Two physical properties that have a major influence on the cracking of workpieces, tools, or dies during thermal cycling are thermal conductivity and thermal expansion. Explain why.

Explanation:

It is generally known that the thermal stresses developed during thermal cycle results into cracking, and these thermal stresses are due to temperature gradients .

Stresses will be equivalently lower for a particular temperature gradient when the thermal expansion is low.

It also known that there will be a reduction in the temperature gradient if the thermal conductivity is high, as heat is dissipated faster and more equally and  with it, as well as  when deformation takes place due to thermal stresses, cracking occurs but if the ductility is high, more deformation will be allowed without cracking and thus reduces the tendency for cracking.

answer:

clock

explanation:

always running (on) sing each hour (chime) and the clock face (front)