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Spring maker sees ‘added-value’ as the way forward

28 November 2011

William Hughes has been making springs for more than 200 years and has been at the forefront of the UK wire industry for a good part of that period. Now, this leading manufacturer of springs, bent wire-forms and assemblies is beefing up its specialist services to meet customer demand

There is a growing demand for single source supply among industrial purchasing managers; it’s a lot easier when you have just one point of contact to deal with when specifying a component and the way that it is finished and tested. The long established Dorset based spring maker, William Hughes is no stranger customer support strategies of this kind, but growing customer demand has prompted the company to introduce a number of new ‘added-value’ services. Among these new controlled processes are steel and glass shot peening, ultrasonic cleaning and tensile testing. Tensile testing is carried out either to very high national standards, such as Aerospace Material Specifications, or against parameters specified by individual customers.

Steel shot peening involves firing or blasting a known size of cut wire shot at a component such as a spring to create compressive residual stress layers that modify its mechanical properties. For many engineering applications, the desired outcome is increased spring longevity. The quality, size and intensity of the shot will define the shot peening process, with proven and established measurement techniques deployed to calculate the amount of stress delivered.

A number of tests are performed, all of which give customers total confidence in the shot peening process. For instance, after every eight machine working hours, the size of the shot is checked using a sieve shaker with different mesh sizes to ensure that it is correct. Additionally, visual screening under magnification is performed to check shot quality, confirming it to be round and without sharp edges.

Other shot peening tests include arc rise tests using an Almen strip designed to measure shot intensity against time. Here, a thin strip of steel (of which the size, thickness and flatness are known) is subjected to peening tests, initially to set the process, then regularly to control the process. William Hughes also undertakes coverage testing whereby paint or a luminous substance is applied to parts, peened and then viewed to determine how long the process must continue to achieve full coverage; this optimises the process and avoids over-peening.

The company can also offer shot peening using glass, a finer and smaller media preferred for smaller diameter wires and stainless steels. The use of glass media allows shot peening to be performed without contaminating component surfaces.

Today, the cleaning of components is an essential element of supplying manufactured parts, particularly for sectors such as aerospace. Because many of the aeronautical parts produced by William Hughes require heat treatment, pre-treatment ultrasonic cleaning ensures greater component quality. This is often the case with stainless steel components, where ferrous contaminants can be drawn in by heat treatment. High specification ultrasonic cleaning will remove any ferrous particles and avoid this unwanted effect. As a point of note for aerospace customers, the company is currently being assessed for NADCAP accreditation for heat treatment and tensile testing, with approval expected before the end of the year.

Tensile testing is now also offered following new investment in special equipment, and involves mounting both ends of a test piece (or wire) and pulling it until it breaks, measuring not just the tensile strength but the elasticity of the material, be it metal or plastic.
While the introduction of these new processes will benefit existing customers, William Hughes stresses that these services are also available on a subcontract basis for all customers, both existing and new.


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