Views: 2 Author: Site Editor Publish Time: 2025-05-01 Origin: Site
The rotating blade is the most crucial and core component of the entire pelletizing process — it's the soul of underwater strand pelletizing.
Depending on the pelletizing process, rotating blades are generally made from two types of materials: one for underwater strand pelletizing and the other for dry cutting machines.
Underwater Strand Pelletizing
For basic materials like PET, PA, and PBT, the SL03 type rotating blade is commonly used. Its body is made of stainless steel, and the blade teeth are crafted from Stellite alloy through welding.
The SL05 type rotating bladefeatures a full outer layer of Stellite alloy teeth, created under high temperature and pressure around the entire blade body
Dry Cutting Machines
Materials are categorized into two types:
Non-reinforced materials: Typically use the WS rotating blade, made entirely of steel.
Reinforced materials (such as those with carbon black, glass fiber, or limestone powder): Require the HM type rotating blade, made of tungsten steel.
HM blades are divided into two types:
G-blade: Welded inserts.
F-blade: Inserted blade pieces, offering higher strength compared to G-blades.
Both types are fixed onto the blade head.
1. Types of Tooth Profiles
Key parameters for tooth profiles include:
FW/Rear Angle: The angle between the back of the blade and the parallel direction.
BW/Front Angle: The angle between the cutting edge and the vertical direction.
FB/Back Width: The width of the blade back.
RF/Back Edge Width: The width of the tough edge at the back.
T/Tooth Depth: The vertical distance from the blade tip to the blade base.
Main Tooth Types:
Type 8 Blade:
Used for elastomers, which are softer materials. The sharper, steeper teeth are ideal for cutting soft elastomers.
Type 2 Blade:
Used for PET, a harder and more brittle material. These blades have a wider back to improve cutting durability.
Type 10 Blade:
Used for nylon, which is softer and tougher. Requires a smaller back width and a sharper edge for optimal cutting.
2. Lifespan Analysis of Pelletizer Rotating Blades
There are both incorrect and correct sharpening practices:
Common Sharpening Mistakes:
1.Only sharpening the blade back: This excessively reduces the blade's outer diameter, shortening its service life.
2.Only sharpening the blade tip: Alters the tooth angle, excessively widens the back, compresses pellets, and causes irregular shapes and faster wear.
3.Improper external sharpening: Alters both front and rear angles, making the blade unusable.
Correct Practice:
For the first sharpening of a new blade, a full tooth profile grinding should be performed to maximize usage and minimize outer diameter loss.
3. Maintenance and Sharpening of Rotating Blades
During sharpening, the grinding wheel cuts the rotating blade at high speed on a specialized machine, generating high heat — so cooling fluid is essential for temperature control.
To enhance blade sharpening quality — achieving minimal material removal and maximum blade durability — the full tooth profile grinding method is recommended, preserving:
Front Angle: Between the tooth edge and the vertical.
Rear Angle: Between the blade back and the horizontal.
Ideal Cutting Condition:
When the fixed blade and rotating blade edges meet at 90°, pellet production is optimal. Therefore, maintaining original angles during each sharpening is critical.
Additional Tip:
Each time the blade is resharpened, the tooth depth should be slightly deepened. A deeper tooth slot stores more pellets, reduces clogging, and enhances production efficiency.
Shallow slots may trap pellets, damaging the blade and lowering productivity.
Surface Finish:
Full profile grinding also smooths out previous wear marks, giving the blade a refreshed look while maintaining superior quality — a perfect combination of functionality and aesthetics.
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