We often hear about 1250 mesh, 800 mesh, and 400 mesh talc powder in the powder industry. So, what is the unit of measurement for this' mesh '? Is it appropriate to use it to describe the fineness of the powder? This article will trace back to this concept and its corresponding models.

1. The concept of "mesh": If you search online, most people think of the number of mesh holes on a 1-square inch sieve, while others think it is the number of mesh holes on a one square centimeter sieve. In fact, the textbook "Mineralogy" clearly defines the Taylor standard "mesh" in the United States, which refers to the number of mesh holes on a 1-inch sieve. At present, this standard is generally adopted internationally, and China is no exception. The standard sieves currently available on the market are all manufactured based on the Taylor standard.

2. Taylor standard sieve calculation, based on 200 mesh=0.074mm,Main modulus,Form a secondary mold tear standard sieve. Multiply or divide the 0.074 modulus to obtain the mesh size of the main and auxiliary series standard sieves. We usually need to remember the correspondence between commonly used mesh size and particle size.

3. The concept of purpose comes from the sieve, which has mesh wires. Due to manufacturing processes, mesh wires cannot be infinitely fine, which means that in reality, large mesh numbers only exist in calculations and there is no standard sieve material. At present, the standard sieve with the largest mesh size can be seen on the market. So what exactly are the 1250 mesh, 2500 mesh, or even 5000 mesh powders we're talking about? Usually, we can use 14400/particle size to roughly calculate the mesh size of particles.

5. We often hear about the fineness of a powder and how it is obtained? In theory, this statement is not scientific and accurate, and there is also a problem in practice. It is claimed that powders with the same mesh size may have significantly different particle size distributions, although exaggeration cannot be ruled out. Regarding this issue, we can use the particle size distribution mentioned earlier to calculate. The mesh size is a specific numerical value, for example, 400 mesh is 38um. So, when naming this powder, is it d50 or d97? In mineralogy textbooks in our country, this issue is clearly defined as the fineness of the powder corresponding to the mesh size of the sieve when the content on the sieve is not greater than 2%. This conversion to particle size distribution is understood as d98.

6. Source of popular powder mesh: In the 1990s, with the development of the plastic and coating industries, inorganic non-metallic powders became an emerging industry, and many people entered the powder processing industry. At that time, the most commonly used equipment in small factories was the Raymond machine of the rotary classifier, and there were not many or even no testing methods and instruments. Mining enterprises use ball mills for dry grinding, and the mining industry usually checks and controls the grinding situation based on a 200 mesh content. The Raymond mill was a dry grinding equipment capable of finely grinding to 325 mesh at that time. Therefore, when the parameters of the Raymond machine are at the optimal position, the manufacturer considers it to be 325 mesh. When the parameters are increased, it becomes 400 mesh, and the limit parameter is 500 mesh. Therefore, Raymond's production products are defined as having a mesh size. The appearance of vertical grinding and air flow grinding in the later stage is also similar, for example, some people often say what is true 1250 mesh and false 1250 mesh? The early vertical mill without modification was believed to produce 800 mesh powder, with a limit of 1000-1250 mesh. In summary, it is the combination of production capacity promoted by equipment manufacturers and user estimates that gave rise to the concept of powder mesh size.

Suggestion: For regular powder production, it is recommended to use particle size distribution to characterize the fineness of the powder with the least ambiguity.