how to avoid pellet machine ring die crack

How to avoid pellet machine ring die crack?

In biomass pellet making industry, the ring die is the most important wear parts of pellet machine, no matter vertical ring die pellet machine or horizontal ring die pellet machine. The ring die matters the whole pellet production efficiency and biomass pellets quality. But the pellet machine ring die cracking problem always happen, this will not lead the pellet machine shut down, and increase the whole pellet making cost. Today we will give you some reasons about the pellet machine ring die cracking and some measures to avoid this problem.

Reasons for ring die cracking

ring die crack

Mechanical wear

Roller and ring die wear

With the time running, the surfaces of the press roller and the ring die will gradually wear, leading to uneven pressure on the ring die.

Transmission key wear

The transmission key gradually wears down due to friction and pressure over prolonged use.

Shaft jumping and bearing damage

The Slight runout of the main shaft and bearing damages will cause stress concentration on the ring die, increasing the risk of cracking.

Improper Installation and Operation

Incorrect Roller Installation:

If the rollers are not installed correctly, they can cause uneven pressure and stress on the ring die.

Inadequate Roller-Ring Die Gap Adjustment:

The ring die and roller should keep at suitable distance, the gap should not be too small ,or too big. The perfect situation is that the roller shell just touch the ring die surface , and the roller can rotate freely. Too stress will make the roller shell and ring die break easily, if the gap is too big, it can not good quality pellets.

Forget to Clean Die Holes During Shutdown:

ring die holes block

Every pellet machine shut down, the correct practice is to clean the ring die holes with oil raw material, this can make sure the ring die can make good quality pellets when next operation. If you forget to clean the ring die holes, the dry raw materials will stuck inside the ring die holes, which will bring damage to the ring die, and when you start the pellet machine next time, you need to spend quite long time to make pellets smoothly.

Using Hard Steel Tools to Replace the Ring Die:

This always happen when you replace the ring die, the workers will use hammers to replace the ring die, this will bring quite big damage to the ring die also.

Raw Material Reasons

High Content of Sand or Iron Impurities:

If your raw materials contains a lot of sand or iron impurities, this will bring direct damage to the ring die. Especially when you process agricultural raw materials, like corn straw, rice straw, and construction plywood, which contains a lot iron nails. You need to add one rotary screener ,to sort out the stone and sand, and one magnetic iron remover to remove the nails inside. This can make sure the ring die and roller achieve higher lifetime .

Crude fiber raw materials

If you want to make biomass pellets with high content fiber, for example rice straw, corn stalk, bagasse, sugarcane leaves etc, you need to process them into fine size, then feed to the pellet machine to make pellets, if the raw materials contains too long fiber, this will add pressure of the ring die, and bring the ring die cracking problem.

Ring Die Bad Quality

Material Fatigue:

After overtime working, the ring die will wear out because of fatigue, and then crack.

Improper Heat Treatment:

Each ring die will go through several heat treatment before shaped, if incorrect heat treatment, the inside structure will become very fragile, this will bring the ring die crack problem.

Inappropriate Compression Ratio and Opening Rate:

The inappropriate compression ratio and opening rate, will increase the burden of the ring die, and lead the ring die crack.

Methods to Prevent Ring Die Cracking

Choosing the Right Ring Die

Different Raw Materials use Different Ring die

Because of the natural factor, different raw material need different ring die, you can not use one ring die to process various raw materials, even same raw material, different growing situation will lead to the different raw material density, it also need to use different ring die to process.

Optimizing Feeding and Operation

Ensure Even Feeding:

Feeding the raw materials based on the electric current amp and adjust it when needed, don’t over loading, this will bring irreversible harms.

Adjust Roller-Ring Die Gap Timely:

Because of the conflict of the roller and ring die, the distance between the roller and ring die will increase, you should regularly check the gaps and adjust it when needed. The check should be performed daily.

Debris Removal and Maintenance

Install Iron Removal Devices:

Before the raw materials feeding into pellet machine, make sure all the raw materials go through the iron magnetic removers, to remove the iron or nails inside the raw material, this is the quite big harm elements for ring die, especially for the wood pallet and construction raw materials.

Store Ring Die Properly:

Keep the ring die in a dry and ventilated place to avoid rust and corrosion. And also avoid the ring dies collision.

Purchasing and Storage

Choose From Reliable Ring Die Suppliers

Choose ring dies from verified suppliers, you should know the process for manufacturing ring die, and you will see why there are so many suppliers selling with different price. For manufacturing ring die, each steps matters, you can not avoid any steps.


Above are our analysis for the ring die cracking and measures to avoid this problem, hope this can help you solve your pellet machine ring die problems, if you have other questions about pellet making, welcome to discuss with us .

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