One of the most important steps in the quality control procedure of grinding balls is visual inspection. Having no access to any experimental laboratory equipment but eyes, the very first thing that draw customers’ attention when they are inspecting a batch of grinding balls is grinding balls surface and shape!
The primary thing that has to be checked in quality control procedure, is the characteristics related to ball’s appearance, meaning the things that can simply be seen with the plain eyes, and no tools like magnifier.
In grinding balls visual inspection, the most important defect to look for is surface cracks. Cracks can result in material decay and premature collapse. So, it is the first item on the list. Then you should see if you can spot any un-normal defects, cavities, burrs, extremely rough surface, inclusions of unwelcome materials or irregular macro-structures. The importance of surface defects like adhesive residues or micro defects on the ball depends to the customer’s sensitivity on grinding balls visual inspection when receiving loads.
The second grinding balls visual inspection step is to inspect the diameter of the grinding balls, in three perpendicular directions. The dimensions of three balls form each batch should be measured, by a caliper. If the measured amount, exceeds the original diameter of the ball, by a value more than 2mm, the ball fails to pass acceptable diameter tolerance.
On the third step, individual balls and the whole jumbo bag should be weighed. Considering the density and volume of the material (V=4/3πR^3, where V and R represent volume and ball radius respectively) you can calculate a predicted mass (m=ρ.V where ρ, m and V represent density, mass and volume respectively) which should match the measured value. Then if you multiply that amount to predicted number of the balls in the bag, it should match the weight of the whole batch.
If any of the mentioned defects are spotted in more than 10-15 items in a batch, the whole batch is rejected.
As you already noticed, even simple, grinding media visual inspection is an important part of the product inspection, where simply, by three steps, some of the most important specifications of the grinding balls can be checked!