The 15.01.606 key is a guiding and mechanical constraint component of the Gildemeister GM20 bar feeding system, mounted on sliding ring 1501604 by means of screws 1501611. Its function is to engage the longitudinal grooves of the system, allowing feed finger tube 1501602 to perform the axial translation required for bar feeding without losing orientation and without generating unwanted rotation in the guiding areas. Inside the kinematic chain the key works as a reference, reaction and guiding element: it keeps the ring correctly positioned in relation to the grooves, stabilizes feed tube movement and allows more orderly and repeatable motion transmission during the cam driven cycle. In the system for bars up to 25 mm, recommended for lighter work in the 20 to 25 mm range, the key is especially important because it must ensure smooth sliding and accurate guidance while operating in an assembly with slimmer components than solutions intended for heavier loads. A correctly mounted and clamped key reduces backlash, vibration, runout and small lateral displacement, contributing to stable bar feed and accurate positioning of the material against the bar stop. The quality of the coupling between key, ring seat and longitudinal groove directly affects cycle repeatability, dimensional consistency, reduction of geometric errors and the service life of the other components in the group. During maintenance it is important to check flank wear, deformation, drag marks, correct seating, absence of burrs and proper tightening of screws 1501611. If the key has excessive play or wear, the feed tube can lose linear sliding, generate vibration, produce uneven feeding and compromise functional synchronization with the rotation of the main spindles mounted inside the spindle drum. This spare part is intended for maintenance technicians and multi spindle lathe operators who need to restore precision, stability and reliability of the bar feeding system.