What is Special Shaped Wire?

Springs Magazine 2012Originally Published – Fall 2012 – Springs – By Scott Kirkpatrick

By now most readers will have seen the reprint of the premiere issue of Springs from May 1962. Radcliff Wire, Inc. is proud to be acknowledged as one of the six loyal advertisers that spans the 50 years of the magazine’s history.

In the spring of 2009 Radcliff Wire celebrated its own 50 year milestone. Our company started in Don Radcliff’s small garage and has grown to two facilities across the road from the headquarters of ESPN.  We have come a long way from producing basic square and flat wire to the development of more sophisticated shapes in many various alloys.

When the layman off the street asks, “What is special shaped wire?” Most of us take it for granted that everyone knows the answer. Our answer begins with the questions and observations from everyday life:

  • How do you think those eye glasses with the brass frames were made?
  • How about the nice stainless steel band from your wrist watch?
  • The guitar you play has frets made from specially designed half round wire.
  • Remember the Slinky you played with when you were a kid?

shapesWhat is special shaped wire and how does it benefit the spring industry? It is a customer specific shape that includes dimensions, tolerances, edge requirements, temper, etc. It is specific to alloy, to packaging, and to surface condition. Flat and square wire designs utilize more material density than traditional round wire springs. Trapezoidal shapes allow springmakers to coil wire evenly by compensating for distortion. This basically stretches the outer or thicker area of the trapezoidal wire to equal the dimension of the inner portion on the spring while coiling. Working with shaped wire allows springmakers many different possibilities when designing a spring.

Spring manufacturers have their own answers about shaped wire for the layman: As you turn the knob on your home front door it springs back. Your automobile has over 900 springs and wire forms; many are made from flat or square wire that controls locks, seats, engine components, and audio devices. Radios, CD players, televisions and phones all react at the turn of a knob or click of a button.

It is known that shaped wire is used in the most obscure yet important products:

  • Every rivet used to attach the skin of an aircraft to its frame includes a locking tab made from  a very uniquely designed shaped wire.
  • That powerful engine may need a diamond shaped wire spring, used as a threaded insert to secure a bolt or a spark plug.
  • Many medical instruments require very close tolerance shaped wire to control a surgical device.
  • Most computer laptops have a flat wire spring-clutch to hold the screen open.

The manufacturing of close tolerance, high-quality shaped wire requires a comprehensive formula that begins with a basic round wire. This process may call for “extensive drawing” of this basic wire, using many drawing dies to achieve a starting wire size that can now be rolled. With a mathematical protocol that includes “furnace annealing” and “cold work rolling,” sometimes many cycles of each, this process will end up delivering the desired custom shaped wire.

October 2012 AdThe basic method of producing most shaped wire has not changed over the last five decades. Adding modern electronics and slight technical modifications, many of our older rolling mills and turks-heads are still in use today, continuing to produce good quality shaped wire for many spring applications.

As history demands, there have been many developments in the science of producing wire shapes, as their prerequisites have become more demanding. Wire manufacturers are forced to design and build their own production equipment, as well as the unique tooling necessary for special shapes. As simple as the concept sounds, it should be noted that it takes a great deal of experience to develop the process of shaping precision wire. Designing a spring, utilizing shaped wire, can be very cost effective. It can be a much stronger spring, and it can help by reducing space requirements.

We challenge our spring manufacturers to review the prospects of using more shaped wire designs, for this method appears to be the future and could be an aggressive way to build one’s business.