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Views: 12 Author: Site Editor Publish Time: 2024-01-23 Origin: Site
In the solid waste recycling industry, the double-shaft shredder, as the core crushing equipment at the front end, has its operating efficiency, maintenance costs, and even the overall service life directly determined by the choice of blades. How to choose double-shaft shredder blades becomes a core issue. Incorrect selection will not only lead to rapid blade wear and uneven crushing particle size, but also cause soaring energy consumption and frequent downtime. Mainstream double-shaft shredders adopt a 5.5–10 rpm low-speed, high-torque design, which places stringent demands on the wear resistance, impact resistance, and structural stability of the blades. The precise matching of double-shaft shredder blade material selection with working conditions is the key to solving all these problems.
The principle for choosing double-shaft shredder blades is not simply "the better the material, the better blade," but rather a combination of material characteristics + equipment parameters + production capacity targets. This is also the key to avoiding excessive blade wear and cost waste.
1. Clarify the material to be processed: The hardness, impurity content, and moisture content of the material are the primary basis for selection. For example, construction waste containing sand and mud requires strong impact resistance, metal scraps require high wear resistance, and soft fibrous materials require sharp cutting edges;
2. Equipment parameters: Based on the shredder model, blade shaft diameter, number of blades installed, and spindle torque, select the appropriate blade thickness, number of teeth, and installation structure;
3. Determine production capacity and output requirements: Fine-grained output requires blades with a high number of teeth, high-load continuous operation requires special steel materials with superior comprehensive performance, and coarse crushing of large materials prioritizes blade throughput and impact resistance.
Material is the core performance carrier of double-shaft shredder blades, and different materials have significantly different wear resistance, impact resistance, and heat treatment characteristics:
The core advantage of high manganese steel blades is high toughness and strong impact resistance. After being impacted by materials, work hardening occurs, and the surface hardness increases significantly, enabling it to withstand the abrasion of impurities such as mud and gravel.
Suitable materials: Municipal solid waste, construction waste, landfill screen rejects, industrial waste containing mud and sand. These materials have many impurities and strong impact characteristics.
9CrSi blades have high hardness, sharp edges, and good wear resistance. The processing technology is mature, and the purchase cost is much lower than cold work die steel. The disadvantage is that it is slightly brittle and has average impact resistance, making it unsuitable for processing materials containing hard impurities.
Suitable materials: Rubber, paper, fiber, PE/PP film, woven bags, and other soft solid waste. These materials have no hard impurities, require low impact resistance from the blades, and prioritize sharpness and shearing efficiency.
Cr12MoV and SKD-11 shredder blades are currently the mainstream choice in the solid waste recycling industry. Both have strong wear resistance, excellent impact resistance, and low heat treatment deformation. They maintain excellent edge retention, and after quenching + low-temperature freezing treatment, the hardness can reach HRC 58–62, resulting in a much longer service life than 9CrSi. • Cr12MoV: High cost-effectiveness, a mainstream domestic material, suitable for most medium-to-high hardness materials, and the preferred choice for small and medium-sized solid waste projects;
• SKD-11: Superior wear resistance, suitable for high-strength materials such as metal scraps and hard plastics, widely used in export projects;
Suitable materials: Wood, waste furniture, hard plastics, metal scraps, electronic waste, paint cans, PE pipes, and other medium-to-high hardness materials, making it a "universal material" in the solid waste recycling industry.
H13 special steel shredder blades and high-speed steel materials possess excellent comprehensive properties including wear resistance, impact resistance, and high-temperature resistance. The blades have high overall strength and are not prone to cracking or deformation, making them suitable for heavy-duty industrial solid waste projects requiring ultra-long continuous operation.
Suitable materials: Scrap steel, large car shells, heavy industrial mixed waste, and other ultra-high hardness materials. These scenarios demand extreme blade performance and are suitable for large solid waste treatment enterprises with high production capacity requirements.
After determining the material, the structural parameters of the blade directly affect the crushing efficiency, output particle size, and subsequent maintenance efficiency. The core parameters to consider are the number of claws, thickness, and installation structure, all of which need to be precisely matched to the equipment and output requirements:
Dual-shaft shredder blades all have a claw-type structure. The number of claws on a claw-type shredder blade is inversely proportional to the output particle size and directly proportional to the throughput. The mainstream options are 2 claws, 3 claws, 6 claws, 8 claws, and 12 claws. The selection principle is simple and straightforward:
• 2 claws / 3 claws: Excellent throughput, suitable for coarse crushing of large, ultra-hard materials, such as whole tires, large metal parts, and large pieces of waste. The output particle size is relatively coarse;
• 6 claws / 8 claws: Balances throughput and crushing efficiency, suitable for most solid waste materials, and is the mainstream choice in the industry. The output particle size is uniform;
• 12 claws: High shearing frequency, resulting in extremely fine output particle size, suitable for scenarios with strict requirements on crushing particle size, such as pre-crushing before plastic recycling and granulation. The disadvantage is that the throughput is poor, and jamming is more likely. •
H3: Blade Thickness Selection Determines Impact Resistance and Shear Force
Shredder blade thickness ranges from 10mm to 75mm. The core principle for selecting shredder blade thickness is that "the harder the material, the thicker the blade." Thickness directly determines the blade's impact resistance and load-bearing capacity:
• 10mm/20mm: Suitable for soft materials such as rubber, paper, and film; sharp cutting edge and high shearing efficiency;
• 30mm/40mm: Suitable for medium-hardness materials such as wood, ordinary plastics, and household waste; a general-purpose thickness;
• 50mm/75mm: Suitable for hard materials such as metal scraps, construction waste, and thick-walled pipes; strong impact resistance, not prone to deformation or cracking.
The blade installation structure directly affects the equipment's operational stability and subsequent downtime for maintenance. Modular shredder blades and hexagonal spindle blades are the preferred choices, representing the current optimal solution:
1. Modular structure: Adopts a three-stage design of "blade body + claw blade + auxiliary blade," eliminating the need to disassemble the entire shaft. Worn parts can be replaced simply by loosening and tightening bolts, reducing downtime by 80%, suitable for companies that require continuous operation;
2. Hexagonal spindle structure: Both the inner hole of the blade and the main shaft are hexagonal in design. Compared to traditional spline structures, torque transmission is more uniform, and the blade is not subjected to uneven stress, effectively preventing blade cracking and main shaft deformation. Suitable for low-speed, high-torque operating conditions;
3. Staggered arrangement design: The blades are arranged in a spiral staggered pattern on the blade shaft, ensuring that blades are always involved in shearing during rotation. This improves crushing efficiency and effectively prevents material jamming and clogging, and is a standard design for all high-quality blades.
When choosing dual-shaft shredder blades, don't just consider the initial performance, but also the long-term maintenance costs and reusability. An easy-to-sharpen and reusable blade can significantly reduce long-term consumable costs:
1. Prioritize sharpenable materials: Cold work tool steel (SKD-11, Cr12MoV) and H13 can be repeatedly sharpened, while high-manganese steel's performance decreases significantly after sharpening, so repeated sharpening is not recommended;
2. Pay attention to adjustable gap: High-quality blades support precise shredder blade gap adjustment. The gap between blades and between blades and liners can be calibrated according to the material and output requirements. Timely adjustment of excessive gaps can effectively ensure crushing efficiency and prevent material slippage.
When choosing dual-shaft shredder blades, it's easy to fall into three major misconceptions:
Misconception 1: Only considering hardness, not toughness. Blindly choosing high-hardness tool steel to process construction waste containing sand and gravel results in frequent chipping and cracking of the blades due to insufficient impact resistance;
Misconception 2: Pursuing low prices while neglecting material and manufacturing processes. Low-priced blades are often made of inferior steel with no proper heat treatment process, resulting in substandard hardness and edge wear after only a few days of use, thus increasing replacement costs;
Misconception 3: Using the same type of blade for all materials. Using 9CrSi blades to process metal scraps and high-manganese steel blades to process hard plastics will both lead to rapid blade failure and low equipment efficiency.
To correctly select double-shaft shredder blades, no complex calculations are needed; simply follow these three points:
1. Determine the material: Based on the material's hardness and impurity content, determine the blade material (high-manganese steel / 9CrSi / cold work die steel / special steel);
2. Determine the parameters: Select the number of claws based on the desired output particle size, select the thickness based on the material hardness, and select the installation structure (modular / hexagonal main shaft) based on the equipment model;
3. Determine maintenance: Prioritize blades that can be reground, have multiple cutting edges, and have adjustable gaps to improve reusability and reduce long-term operating costs.
Finally, a reminder: Double-shaft shredder blades are not standardized parts; customized selection is the optimal solution. When selecting blades, be sure to provide the supplier with detailed equipment parameters (model, shaft diameter, number of blades) and material information (type, hardness, impurity content, required output particle size) so that the manufacturer can customize them according to your needs. This will ensure that the blades match the equipment and working conditions, truly achieving improved efficiency, reduced costs, and stable operation of the machine.