How to Determine Whether a Screen Plate Needs Replacement

Observing the Screen Plate’s Appearance

1. Wear
   Carefully inspect the screen plate’s surface. If obvious signs of wear, such as localized thinning or perforations, are observed, this indicates that the plate’s structural integrity has been compromised. For example, during sand and gravel screening, frequent friction with the material gradually erodes the screen plate’s surface. If wear depth exceeds one-third of the original thickness, this is a cause for concern, as it could lead to plate cracking and compromise screening performance.
2. Deformation
   A normal screen plate should be flat. Deformation, such as bending or twisting, alters the shape and size of the screen openings, making material flow through the openings unstable. For example, in a vibrating screen, long-term high-frequency vibration can cause uneven stress on the screen plate, leading to deformation. If visible deformation of the sieve plate is observed, and the deformation exceeds 10% of the total sieve plate area, replacement should be considered.
3. Corrosion

Sieve plates are susceptible to corrosion if corrosive substances are present in the production environment. Corrosion can cause rust spots and pitting on the sieve plate surface. For example, in the chemical industry, sieve plates exposed to corrosive chemical solutions will gradually erode. If corrosion covers a large area (over 20%) of the sieve plate surface, or if the corrosion depth reaches a certain level that seriously affects the plate’s strength, the sieve plate must be replaced.

Checking Screening Performance

1. Screening Accuracy
   The primary function of a sieve plate is to screen materials to a specific particle size. If, under normal operating conditions, a large amount of material that does not meet the particle size requirements is present in the product, such as excessive coarse particles mixed with fine particles that should be screened out, or excessive fine particles remaining in coarse particles, this indicates that the sieve plate’s screening accuracy has deteriorated. For example, in flour production, if a high amount of unground wheat kernels appears in the finished flour, the sieve plate may be clogged or damaged, preventing accurate particle size separation and requiring replacement.
2. Screening Efficiency
   Observe the speed and volume of material passing through the sieve plate. If, under the same feed rate and operating conditions, the time it takes for material to pass through the sieve plate increases significantly, or the volume of material passing through the sieve plate per unit time decreases significantly, this indicates a decrease in screening efficiency. For example, in coal screening, if the machine previously processed 100 tons of coal per hour but now only processes 60 tons, and other equipment failure factors have been eliminated, the sieve plate is likely clogged or damaged, resulting in reduced screening efficiency. In this case, replacement of the sieve plate is necessary.

Pay attention to equipment operating conditions.

1. Abnormal Vibration
   For equipment that relies on vibration for screening, such as vibrating screens, problems with the sieve plate can cause abnormal vibration. For example, severe wear or deformation of a part of the sieve plate can cause uneven vibration and unusual noise during operation. Once operators notice a significant change in the frequency or amplitude of the equipment’s vibrations, and after eliminating other sources of vibration interference, it’s likely due to a problem with the screen plate. They should promptly inspect and determine whether the screen plate needs replacement.
2. Changes in Equipment Load
   Poor screen plate condition can affect the equipment’s load. When the screen plate becomes clogged, material passes more difficult, and the equipment must overcome greater resistance to operate, increasing the motor current. By monitoring equipment operating parameters such as motor current, if the current is consistently above normal levels and fluctuates significantly, after eliminating other factors such as motor failure, it’s likely that a problem with the screen plate is causing the increased equipment load. In this case, the screen plate should be inspected and evaluated for replacement.
   In summary, a comprehensive assessment, including observing the screen plate’s appearance, checking the screening performance, and monitoring the equipment’s operating status, can accurately determine whether the screen plate needs replacement, thereby ensuring efficient and stable production.