Why do cat poop/clumps fall to the edge of the machine?

Step 1: Please check whether the cat litter is at the range of 60%-90% of the scale, if the amount of cat litter is insufficient, please add cat litter in time;
Step 2: It is recommended that the cleaning time be set to more than 5 minutes after the cat leaves, so that the poop can form a better clump and be easier to clean;