The diameter of flat burrs in coffee grinders directly determines grinding efficiency, particle uniformity, and application scenarios — smaller burrs are more suitable for small-batch, precision-controlled grinding, while larger burrs tend to handle high-load, large-scale operations. The "shear grinding" characteristic of flat burrs exhibits differentiated advantages across different sizes: small-sized burrs focus on fineness, while large-sized burrs prioritize stability and productivity. Below is a detailed analysis of five mainstream sizes: 40mm, 54mm, 60mm, 64mm, and 65mm.