To simulation the friction between two tools friction model Coulomb is used, shear stresses on the contact surface depend on the normal contact pressure (σn) and friction coefficient (μ):

Heat transfer coefficient - is used for simulation the surface heat rate density during heat exchange between two contacting tools:

Here h - heat transfer coefficient, T1 and T2 - temperature of the tools in contact.

If the feature is enabled Non-separable, then the contact surfaces of the tools can slide relative to each other, but cannot come off from each other. The picture shows the permitted and prohibited movement direction of the contact nodes.

This feature is relevant for deformable tools.