The fibre refiner mill is one of the main equipment on the density board production line, and the quality of the fibers directly affects the final quality of the density board. To produce good fibers from a refiner mill, at least three aspects of work must be done well: possessing a scientific design concept, achieving manufacturing accuracy according to design requirements, and having a user who understands and loves it.

1.  Design concept of hot refiner mill

There is a common saying that goes "a problem in the fetus". When encountering this disease, one must either return to the furnace or undergo major surgery, and there is no other way. What is a 'problem in the tire'? In terms of refiner mills, it mostly refers to the design concept being faulty. A scientific design concept is particularly important for refiner mills, especially those larger than 48 inches, to have a foundation for producing good fibers.

At present, there are two mainstream design concepts for large-scale refiner mills in the industry. One is the design concept that pursues "constant power" operation of refiner mills as the main goal, represented by Germany's Perlman and Finland's Metso (including the old Sands refiner mill); Another approach is to pursue the "constant clearance" operation of the refiner mill as the main goal, represented by Austria's Andretz.

The refiner mill designed by the "constant power" school has a relatively stable current of the main motor of the refiner mill under normal operation. The initial means to achieve "constant power" is to change the gap between the moving and stationary disks through the expansion and contraction of the oil cylinder stroke. The negative impact of this method is to cause changes in fiber thickness. How to eliminate this negative impact is a challenge to the "constant power" genre, and we have seen some thermal mill manufacturers make breakthroughs in this regard.

The refiner mill designed by the "constant clearance" school maintains the gap between the moving and stationary discs of the refiner mill under normal operation through mechanical limit devices. This method can cause greater current fluctuations in the main motor of the refiner mill when the feed is uneven, the size of the wood chips is uneven, or the cooking is uneven. In addition, if hard substances such as iron enter, the impact damage to the grinding disc and spindle system is relatively greater. Faced with this negative characteristic, some refiner mill manufacturers have started to increase their response devices to emergencies, with the aim of reducing the degree of damage to the refiner mill.

In actual operation, the user's expectation for a refiner mill is both "constant power" and "constant clearance". Constant power and clearance "is the ideal and ultimate goal of refiner mill designers.

Can the "constant power and clearance" state of the refiner mill be achieved in actual operation? After a long period of research, exploration, and practice, the refiner mill designers of Jiecheng Company have provided a positive answer. We achieve the goal of constant power and clearance by ensuring the uniformity of chip size, cooking, and the amount of wood chips entering the grinding entity. This involves the design of a new structure for the refiner mill and the precise control of chip quality and steam flow by users.

In contact with customers, it is often mentioned whether the refiner mill saves electricity. To obtain scientific answers, it is necessary to clarify two main questions: what design structure of the refiner mill can save electricity? How can a refiner mill be used to save electricity?

2. Manufacturing accuracy of refiner mills

With the scientific design concept of refiner mills, it only ensures that the development of refiner mills will not go astray. The functionality and design accuracy of refiner mills are still achieved through manufacturing and assembly accuracy.

Users often ask: What are the differences between domestic and imported refiner mills? I know this is not a question that can be answered clearly in a few words, but I also know that it is not a problem that Chinese enterprises cannot solve in three to five years.

Manufacturing accuracy is no longer a problem for Chinese refiner mill manufacturing enterprises with high-precision CNC equipment. The problem is how to maintain stability, non loss, and interchangeability of accuracy.

For example, it takes eight months for users to purchase imported mills, while domestic mills only accept a delivery time of four to five months. This is the problem. Our refiner  mill manufacturing company can indeed manufacture a refiner mill within a four month cycle, but the stress relief process of the refiner mill body can only be achieved through tempering, which has a significantly different effect from long-term aging treatment.

The 50 inch refiner mill body (near the grinding chamber body) undergoes a size change of about 4 millimeters during shutdown and operation. How to ensure operating accuracy cannot be guaranteed solely by manufacturing accuracy.

3. Correct use of refiner mills

As the saying goes, 'three devices are used for seven purposes', indicating the importance of usage. At present, Jiecheng has become a large-scale refiner mill provided by the market, and has placed great emphasis on electrical interlocking, steam balance, and other process related configurations, which can meet the requirements for producing good fibers.

Kung Fu is beyond poetry. If you add 90 octane gasoline to a Mercedes Benz car, the engine may not perform well for you. The quality of wood chips is the key to grinding fibers, mainly manifested in the following factors: differences in tree species of wood chips (differences in softness and hardness can affect fiber quality), the size and uniformity of moisture content of wood chips, the sediment content of wood chips, and the metal content inside the wood chips. The selection of grinding discs is also very important, whether the tooth shape of the grinding disc is suitable for the characteristics of the raw material, the dynamic balance accuracy of the grinding disc, and its own toughness. The stability of steam flow rate and the effect of wood chip pre cooking are also influencing factors.