Ring Die Pelletizer Roller Replacement Tutorial: 6 Key Steps
Why is it necessary to replace rollers properly?
The roller is a core wear part of the ring die pelletizer. Long-term wear will lead to:
Decreased output: Increased gap between the roller and the ring die, insufficient extrusion force
Poor pellet formation: Rough surface, increased pulverization rate
Equipment damage: Uneven wear causes uneven wear of the ring die or vibration of the main shaft.
Preparation before replacement: Safety and tool list
Safety measures:
o Disconnect the main power supply and hang a “Do Not Power On” warning sign;
o Wait for the equipment to cool completely to prevent burns.
o Disconnect the main power supply and hang a “Do Not Power On” warning sign;
o Wait for the equipment to cool completely to prevent burns.
Tool preparation:
o Hydraulic puller, torque wrench, Allen wrench;
o Copper rod, wooden mallet (avoid directly striking steel parts);
o New roller skin, lubricant, cleaning agent.
o Hydraulic puller, torque wrench, Allen wrench;
o Copper rod, wooden mallet (avoid directly striking steel parts);
o New roller skin, lubricant, cleaning agent.
Detailed Explanation of 6 Key Steps
Step 1: Disassembling the Casing and Transmission Components
Remove the bolts from the pellet mill casing and lift it away from the protective cover;
Use a special tool to loosen the main shaft lock nut (note the thread direction, usually reverse thread).
Remove the bolts from the pellet mill casing and lift it away from the protective cover;
Use a special tool to loosen the main shaft lock nut (note the thread direction, usually reverse thread).
Step 2: Removing the Old Pressure Roller Assembly
Slowly push out the pressure roller shaft using a three-pronged jack, avoiding violent impact that could damage the bearing seat;
If the pressure roller is stuck, spray it with a penetrating agent and soak it for 10 minutes before proceeding.
Slowly push out the pressure roller shaft using a three-pronged jack, avoiding violent impact that could damage the bearing seat;
If the pressure roller is stuck, spray it with a penetrating agent and soak it for 10 minutes before proceeding.
Step 3: Separating the Pressure Roller Sheet from the Bearing.
The pressure roller sheet is fixed with an interference fit; use a three-pronged jack to vertically press out the old roller sheet.
Key Note: Retain the bearing housing support plate to prevent bearing deformation.
The pressure roller sheet is fixed with an interference fit; use a three-pronged jack to vertically press out the old roller sheet.
Key Note: Retain the bearing housing support plate to prevent bearing deformation.
Step 4: Cleaning and Inspection
Thoroughly remove residual dirt, lubricating oil, etc. from the journal and bearing housing with a cleaning agent;
Check for bearing damage; if the play is >0.5mm, replace it simultaneously.
Thoroughly remove residual dirt, lubricating oil, etc. from the journal and bearing housing with a cleaning agent;
Check for bearing damage; if the play is >0.5mm, replace it simultaneously.
Step 5: Install the new pressure roller skin
Heat the new pressure roller skin to 150℃(based on thermal expansion and contraction), and quickly press it into the bearing assembly;
After cooling, measure the outer diameter runout; it must be <0.1mm.
Heat the new pressure roller skin to 150℃(based on thermal expansion and contraction), and quickly press it into the bearing assembly;
After cooling, measure the outer diameter runout; it must be <0.1mm.
Step 6: Reset and Clearance Adjustment
Reinstall the pressure roller assembly back onto the main shaft and tighten the lock nut to the specified torque;
Adjust the clearance between the pressure roller and the ring die to 0.3-0.5mm (measured with a feeler gauge); there should be no friction noise when manually rotating the roller.
Reinstall the pressure roller assembly back onto the main shaft and tighten the lock nut to the specified torque;
Adjust the clearance between the pressure roller and the ring die to 0.3-0.5mm (measured with a feeler gauge); there should be no friction noise when manually rotating the roller.
Common Mistakes and Avoidance Methods
| Problems | Incorrect operation | Correct Method |
| Bearing damage | Directly hammering the pressure roller shaft | Use a hydraulic puller to evenly push out the ring die |
| Uneven clearance | Adjusting based on experience without using a feeler gauge | Measure four points at 360° angles to ensure consistent gaps |
| Roller wear | Failure to check the flatness of the ring die | Simultaneously check ring die wear when replacing the pressure roller |
Post-Replacement Testing and Acceptance Standards
1. No-Load Test Run:
* Jog the equipment and observe for any abnormal noises or vibrations;
* After no abnormal noises are detected, lubricate the assembly. The time should be set according to the machine model.
* Run for 10 minutes; bearing temperature rise < 40
℃.
* Jog the equipment and observe for any abnormal noises or vibrations;
* After no abnormal noises are detected, lubricate the assembly. The time should be set according to the machine model.
* Run for 10 minutes; bearing temperature rise < 40
℃.
2. Load Test:
* Use oil-containing material (such as rice bran) to lubricate the die holes during the initial feeding phase;
* Check if the pellet forming rate reaches 95% or higher and if the current fluctuation is stable.
* Use oil-containing material (such as rice bran) to lubricate the die holes during the initial feeding phase;
* Check if the pellet forming rate reaches 95% or higher and if the current fluctuation is stable.
Daily Recommendations for Extending the Life of the Pressure Roller
* Cleaning per Shift: Feed a small amount of oil-containing material before shutdown to reduce residual adhesion;
* Periodic Lubrication: Replenish with high-temperature grease every 200 hours of operation (grease injection should not exceed 60% of the cavity);
* Gap Inspection: Check the gap between the pressure roller and the ring die weekly with a feeler gauge and adjust promptly.
Conclusion
Standardized operation is the cornerstone of long-term equipment operation. Although pressure roller replacement is routine maintenance, details determine the results.
Users are advised to strictly follow the above steps and establish maintenance records to document the time of each replacement and the extent of wear. For technical support, our company can provide on-site guidance or remote video diagnostics.