Description

Among various groove designs for pellet mill rollers, the No oblique slot roller shell represents a traditional and classic solution that remains irreplaceable in many pelleting applications. A No oblique slot roller shell refers to a roller whose working surface grooves are inclined but non-continuous, featuring interruptions, closed ends, or spiral termination points. Material cannot be fully discharged axially along the grooves; instead, it undergoes repeated kneading and compression within the grooves before being released laterally or at the groove ends.

The No oblique slot roller shell has long been recognized by the market and widely used in specific fields due to the following core advantages:

First, the strongest kneading and shearing action on materials. Because the grooves are non-continuous and inclined, material cannot be discharged directly along the grooves. Instead, it is repeatedly kneaded, folded, and sheared during roller rotation. This intense mechanical action effectively breaks down the waxy surface layer and fiber structure of the material, significantly improving its binding properties and plasticity. This makes it especially suitable for high-fiber, high-lignin, or smooth-surfaced materials that are difficult to form, such as rice husks, peanut shells, cotton stalks, and coffee grounds.

Second, the highest pellet density and best durability. Material undergoes multiple compressions and extended residence time within the non-continuous inclined grooves, resulting in a compression ratio far higher than that of straight-through or through-oblique slot designs. This produces pellets with extremely smooth surfaces, high density, and high hardness, which are less prone to powdering during transportation, storage, and use, and offer strong resistance to breakage. This characteristic is particularly critical for high-quality biomass fuel pellets and premium feed pellets.

Third, suitable for low-speed, high-compression-ratio production processes. No oblique slot roller shells are typically used with low-speed pellet mills, exchanging longer material residence time in the compression zone for higher forming density. Although this process yields relatively lower single-machine output, the pellet quality is excellent, making it suitable for producing high-value-added products such as export-grade biomass pellets and specialty aquafeed pellets.

In terms of material and process, high-quality No oblique slot roller shells are manufactured from high-alloy steel or carburized bearing steel (e.g., 20CrMnTi, GCr15) through forging, carburizing, overall quenching, and low-temperature tempering. The working layer hardness reaches HRC58-62, while the core maintains good toughness. Since the non-continuous inclined groove structure subjects the roller to more complex stresses during operation, higher demands are placed on the material’s fatigue resistance. Premium products often incorporate cryogenic treatment or surface shot peening for reinforcement.

Regarding compatibility, No oblique slot roller shells can be customized with inner hole diameter, keyway, roller width, groove depth, groove width, groove pitch, inclination angle, and interruption positions according to original mill specifications. They are compatible with both ring-die and flat-die pellet mills and fit major brands worldwide.

It should be noted that No oblique slot roller shells also have disadvantages, including relatively slower discharge, average heat dissipation performance, and greater cleaning difficulty. Therefore, selection should involve a comprehensive trade-off based on material characteristics and production goals.

In summary, with its extremely strong kneading capability, highest pellet density, and excellent adaptability to difficult-to-form materials, the No oblique slot roller shell maintains an important application position in the production of high-quality biomass pellets and specialty feed pellets.

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