The compression ratio of the pellet machine mold affects the output and quality of the pellets

Compression ratio of pellet machine mold

The compression ratio of a pellet machine mold refers to the ratio of the effective length of the die hole to the diameter of the die and is an indicator of the extrusion strength of the pellet machine.

Mold compression ratio of pelletizing machine = mold hole diameter / effective working length of mold hole

For a die with a straight hole, the effective length of the die hole is the total thickness of the die, and the small diameter is the diameter of the die hole itself.

Assumption: The diameter of the die hole is 6mm and the thickness of the ring die is 45mm.

• Compression ratio = 6/45 = 1: 7.5
• The ring mode compression ratio is 1:7.5

For step hole and outer taper hole, the effective length of the die hole is the total thickness of the die minus the length of the release hole or the length of the outer taper and the opening of the small diameter section is the aperture for calculation. compression ratio.

Assumption: diameter of ring die hole is 8mm, die thickness is 66mm and release hole is 18mm

• Compression ratio = 8 / (66-18) = 1: 6
• The ring mode compression ratio is 1:6

Compression ratio is a ratio. For the same compression ratio, its effective aperture and working length may be different.

How to choose the right mold compression ratio

1. The aperture and outlet size of the die is closely related to the inner diameter of the pellet machine mold and the composition of the raw material. Standard apertures of 8-10 mm are commonly used in the so-called conventional data industry. Pellet presses larger than 10 mm require greater pressure for molding. Relatively speaking, the wear and tear is also large, users call it biomass stick making machine or stick making machine.

2. The effective thickness of the mold is very important for the material molding process. If the mold is too thick, the material casting time is longer, the particle density is relatively large, the extrusion is more difficult, the mold is thin and fragile, and the particle density is relatively small. . Low pressing temperature, high output but low pressing rate or poor molding.

3. The compression ratio of the abrasive tool is determined according to the raw material. The compression ratio of poplar is 1:6, the compression ratio of pine is 1:7, the compression ratio of hardwood is 1:5, and the compression ratio of shavings is 1:5.5, the compression ratio of corn stalks is 1:6.5. From these simple numbers, the compression ratio of different raw materials is different. The harder the raw material, the smaller the compression ratio, and the finer the raw material, the larger the compression ratio. That is, the finer the raw material, the easier it is to mold. Finer raw materials contain more fibers and materials containing more fibers are easier to form.

4. Each direct small hole has 6mm, 8mm and 10mm. This 1 represents the diameter of each small hole. If the diameter of the ring die hole is 8 mm, then the value 1 represents 8, and 6 represents the effective aperture. The effective aperture is the diameter of the hole times the effective aperture length, which is 6 * 8 = 48, which is 8:48, 8:48 is simplified to 1:6, 1:6 is the compression ratio of Birch. It is converted this way. The output quality of the biomass pellet machine depends on the compression ratio of the ring die. But if the customer does not have a high requirement for your pelletizing ratio, then you can reduce the compression ratio appropriately, which can not only increase the output, but also reduce the life of the mold and the cake. squeeze.

5. Roughness is also an important criterion to measure the quality of the stamping die. In the same compression ratio, the larger the roughness value, the greater the extrusion resistance of the sawdust particles, and the harder it is for the material to discharge. Excessive roughness also affects the grain surface quality. The appropriate roughness value should be 0.8-1.6. Between.

What to do if the mold compression ratio is too large?

1. The experienced operator will adjust the moisture content of the raw material or adjust the distance between the ring casting rollers, and the pellets can be discharged smoothly without changing the compression ratio. This process should be documented and checked every step of the way.

2. In addition, the second pressurization can make the die with a larger compression ratio smaller, but adjusting the ring mold will affect the hardness of the ring die, so it should be determined according to the actual wear of the ring die. mold.

The roughness of the die hole of the pellet machine is also an important parameter to measure the quality of the mold, and the appropriate roughness value should be in the range of 0.8-1.6. In the same compression ratio, the larger the roughness value, the greater the grain extrusion resistance and the harder it is for the material to discharge. Excessive roughness also affects the grain surface quality. If you have any doubts about using the mold, please leave a message to discuss.

Refer to the installation process of the export wood pellet factory of GREEN MECH

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