How to select a good quality no crush wheel? Firstly, raw material is the most important. LLY PACK sun wheel is made from Polyurethane which is high elasticity, high wear resistance, high friction coefficient, no harm to paperboard. Besides, we should select the moderate hardness of crush free wheel. If the harness is too low, the wheel will deform. If the hardness is too high, the cardboard may be crushed. Our sun wheels hardness is 58HA that is good for cardboard quality. Tailor made specifications for all corrugator brand