The small compression spring inside a click pen is easy to overlook, but it is the heart of the mechanism. A pen manufacturer approached us because the click on its premium range was not good enough. Customers reported an inconsistent clicking action, and the mechanism did not last as long as it should.
The Task
We were asked to design a custom small compression spring that gives a smooth, reliable click, lasts longer, and still fits the very limited space inside the pen.
Our Solution
Material
We chose AISI 304 stainless steel. It provides the strength and corrosion resistance the application needs and is well suited to springs of this small size.
Design
- Dimensions: with so little room inside a pen, the dimensions are critical. We selected a wire diameter of 0.5 mm and an outside diameter of 2.5 mm.
- Coils: a high coil count with a tight pitch gives a smooth, even compression rate, which is what makes each click feel the same.
- Tolerances: tight tolerances keep the performance consistent from one pen to the next.
Testing
The spring was tested for 100,000 compression cycles to simulate long use. It was also tested under different environmental conditions to confirm its durability.
Results
- Smoother operation: the click mechanism became noticeably smoother and more reliable.
- Longer life: the life of the click mechanism increased by 50% compared with the previous design.
- Easy integration: the new spring fits the existing pen structure, so assembly did not have to change.
What This Project Shows
With very small springs, tiny differences in wire or coil size change the feel of the product. Consistency in manufacturing matters as much as the design itself, because the customer judges the pen on every single click.
If you need small precision springs for pens or other compact mechanisms, contact us through the contact page, or read about our custom compression springs.
