The bar-guide spring  0818010 for Ø4–Ø7 mm bars is used to keep the bar stable inside the bar guide tube on Gildemeister multi-spindle automatic lathes AS16, AS20, GS20, GM20, GM20AC.

When the bar rotates at high speed, it does not always stay perfectly centered. This happens because rotation generates a force called centrifugal force, which pushes the bar outward. If the bar is long, slender, or not perfectly straight, it tends to oscillate (like “whipping” inside the tube). This oscillation creates vibration, noise, and instability, and it can reduce machining quality.

The spring is installed inside the bar guide tube and works like an elastic guide. Its coils (the turns of the spring) contact the bar and “support” it during rotation. Thanks to its elasticity, the spring does two key things: it keeps the bar more centered and it dampens vibrations, meaning it absorbs part of the shocks and oscillations that would otherwise turn into machine shaking.

The fact that the spring is specified for a range such as Ø4–Ø7 mm is not random. It means that within this range the bar is guided correctly. The minimum and maximum diameters that can pass depend on the maximum allowable bar oscillation and on the bar rotation speed. In practice, the faster the bar rotates and the more “sensitive” it is (thin/long), the more important it is to use the correct guide, because even small deviations can cause vibrations to increase.

If the wrong spring variant is used (not suitable for the bar diameter or operating conditions), several problems may occur. The bar can be marked or damaged because it is guided incorrectly or rubs abnormally, excessive vibrations can start because the bar is no longer properly contained, the bar feed can become irregular (the bar may not slide smoothly and can bind), and as a result accuracy during machining is reduced, with poorer tolerances and surface finish.

In short, this spring is a simple but critical component: it helps the bar rotate in a stable way, reduces vibrations, and supports both bar feeding and machining precision.