Lubrication grooves fulfill an important task in metallic bushes. Through them, the lubricant gets directly into the bearing point between the buchse and the shaft. The lubricant thus protects the shaft and bushing from dirt and moisture and ensures low coefficients of friction.
The disadvantages: On the one hand, a buchse with a lubrication groove is quite complex to produce, since the groove represents an additional machining step and the inner diameter, depending on the dimensions of the buchse, is difficult to achieve with cutting tools. On the other hand, the permanent supply of lubricants can only be guaranteed through seamless maintenance.
Either the lubricant has to be replenished by hand using a grease gun or something similar, or it has to be automatically replenished using an expensive central lubrication unit. Last but not least, the lubricants end up in the environment. The lubrication grooves guide the lubricant through the bearing point to the outside. An aspect that has become increasingly important in recent years. It has long since ceased to matter where the lubricants end up.
So it makes sense to look for alternatives. What could you do without oil grooves? And maybe design the lubrication differently?