Compression ratio is the ratio between effective length and hole diameter of the ring die, which is used to show the index of pellet mill compressive strength.
Compression ratio=hole size of ring die/effective length of hole channel
Different hole shape owns different calculating mentions for compression ratio.
For the straight hole ring die, the effective length is
same as the complete thickness, and min. diameter is the hole size of the ring die.
If the hole size is 4.0mm, and thickness is 50mm.
Compression ratio=4.0:50, comes 1:12.5, and the compression ratio for this die is 1:12.5
For release type step hole and taper hole, the effective length is the total thickness minus step hole length or taper hole length, min. hole diameter is the hole size used to calculate the compression ratio.
If the hole size is 2.0mm, thickness is 38mm, step hole is 3mm.
Compression ratio=2.0:(38-3), comes 1:17.5, and the compression ratio for this die is 1:17.5.
Note: compression ratio is only a ratio, the effective length and hole size for same compression ratio will be different.