Methods for adjusting the mesh size of a Raymond mill analyzer

　　The core method for adjusting the particle size(i.e.,powder fineness)of a Raymond mill classifier is achieved by adjusting the rotational speed of the classifier and the airflow of the control system.A higher classifier rotational speed results in greater centrifugal force,lower fine powder throughput,and a coarser finished product mesh size;conversely,a lower rotational speed results in a finer mesh size.Airflow adjustment is achieved by changing the blower power or valve opening.Increased airflow causes the material to be carried away quickly,resulting in a coarser mesh size;decreased airflow prolongs the grinding time,resulting in a finer mesh size.
　　This is a very specific and important operational issue.The classifier(or grader)of the Raymond mill(pendulum mill)is the core component controlling the fineness of the finished product."Adjusting the mesh size"essentially means adjusting the rotational speed of the classifier.
　　Adjustment Method(Steps and Key Points):

　　一.The following are standard and safe operating procedures:

　　1.Shutdown Preparation:
　　The main machine(grinding roller device)and feeder must be completely stopped.
　　Wait for the classifier and blower to idle for a few minutes to clean any residual powder from the pipes and grinding chamber.This is to ensure accurate comparison of fineness before and after adjustment and to prevent material accumulation.
　　2.Determine the Adjustment Target:
　　Clearly define the target fineness you need to adjust to(e.g.,from 200 mesh to 325 mesh).
　　3.Operate the Analyzer SpeedRegulator:
　　Core Operation:Operate the analyzer speed regulator located near the control cabinet or motor.Modern Raymond mills typically use frequency converter control;simply set or adjust the target frequency(Hz)on the frequency converter panel.Higher frequency increases speed,resulting in a finer finished product;lower frequency decreases speed,resulting in a coarser finished product.
　　Traditional Mechanical SpeedRegulation:Older equipment may use a mechanically speed-regulating motor or belt pulley speed change.This requires adjusting the gearbox gear or replacing the pulley via a handle to change the speed.
　　4.Synchronously Adjust the Fan Airflow:
　　Key Coordination:After adjusting the analyzer speed,the fan airflow must be adjusted accordingly(by adjusting the damper opening on the fan inlet pipe).Principle:When increasing the analyzer speed(for finer particles),the fan airflow should be increased appropriately to provide sufficient suction to carry away the fine powder and prevent qualified fine powder from falling back to the grinding disc for regrinding.Conversely,when decreasing the speed,the airflow can be reduced appropriately to prevent coarse powder from being drawn out.
　　Matching airflow and speed is key to obtaining ideal output and fineness,and requires fine-tuning according to actual conditions.
　　5.Restart and Verification:
　　After adjustment,start the equipment in the normal sequence:Fan→Analyzer→Main Unit→Feeder.
　　After the equipment has stabilized(approximately 15-30 minutes),take a sample for testing at the cyclone collector discharge port or packaging port.
　　Use a standard sieve or laser particle size analyzer to check if the finished product fineness meets the target.
　　If it does not meet the standard,repeat steps 3 and 4 for fine-tuning until it stabilizes and meets the requirements.

　　二.Adjustment Formula and Empirical Reference

　　While there is no absolutely precise universal formula,the general relationship between rotation speed and fineness is as follows:
　　Fineness(mesh size)∝Analyzer Rotation Speed
　　The rotation speed adjustment range is typically between tens of rpm and over two hundred rpm.For example,when grinding a 325-mesh product,the analyzer rotation speed may need to be around 200-300 rpm(the specific value varies depending on the equipment model,material density,and humidity).
　　A rule of thumb:For each increase in mesh size(e.g.,from 200 mesh to 250 mesh),the analyzer rotation speed needs to be increased by approximately 10-20 rpm,along with an increase in airflow.However,this is only a starting point and must be verified through sampling.

　　三.Precautions and Prohibitions

　　1.Never adjust the speed while the machine is running:Never adjust the analyzer rotation speed while the equipment is running,especially during the main grinding process,as this can easily lead to mechanical damage or personal injury.
　　2.Feed rate linkage:When increasing the fineness(increasing the rotation speed),the grinding resistance increases,and the output will decrease.Generally,the feed rate needs to be appropriately reduced to avoid excessive material accumulation in the grinding chamber and overloading of the main unit.Conversely,the feed rate can be appropriately increased when coarsening.
　　3.Influence of Material Properties:The density,viscosity,and moisture content of different materials have a significant impact on the classification effect.When changing materials,even if the mesh size is the same,it may be necessary to find the optimal speed-airflow combination again.
　　Equipment Status:Wear on the analyzer blades,loose fan belts,and air leaks in the pipelines can all affect classification accuracy.Ensure the equipment is in good condition before adjustment.
　　4.Gradual Adjustment:Avoid making large adjustments all at once.Adjustments should be made in small increments,and the system response(such as main unit current,fan negative pressure,etc.)should be observed.

　　Mesh size adjustment=analyzer speed adjustment+fan airflow adjustment+feed rate adjustment.
　　This is a closed-loop process of"setting-verification-fine-tuning,"requiring operators to make comprehensive judgments and optimizations based on equipment parameters,material characteristics,and test results.For the new Raymond mill with a high degree of automation,you only need to set the target fineness in the control system,and the PLC will automatically adjust the frequency of the frequency converter and the opening of the damper.However,understanding the underlying principle is crucial for troubleshooting and process optimization.