With the material fineness requirements are higher and higher, the use of sanding machine is more and more common, and the market grinding media is more, how to choose a more suitable for their own production process and conditions of grinding media, is a more critical and troublesome matter.The following aspects to make a simple analysis.
I. Chemical composition
The grinding medium can be divided into glass beads, ceramic beads (including zirconium silicate beads, composite zirconium beads, alumina beads, rare earth metal stabilized zirconia beads, etc.), steel beads, etc.Due to the difference of chemical composition and manufacturing process determines the crystal structure of the grinding bead, the compact crystal structure ensures the high strength of the bead, high wear resistance and low ink absorption rate.The percentage content of various components determines the specific gravity of the grinding bead, and the high specific gravity provides a guarantee for the high grinding efficiency.The chemical composition of the grinding beads in the grinding process of natural wear will have a certain impact on the properties of the slurry, so in addition to considering the low wear rate, the chemical elements should also be considered.Such as grinding tape powder or other electronic components paste, metal Fe, Cu and other elements should be avoided, containing Fe2O3 or CuSO4 and other components of the grinding beads are not among the choices, so the choice of zirconium beads is often the general choice of this industry;For example, in the fields of grinding pesticides, medicine and biochemistry, heavy metals are the key elements, and PBO is the most common component.
In short, some physical properties (hardness, density, wear resistance) determined by the chemical composition of the beads and the pollution of the paste by its own wear are factors to be considered in the selection of grinding media.
II. Physical properties:
1. Density of grinding medium
Density is expressed in terms of specific gravity (true specific gravity) and bulk weight (false specific gravity) in common documents. The molecular weight and percentage composition of various oxides determine the grinding density.
Under normal circumstances, the larger the specific gravity of the grinding beads, the greater the impulse, the higher the grinding efficiency, and the contact parts of the sand mill (cylinder, dispersing plate, etc.) wear is relatively large, so the paste viscosity and flow with become the key.Low density grinding beads for low viscosity paste, high density grinding beads for high viscosity paste.
2. Hardness of grinding medium
Mohs hardness and Vickers hardness are commonly used indicators. The higher the hardness of the grinding beads, the lower the abrasion rate of the beads does not mean.
For example, from the grinding beads on the contact parts of the sand mill (dispersion plate, rod pin and cylinder, etc.) wear situation, the grinding beads with high hardness on the contact parts wear more, but can be adjusted by the filling amount of the beads, slurry viscosity, flow and other parameters to reach the optimal point.
3. Particle size of grinding medium
The size of the grinding bead determines the number of contact points between the grinding bead and the material. The more contact points the small particle size beads have in the same volume, the higher the grinding efficiency will theoretically be.On the other hand, when grinding materials with large particles in the initial test, such as 100 micron slurry, D=1mm beads may not be successful, the reason is that the impulse of small beads can not reach the full energy of grinding dispersion, at this time should use larger particle size beads.
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Post time: Mar-01-2021