Alongside thermal damage, corrosion can also cause
springs to fail. Corrosion occurs when metals react with
their surroundings, this can lead to microscopic cracks
that will eventually fail.

MORE INFORMATION: www.tfc.eu.com • sales@tfc.eu.com • Tel: 01435 860349

INDUSTRIAL TECHNOLOGY • February 2020
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