Details of Millling technology

The operation of reducing the size of a solid = increasing its specific surface area is called milling. The specific surface area is the surface area per unit mass and is very important for physical and chemical reactions. A wide variety of materials are milled for various purposes. The following effects can be expected from milling raw materials.

1. Coarse or Medium milling (about 100 to several hundred microns)
Improvement of handling, flowabilty, dispersibility, separation of components (processing of recyclables), improvement of efficiency in fine and ultrafine grinding processes, dispersion of agglomerates, etc.

2. Fine milling (about several tens of microns) and ultrafine milling
Increase in specific surface area, shape control, surface modification, solubility improvement, color adjustment, sintering improvement, magnetic and electrical property improvement, tactile improvement, etc.

For more information about milling itself, please see the "What is milling?" page.

Mill performance

There are many different types of crushers, which apply compressive force (crushing of solids), shear force (cutting of solids with cutters or knives), impact force (force exerted on solids by the impact of a hammer rotating at high speed) and friction force (crushing of solids). It is important to understand the purpose of the milling and the properties of the material to be milled in order to select the right machine for the purpose.

(1) Particle size and particle size distribution of milled products

The most important aspect of any milling operation is that the particle size or size distribution of the milled product meets the requirements. Whether the requirement is to limit the maximum particle size of the milled product, to limit the maximum and average particle size, or to limit the size distribution of the product, the milling machine is selected to meet these requirements. In some cases, the requirements cannot be met by the mill alone, but can be met by the use of a classifier.

(2) Raw material characteristics

When selecting a milling machine, it is important to fully understand the characteristics of the raw material. If the characteristics of the raw material are not taken into account, problems such as "the desired particle size cannot be achieved but continuous operation is not possible" or "running costs are too high due to wear" can occur. The characteristics of raw materials include moisture content, hardness, abrasiveness, toughness, permissible temperature, melting point, hygroscopicity, adherence, ignition, toxicity and corrosiveness. For example, for highly abrasive materials, or for materials where contamination from the mill due to abrasion is to be avoided as much as possible, we recommend the use of abrasion-resistant models or models with a powder contact area made of ceramics. For explosive or hygroscopic materials we recommend a nitrogen system, and for materials with low melting points or low heat we recommend the use of a cold air generator or a freezing system with liquid nitrogen.