कंपनी की खबर Key Points for Biomass Granulator Knife Selection: How to Handle High-Wear Working Conditions of Straw and Wood Chips?

Biomass granulation (straw, wood chips, rice husk, etc.) is a core link in new energy utilization, and high wear is the most prominent problem faced by granulator knives in this field. Straw contains silica, wood chips are often mixed with sand particles, and coupled with the high-fiber characteristics of the materials, ordinary granulator knives will quickly experience edge blunting, chipping, and other issues, seriously affecting production efficiency and costs. Due to its ultra-high hardness (HRA≥90) and wear resistance, tungsten carbide has become the preferred material for biomass granulator knives, but improper selection will still lead to "insufficient durability". Focusing on two mainstream biomass materials—straw and wood chips—this article uses plain language and clear tables to break down key selection points from the analysis of high-wear causes, tungsten carbide granulator knife selection parameters, and targeted solutions, helping industry practitioners accurately match needs and effectively handle high-wear working conditions.

The high-wear characteristics of biomass materials are not caused by a single factor, but by the combined effect of material properties, impurities, structure, and other aspects. Only by clarifying the root causes can we select knives in a targeted manner:

• Silica and Sand Particle Abrasion: Straw (especially corn straw and wheat straw) contains 2-5% silica, and wood chips are often mixed with soil sand particles. Silica and sand particles have a hardness close to quartz (Mohs hardness 7), which will continuously grind the granulator knife edge, leading to rapid blunting;
• High-Fiber Tensile Wear: The fiber content of straw and wood chips is as high as 60-80%. During granulation, fibers will wrap around the edge and generate strong tensile force, exacerbating edge wear. At the same time, heat generated by fiber friction will cause material adhesion, further worsening the wear environment;
• Impact of Material Humidity Fluctuations: Biomass humidity (10-30%) varies greatly. High humidity causes materials to stick and block the machine, while low humidity makes materials dry and loose with stronger abrasiveness, requiring higher adaptability of granulator knives;
• Hard Spot Impact Wear: Wood chips may contain branch knots, and straw may have withered leaf stems and other hard spots. During granulation, these hard spots will cause instantaneous impact on the edge, leading to micro-chipping, which will reduce the service life of the knife over time.

Targeting the high-wear characteristics of biomass, the selection of tungsten carbide granulator knives should focus on three core dimensions: "material formula, edge structure, and knife body design", each with clear adaptation standards:

The material formula of tungsten carbide (cobalt content, grain size) directly determines wear resistance and impact resistance, which is the foundation for handling high wear:

The edge is the part directly in contact with materials, and its structural design must specifically address the abrasion and winding problems of biomass:

• Edge Angle: 35-45° (35-40° for straw, 40-45° for wood chips). A larger angle enhances edge strength, reduces chipping from hard spot impacts, and lowers the probability of fiber winding;
• Edge Shape: Serrated edge (tooth pitch 3-5mm) + micro-chamfer (0.3-0.5mm). The serrated edge can quickly cut fibers to avoid winding, and the micro-chamfer disperses stress to improve impact resistance;
• Surface Treatment: Mirror polishing (Ra≤0.2μm) + nitriding treatment. Polishing reduces material adhesion, and nitriding treatment increases the surface hardness of the edge (HRA≥92) to enhance wear resistance.

The knife body structure must provide sufficient support for the edge and adapt to the working characteristics of biomass granulators:

• Knife Body Thickness: ≥12mm (straw granulation) / ≥14mm (wood chip granulation). A thickened knife body improves overall rigidity, avoiding knife body deformation during high-load cutting;
• Tip Fixation Method: Embedded tip (welding + mechanical clamping). Biomass granulation has high impact loads; the embedded design is more impact-resistant than the integral type, and the tip can be replaced individually after wear, reducing maintenance costs;
• Chip Removal/Heat Dissipation Design: The knife body is equipped with chip removal grooves (width 5-8mm), and straw granulator knives are additionally equipped with heat dissipation grooves. Chip removal grooves can quickly discharge fiber debris, and heat dissipation grooves reduce frictional heat generation to minimize material adhesion.

Combined with the above analysis, exclusive selection schemes for the two types of materials are sorted out, covering core parameters, applicable scenarios, and expected effects for direct reference:

• Adjustment for high-impurity scenarios: If the silica content of straw exceeds 5% or the sand particle content of wood chips exceeds 3%, upgrade to YG12 grade (high cobalt, high wear resistance) and thicken the edge to 2.5mm to further improve wear resistance;
• Adjustment for high-humidity scenarios: When humidity exceeds 25%, straw granulator knives can be added with PTFE anti-adhesion coating to reduce additional wear caused by material adhesion;
• Adaptation for low-output scenarios: For daily output <5 tons, conventional thickness knife bodies (10-12mm) can be selected to reduce procurement costs while ensuring basic durability.

• Mistake 1: Blindly pursuing high hardness and selecting low-cobalt grades (e.g., YG6) → Insufficient toughness, prone to edge chipping from straw stems and wood chip knots;
• Mistake 2: Edge angle too small (≤30°) → Sharp edge but insufficient strength, prone to edge rolling and chipping after long-term grinding;
• Mistake 3: Selecting integral tungsten carbide granulator knives → Biomass granulation has high impact, and the integral type has weak impact resistance, prone to knife body fracture;
• Mistake 4: Neglecting surface treatment → Knives without polishing/nitriding treatment have severe material adhesion, exacerbating wear and blockage.

• Installation Gap: Control the gap between the granulator knife and fixed knife at 0.2-0.4mm. Excessively large gaps cause excessive fiber tension, while excessively small gaps increase frictional wear;
• Daily Maintenance: Clean residual fibers and impurities on the edge after daily operation, check edge wear weekly, and perform precision grinding (maintaining the original angle) when slight blunting occurs;
• Material Pretreatment: Crush straw to ≤5mm before granulation to remove hard stems; screen wood chips to remove large sand particles before granulation, reducing impurity abrasion.

To handle the high-wear working conditions of straw and wood chips, the selection of tungsten carbide granulator knives does not require complex calculations. The core is to grasp three key points: "material formula balances hardness and toughness, edge structure resists wear and winding, and knife body design strengthens support". Straw granulation focuses on anti-winding and heat dissipation, while wood chip granulation emphasizes resistance to hard spot impacts and sand particle abrasion.

As a tungsten carbide industry practitioner, we can provide customized granulator knife solutions based on the characteristics of different biomass materials—from tungsten carbide grade adjustment, edge structure design to knife body strengthening, fully adapting to high-wear working conditions. If you need precise selection advice based on specific materials (e.g., special straw, high-impurity wood chips), granulator parameters, or output requirements, please contact us to help improve biomass granulation efficiency and reduce knife replacement costs!