Hi,
Even if you are only printing on Black, the printer needs to perform its oun maintenance on the ink system. Therefore you will eventually have to replace the color cartridges (after a long time).
If the printer does not perform this maintenance the printbar and the ink system will be damage and you will end up with a damage printer that will not allow you to print at all.
As Imagenet_Tech mention, you can set the software to print using black ink only, instead of the composite black (combination of color to produde black) to reduce the consumtion of color ink on your prints.
I hope this helps.
Best regards
Mike G