People often have questions about the play in sliding thread nuts made of plastic. This describes the lost movement, i.e. the "backlash" on the spindle. It is the gap between the thread flanks of the threaded spindle and the threaded nut. The term "game" is often used generally, but in this context, the correct technical term is "axial play." It describes the movement of the threaded nut in the axial direction without moving the spindle.
Sliding screw drives require a minimum of play in order to maintain their function. If the axial play is too small, the torque required to move the threaded nut also increases.
I Have to Pay Attention to That
In addition to the axial play caused by the manufacturing tolerances, the application-specific influences must also be taken into account. In addition to thermal and hygroscopic environmental influences, the minimum clearance to be taken into account in the application must also include the frictional heat generated during the application. This plays a decisive role in connection with the expansion behavior of the plastic material used. This means that the axial play present in the system can change with temperature fluctuations.
How Can I Reduce Axial Play?
In addition to the correct choice of material, a pretensioning mechanism has proven to be an effective measure to reduce the undesired play. There are three versions with preload for our dryspin® high helix threads and trapezoidal threads: Zero-Backlash, Low-Clearance and AB lead screw nut.
A standard lead screw nut should always be used for applications with high loads, high temperatures or in heavily polluted environments. The reason for this is that all three principles are negated in their effect by excessive loads. For this reason, the maximum static axial loads are specified separately for each threaded nut variant.