Sliding screw drives are generally not suitable for continuous operation. The heat generated by friction is the limiting factor for the duty cycle. This heat must be able to be dissipated from the system.
In order to be able to define the maximum permissible duty cycle of a screw drive, the p * v – value (pv value) decisive. Frictional heat arises mainly when high loads (p) are combined with high speed (v). If only one of the two values is very high, the duty cycle is less limited.
The use of a sliding pair with the lowest possible coefficient of friction naturally fundamentally reduces the pv value. Choosing the right one Lubricant significantly helps to minimize friction and increase the maximum permissible duty cycle.
In addition to the pv value, heat dissipation is also an issue. If the heat can be dissipated via the spindle or nut, longer duty cycles can be made possible. Plastic nuts are of course disadvantageous here, the use of an aluminum spindle would be advantageous.
The stroke length also has an influence. With very short strokes with a long duty cycle, more heat is generated than with a comparable application with a longer stroke, as the heat can get better out of the system via the spindle.
With regard to a high duty cycle, external cooling can also be an option. This can be done through the construction, for example through a cooling channel in the spindle or through the environment, for example through a fan.
In the case of short switch-on times, the maximum permissible pv value can be provided with a correction factor.
However, it is imperative to note:
In addition to the max. permissible duty cycle, the wear must be considered separately in each case.
junaspin is happy to support you in the selection and design of your screw drive. We are happy to increase the max. Calculate the permissible duty cycle of your screw drive for you, taking into account the service life. In addition to the calculation, we can also incorporate experience from “real applications” and tests.