It dose depend on the design of the robot. Mega Mouse uses Aluminium armour very well, with a Hardox or similar blade on the front.
Cherub is made of steel armour not Hardox between 10 -5mm thick, and is so far impenetrable.
Saint is rubber conveyor and 3mm arm400 Steel, wheels 12mm UHMWPE,
Gabriel is 6.2mm armour steel at the front, and 20mm HDPE top and bottom wheels the same!
none are weak as far as armour is concerned, also Beast has no armour to speak off and survives very well.
do you have a picture of your design?