The Challenge
To design and manufacture 4 compression springs which were needed to operate essentially non-axially, guided over a circular bar. To the best of our knowledge this had never been attempted before (see Figure 1)

The information provided by the customer was:

• The radius of the axis
• The required torque and angular rotations for each spring
• The environmental conditions
• A Stress Reserve Factor

The Approach
Firstly we had to evaluate the feasibility of the design. To do this we ignored the axis and converted the torque’s and rotations into simple compression and deflection figures.

3 designs were then produced to evaluate the differences in the pitch of each spring at the inside radius, the mean radius, and the outside radius. These designs were then checked for stress, relaxation and estimated cycle life.

A drawing was produced and the final design was then approved for manufacture by the customer.

The Solution
Initial attempts at manufacturing the springs to the required radius were unsuccessful. Each time the springs were compressed they constantly relaxed. Our calculations told us that this was not a design flaw more the result of the new manufacturing process. We then tried heat setting the springs into the desired radius but this bought about a different set of problems.
Finally the manufacturing process was fine tuned and the springs were supplied in to the customer.

The Benefits
The customer had created the concept, we provided the technical know how and dedication to help to realise the vision.
The cost to the customer was dramatically reduced because of our ‘buy in’ to the whole project.
The lead time of the prototype unit was also reduced, because the goals were clearly understood.

‘Together we CAN make a difference’