Contact between pin and hole

[mankas]

I am trying to model a thermal analysis in a piston, including the gungeon pin using different materials for each one. I have some questions about modelling the contact between them.

Does the pin's diammeter have to be smaller or equal to the hole's one?

The contact wizzard asks me to define a material and an element type. Does this element type have to be a contact element type or not? If it has to be a contact one, which is sutable for thermal analysis? What material properties I have to define for this type of element?

If you know a link for a similar tutorial, it would be helpfull.

Thanks