Angle too small
The neck of the ball seat that is easy to wear (the ball seat material is nickel-platinum copper or stainless steel, which is much easier to wear than the ball). If the object is written for a long time, even if the object is paper, the ball seat cannot withstand wear. This will cause the balls to fall off.
Right angle
When writing with a ballpoint pen, it is ideal to control the angle between 55° and 70°. At this time, only the ball is in contact with the paper (the ball is hard, tungsten carbide or ceramic, which is not easy to wear), and the closing part does not touch the writing. So as to ensure that the ballpoint pen prolongs its service life under good writing conditions.
