Springs for Ballpoint Pens
Definition: Compression springs used to push a ballpoint pen out of its case and return back into the case. Used for click mechanisms.
The springs used in retractable ballpoint pens are compression springs. They are also known as coil springs or helical springs. Find stock compression springs for ballpoint pens using our free online Compression Spring Finder tool. Spring Finder will allow you to find a similar spring in stock according to your dimension tolerances. This tool allows you to enter your tolerances as ranges from minimum to maximum.
Springs for ballpoint pens must have enough elasticity to compress down to solid height because we tend to push it all the way in before letting the push-pin go. If the spring doesn't have the capacity to compress down to solid height, we will force the spring to take a permanent set, causing the spring to lose its free length, travel, and force. This means that the spring mustn't have a tight index and it must have enough coils in proportion to its free length and wire diameter. The more open your spring's diameter is and the more coils you have, the lighter your spring will be.
The measurements taken into consideration when designing compression springs for ball point pens are the following:
Outer Diameter -This dimension is important for your spring must be able to fit inside the pen's “barrel” or “tube”.
Inner Diameter -This dimension is crucial since the spring isn't only surrounded by tubing but it is also placed over a shaft. The spring mustn't be either too tight or too loose around this shaft.
Wire Diameter -This dimension defines the inner diameter from the outer diameter and vice versa. Changing the wire diameter will affect either one of these dimensions.
Free Length -The free length determines how long your spring will be when unloaded. This measurement allows you to calculate the distance traveled down to the solid/loaded height thus allowing you to calculate working loads as well.
Active Coils -Active coils are those coils which are open (have pitch in between them) and eject the force/energy. If your spring has closed ends, these will not count as active coils.
After the physical dimensions, you must focus on the working loads. Working loads can be calculated by diving multiplying the spring rate by the distance traveled.