1 Periodically shut down the VSI Crusher (sand making machine) and open observation door to check the how worn the liner is. Check the conical cap of the central input pipe, the top side and down side liner plate of impeller, crushing chamber liner, and cast hammer head. If any is badly worn, change them. And when hammer head need to be changed, please make sure to change them together to keep balance. Please attention that without the permission from our techniques, other impeller is absolutely prohibited to be use in sand making machine. Do not open the observation door when VSI Crusher (sand making machine) is working otherwise that’s not our responsibility. 2 During running, as the VSI Crusher (sand making machine) is fast rotating, please be careful your safety, workers should be far from the sand making machine. If check is need, shut down it fist, then do next.