Product category:
Springs, dampers, latches, locks and small components
News Release from: TFC | Subject: Smalley crest-to-crest Spirawave springs
Edited by the Engineeringtalk Editorial
Team on 05 February 2003
Springs into action for electric motor
maker
Flat wire Spirawave springs from TFC have helped an electric motor manufacturer overcome a unique design problem.
Flat wire Spirawave springs from TFC have helped an electric motor manufacturer overcome a unique design problem The product being manufactured was a brushless electric motor used to supply the energy to the power steering in smaller horsepower vehicles
This article was originally published on Engineeringtalk on 29 Nov 2002 at 8.00am (UK)
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The motor, driving a hydraulic pump located directly on the steering rack, eradicates the traditional belt drive from the crankshaft, making it more reliable and efficient.
However, the conventional die-stamped wavy washer used to pre-load a standard 608 bearing on an 8mm shaft in the motor gave erratic results, leading to increased noise and excess wear.
It was established that these difficulties were caused by the limited working height available for the spring, which varied between 2.2mm and just 1.42mm when tolerance build up was taken into account.
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The die-stamped spring was unable to offer a controlled spring rate over these maximum and minimum conditions.
TFC was employed to find a spring that would satisfy these specific design requirements and provide enhanced performance.
The answer came in the form of a Smalley crest-to-crest Spirawave spring as it was capable of operating consistently over the working heights demanded.
Indeed, Spirawave springs are able to develop similar forces to conventional round wire or helical springs while occupying a third or less space.
TFC created a bespoke four-turn spring design from narrow section 17-7 precipitation hardened stainless steel flat wire to deliver the most effective spring rate within the space available.
Because Smalley's manufacturing process uses no bespoke tooling, this allowed TFC to reduce the lead-time and costs dramatically.
The final product resulted in uniform loading of the bearing over the operating range of the spring, eliminating the problems previously encountered.
"With such a specific design brief, we needed to deliver a specific solution", said Brian Goode, Technical Director at TFC.
"Smalley crest-to-crest Spirawave springs were clearly the answer since they supply equal deflection forces to conventional round wire springs but occupy up to a third or less of the space".
"Another important factor was that because the Spirawave springs are drawn from a continuous coil of single filament pretempered wire, there were no associated tooling costs.
We could, therefore, deliver a unique solution to meet the electric motor manufacturer's needs both quickly and economically". Request a free brochure from TFC ...
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