This largely depends on the hardness of the wood you're chipping. The harder the wood, the quicker the blades will need to be replaced.
However, the chipper is equipped with twin reversible blades. The reversible blades mean that you can simply switch the blades around when the first set start to dull, so you get a much longer life span on the blades.
We also stock spare blades on our website, should you need to have them replaced.
You can also sharpen your blades using an oil stone. Simply sharpen the edges of the blade, do not worry about taking out any dents or marks.