First, identify the appearance of the "broken" beads. If the particles are relatively smooth and not sharp-edged like broken glass, it is actually natural wear of the beads. These beads may be worn into various shapes such as disc-shaped, elliptical, or smaller spherical shapes. This condition is called abrasion, which only varies in the degree of wear.
From a force perspective, when the dispersing disc transfers energy to the beads, if the liquid viscosity is low, such as when cleaning the grinding machine with solvents or water, the thrust of the material may not be sufficient, and the beads may come into contact with the dispersing disc and break. This is why we recommend minimizing the cleaning time. If low-viscosity liquids are used to clean the machine, the beads may also wear out other beads or components of the grinding machine. To ensure the longest service life of the grinding beads and the grinding machine, it is best to use resins for cleaning and maintain sufficient material viscosity during production.
Many people encounter broken beads when they empty old beads and load new ones for testing. Let's analyze this issue and discuss possible solutions.
1. Incorrect installation of internal contact parts in the grinding machine: loose dispersing disc or sharp edges on the disc's edge, foreign objects inside the grinding machine, loose valves, etc. These situations may cause the grinding beads to break.
2. Wear or improper installation of contact parts in the grinding machine: the dynamic separator or screen mesh may be worn out, the screen mesh may have broken or been installed incorrectly. If the grinding media pass through the separator and enter the feeding pump, the pump may crush the beads before it gets clogged or shuts down.
3. Back pressure: When the feeding pump is turned off, the residual pressure inside the grinding machine can push the beads into the pump. So when the pump starts again, it can crush these beads. One-way valves are not always reliable and sometimes allow beads to pass before closing.
4. Accumulation of grinding beads: If the grinding beads accumulate at the bottom of the grinding machine or the working pump's high speed causes the beads to concentrate at the exit of the horizontal grinding machine, this situation may occur. The solution is to start the grinding machine with a jogging mode of "on-off-on-off" to loosen the accumulated grinding beads.
5. Wear of the dispersing disc: This situation may be more difficult to determine. The worn edge of the dispersing disc becomes uneven, and the edge of the dispersing disc is where the linear speed is the highest and strong vortices may form. In addition, for vertical grinding machines, the grinding beads tend to concentrate near the lower part of the dispersing disc due to their own weight. These factors combined can cause the grinding beads to break. Excessive wear of the dispersing disc is often caused by slow pump speed and high density of grinding beads. This problem can be solved by replacing severely worn components and reloading the same batch of grinding beads.
6. Mixing grinding beads from different manufacturers. Products from different manufacturers may have different densities. Doing so will intensify the mutual wear between the beads. The solution is to never mix grinding beads from different manufacturers. If you suspect that mixing has already occurred, you must dispose of all of them.
7. Accidentally adding used old beads to the grinding machine.
8. Garbage or small worn-out beads: Often, garbage or small worn-out beads are attached to the screen mesh, shaft, support, or other corners inside the machine. When adding new grinding beads, these small particles may loosen and mix with the new beads. This may create an illusion of immediate breakage of the new beads, but what you see is actually some naturally worn beads.