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What is Roller Shells? The guide to Roller Shells.

May. 06, 2024

What is  Roller Shells?

Roller shells are a vital component of pellet mills and other biomass processing equipment. They are designed to facilitate the pelletizing or granulating process by providing a smooth and efficient surface for material compression. Roller shells are typically cylindrical in shape and made from high-quality materials to withstand the demanding forces and abrasion encountered during operation.

The main function of roller shells is to squeeze bio-mass materials or feedstock against a die or ring to form dense pellets or granules. As the rotating rollers press against the stationary die, the material is compacted, creating pressure and heat that helps bind the particles together. This process is known as pelletizing or granulating.

Roller shells consist of several key components:

Part I : The central part of the roller shell, which is mounted on a rotating shaft connected to the motor or drive mechanism of the pellet mill.

Part I I: The cylindrical outer surface of the roller shell, where the material is compressed against the die. The shell is typically made from durable materials such as alloy steel, stainless steel, or carbon steel.

Part I II: Roller shells may feature chamfers or specific hole patterns to aid in material flow and enhance pellet formation.

To ensure optimal performance, roller shells need to possess certain qualities such as high wear resistance, excellent dimensional accuracy, and compatibility with the specific pellet mill or biomass processing equipment. They should also be able to withstand high torque levels and exhibit minimal deformation during operation.Roller shells can experience wear over time due to the abrasive nature of the pelletizing process. When wear occurs, regrinding or replacement of the roller shells may be necessary to maintain their performance and efficiency.In summary, roller shells are an essential component of pellet mills and other biomass processing equipment. They provide the necessary surface for compressing bio-mass materials into pellets or granules and are made from durable materials to withstand the forces encountered during operation. Quality roller shells contribute to efficient and reliable pellet production.

Roller Shells

Pellet mill roller shell CPM 7000 SW

Pellet mill roller shell CPM 7000

Pellet mill roller shell CPM 7722

The Guide to Roller Shells

Roller shells play a crucial role in the efficient operation of pellet mills and other biomass processing equipment. As a leading company in the industry, BOBSHELL takes pride in manufacturing high-quality roller shells that are known for their durability and performance. In this guide, we will explore various aspects of roller shells, including staff training, our advantages, the shell manufacturing process, shell regrinding, roller shell torque, and dimensional tolerances.

PartⅠ: At BOBSHELL, we believe that well-trained staff is essential for delivering exceptional roller shells. Our team undergoes comprehensive training to ensure they have the knowledge and skills required to manufacture top-quality roller shells. By investing in staff training, we maintain a high level of expertise and ensure consistent quality throughout the production process.

PartⅡ: BOBSHELL stands out in the industry for several reasons. One of our key advantages is our commitment to quality. We utilize premium materials and employ advanced manufacturing techniques to create roller shells that are highly durable and efficient. Additionally, we offer outstanding customer service, providing prompt support and guidance to our clients. Our dedication to quality and customer satisfaction sets us apart from the competition.

PartⅢ: The manufacturing process of roller shells at BOBSHELL involves several critical steps. It begins with the selection of high-quality raw materials, ensuring optimal performance and longevity. The shells are then precision machined and heat-treated to enhance their hardness and resistance to wear. Advanced technologies, such as CNC machining and specialized coating applications, are employed to optimize the performance of the roller shells.

PartⅣ: Over time, roller shells may experience wear due to the abrasive nature of the pelletizing process. At BOBSHELL, we understand the importance of prolonging the lifespan of our roller shells. We offer shell regrinding services, where worn-out shells are carefully reconditioned to restore their original dimensions and performance. This cost-effective solution allows our customers to extend the service life of their roller shells, minimizing downtime and replacement costs.

PartⅤ: The torque capability of roller shells is a critical factor in their performance. BOBSHELL roller shells are designed to withstand high torque levels, ensuring smooth and efficient pellet production. The robust construction and high-quality materials used in our roller shells provide excellent torque transfer and minimize the risk of slippage or damage during operation.

PartⅥ: Precision manufacturing is vital for roller shells to maintain optimal performance. At BOBSHELL, we adhere to strict dimensional tolerances during the production process. This ensures that our roller shells meet the required specifications and fit seamlessly with the pellet mill or biomass processing equipment. Accurate dimensional tolerances contribute to the efficient operation and longevity of roller shells.

In conclusion, BOBSHELL roller shells are manufactured with meticulous attention to detail and a commitment to quality. With trained staff, advanced manufacturing processes, shell regrinding services, and superior torque capabilities, our roller shells deliver exceptional performance and durability. The strict adherence to dimensional tolerances guarantees a seamless fit with pellet mills and biomass processing equipment. Trust BOBSHELL for reliable roller shells that optimize the efficiency and productivity of your operations.

What is the difference between Roller Shells and Ring Die?

Roller shells and ring dies are both essential components of pellet mills used in biomass processing. Although they serve similar purposes in the pelletizing process, there are key differences between them.

Structure and Design:

Roller Shells: Roller shells are cylindrical components that rotate against a stationary ring die. They typically feature a smooth or textured surface for compressing the biomass material against the die.

Ring Dies: Ring dies, on the other hand, are stationary and surround the rotating roller shells. They have multiple holes or perforations through which the compressed material is forced to form pellets. The specific hole pattern on the ring die determines the size, shape, and density of the pellets produced.


Roller Shells: Roller shells primarily function to squeeze the material against the ring die, creating pressure and heat that aid in pellet formation. The rotating motion of the roller shells enables the material to be compacted and forced through the holes in the ring die.

Ring Dies: Ring dies provide the shaping and compression necessary to transform the raw biomass material into pellets. The design and configuration of the holes in the ring die dictate the size and characteristics of the pellets produced.

Manufacturing Complexity and Cost:

Roller Shells: Roller shells are generally simpler in design and manufacture compared to ring dies. They usually consist of a single cylindrical component, which can offer cost advantages in terms of production and replacement.

Ring Dies: Ring dies tend to be more complex and require precision manufacturing with multiple holes or perforations. The intricate design and manufacturing process of ring dies can result in higher production costs.


Roller Shells: Roller shells are commonly used in pellet mills where smaller quantities or specialized types of pellets are required. They are suitable for applications with lower production volumes and specific pellet requirements.

Ring Dies: Ring dies are typically employed in larger-scale pellet mills that require high production capacities. They are used for producing a wide range of pellets, including animal feed, wood pellets, and various biomass pellets.

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