In order to be able to define the usability of a screw drive, the p * v value (pv value) is 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 applicability 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 pv value.
In addition to the frictional heat that can be derived from the application, many other factors are relevant for the maximum permissible pv value, for example the duty cycle, the ambient temperature, the stroke length and the heat dissipation values of the materials used.
These many factors are evaluated in the calculation using correction factors so that, for example, with very short switch-on times, the pv value can be exceeded very significantly for a short time.
In the case of short switch-on times, the maximum permissible pv value can be provided with a correction factor.
For duty cycles of less than 10% and appropriate lubrication, we recommend not to exceed the pv value of 0.6.
However, it is imperative to note:
In addition to the maximum permissible pv value, 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 provide the max. Calculate the permissible PV value 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.