Custom Spring for Medical Application

Medical Device Industry – Custom Spring for Fetal Monitor

The Challenge:
The current process for manufacturing this barb-tipped spring required the customer to employ a secondary grinding operation to accurately produce a sharp angled tip at the end of the conical spring. Individual springs were procured – less the barb tipped end. Springs were then handled one at time and staged in holes in a circular cutting fixture. This was time-consuming, costly and a production constraint. Could Springfield Spring & Stamping fully automate the manufacturing process for these springs, reduce cost, improve daily manufacturing output and replicate the part’s form, fit and function?

Springfield Spring’s expertise was enlisted with the medical design team at the formative stage of development to confirm essential characteristics and critical features to consider and ensure cost-effective product realization.

The Solution:
Springfield Spring & Stamping had prior experience with manufacturing rectangular shaped surgical staple prototypes. These prototypes required us to put a sharp angle cut at both ends of round titanium wire as an integral manufacturing process. A specially engineered cut off tool was developed by our CNC wire forming engineering teams to accomplish this. When we were presented with the challenge of putting a sharp angled cut at the tip of the conical spring for the fetal monitor application, we were able to easily leverage our prior tooling and manufacturing process for this new application. A new tool was developed, and samples were provided to the customer. Under high magnification it was determined that the angle cut was very sharp but still required a minor deburr. Not a problem. Our teams introduced a high-speed dermal-type deburring operation as an integral part of the manufacturing process after the angle cut at the end of the spring. The parts were re-summited for testing and easily passed acceptance. Challenge solved!

Project Specifications
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Product Description
Conical compression spring with a sharp skin piercing angle cut at the tip of the spring.

Primary Development
Leveraged existing process to accomplish new objective

Production Tightest Tolerance Material Used
Parts produced on state-of-the-art CNC wire forming machine Spring free length +/-.005
Angle cut +/- 2 -degree
.026 – Type 316 LVM medical grade spring tempered stainless steel wire

In Process Testing/Inspection Performed
In Process SPC
Keyence Vision System

Benefits
Increase daily production output
Reduce component cost
Improved angle cut quality