Grading by coffee bean size is a standard measure for the coffee industry. In, coffee beans, after preliminary processing, will be rayed through perforated metal plates with different diameters from 8 to 20/64 inches for classification.
Sieve size from 8 to 20, sieve size in the scale of 1/64 inch. Sieve 18 means 18/64 inch, measuring unit of mm is 7.1mm, similarly sieve 16 is converted to 6.3mm.
To serve the needs of processing and mass production, people use sieving machines to sort the size of coffee beans. Vibration speed and large capacity vibration amplitude can make 12-14 tons of bucket material/per hour.
However, the classification of coffee bean size can hardly be 100% accurate. For example, some particles, although small, do not fall due to the high density. So in its grading system, the SCA allows a 5% difference from the sieve measurements (that is, out of 100 coffee beans on sieve 18, there are permitted five smaller or larger beans).
The larger the volume, the longer it takes to cook with cooking potatoes. Or when between different large and small potatoes, they will ripen unevenly. The same goes for coffee beans; the more significant the roast, the longer the roasting process takes, so before roasting, we must ensure that each batch of coffee has an actual size of the kernels to help the roasting process be consistent and thus better product quality.