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Custom Fabricated Extension Spring for Lawn Equipment Manufacturer


Industrial Spring Corporation, a high-quality extension spring design and manufacturing company, was assigned a custom music wire extension spring design and fabrication project by a client in the power lawn equipment industry. The main objective was to prevent the extension spring from breaking, an issue the client faced with their current spring. To accomplish this goal, we proposed and implemented four design changes to the current spring including changing the raw material to direct draw music wire, the finish to Magni 565, reducing the end coil & hook diameter, and adding shot peening to produce a compressive residual stress layer. These alterations were successful in improving spring performance and reducing warranty claims.

The direct drawn (.207” diameter) music wire was manufactured into a 24-coil extension spring, free length of 7.000”, O.D. of 1.750”, with tolerances of ±.013”.

It was manufactured using our state-of-the-art equipment, such as our AIM 3000 CNC spring coiler, Sleeper & Hartley looper, and Pangborn shot blasting machine. To ensure the spring met our breakage prevention objectives, we tested the part using spring rate and load testing.

Industrial Spring lived up to its reputation for rapid turnaround times and quality services by producing 7,500 extension springs in 25 days, including delivery to our client. To learn how our customer-oriented professionals can help you with your springs or formed metal projects, contact Industrial Spring.



Extension Spring Design and Manufacturing Services

Our client was having issues with extension springs breaking. Industrial spring proposed 4 design changes to prevent the spring from breaking.

Precision Metal Forming Capabilities Applied / Processes

Primary: Development

  • Proposed & Implemented 4 Design Changes to the Spring
    • Changed Raw Material
    • Reduced End Coil & Hook Diameter
    • Changed the Finish to Magni 565
    • Shot Peening to increase cycles in spring and hooks.
  • Changes Greatly Improved Performance & Reduced Warranty Claims
Coiling Looping
  • Form Ends
Secondary: Heat Treatment Shot Peening Coating Packaging

Equipment Used to Manufacture Part

AIM 3000 CNC Spring Coiler Sleeper & Hartley Looper Pangborn Shot Blasting Machine

Overall Part Dimensions

Wire Diameter: Ø.207” Free Length: 7.000” O.D.: Ø1.750” 24 Coils

Tightest Tolerances


Material Used

Direct Drawn Music Wire

Material Finish

Magni 565

  • 1,000 Hours of Salt Spray Testing Up from 96 On Previous Finish

In process testing / inspection performed

Dimensional layout - Spring Rate and Load Testing

Industry for Use

Power Lawn Equipment


65,000 Annually

Delivery / Turnaround Time

25 Working Days

Standards Met

Customer supplied print, 2D CAD Drawing

Product Name

Extension Spring