Slotted Screen Basket Components and Quality Inspection

Pressure screen and their accessories, including screen basket, have always been crucial to paper making and pulping. With the continuous advancement of pulp screening technology, screen baskets have become widely used in paper making and pulping. To ensure the quality of screen baskets, strict control is required throughout the entire manufacturing process.

The components of a slotted screen baskets‍ are: bars, center drum ring, upper flange, and lower flange.

The slot width of a slotted screen basket refers to the minimum distance between two adjacent bars. The cross sectional shape and quality of the bars directly affect the size and uniformity of the slotted screen basket, and thus the pulp screening performance. Slotted screen basket bars are typically 3 to 4 meters long. They are then cut into different sizes based on the height of the screen drum and cleaned for assembly.

Slotted Screen Basket Bar Quality

Currently, slotted screen basket bar materials include 316L, 321, and 304, with 316L being the highest quality. During testing, a magnet can be used to test the bar to confirm whether it is mixed. During the test, you can use a magnet to test the bar to confirm whether the bar are mixed.

The cross sectional dimensions of the bar is randomly inspected, and detailed records and data are analyzed. The average of the measured data is used as the dimensional benchmark for the batch of bar. The measured bar is marked to ensure that the rods match the groove width and spacing on the corresponding screen drum ring. If the cross-sectional dimensions exceed the allowable range, the bar should be rejected.

Inspect the bar type and length according to the screen basket model and bar cross section requirements. Visually inspect the bar for straightness. Avoid dead bends or cross sectional distortion. Keep the bar as straight as possible to avoid affecting the final assembly result. Degrease and clean the bar to ensure a smooth surface. Once dry, place bar from the same screen basket together and clearly label them for easy assembly.

Regarding the Quality of the Upper and Lower Flanges and Center Ring of the Slotted Screen Basket

The blanks for the upper and lower flanges of the slotted screen baskets are mostly forged, while the center ring is typically rolled and then welded. To reduce internal stress during the forging, rolling, and welding processes, the blanks should be annealed. Flanges are generally outsourced for processing. In addition to testing the material, the dimensions of the flanges should also be checked according to the drawing requirements to ensure an appropriate machining allowance for subsequent machining. The welding quality of the flange and the middle drum ring should meet the welding technical requirements. The ring surface should be flat, and the overall warpage should not exceed the allowable value, otherwise it will affect the quality of subsequent assembly. After annealing, the flanges and rings should be stored according to regulations and clearly labeled.

To mount the bars on the center drum hoop (sometimes the bars can also be mounted on the upper and lower flanges), the center drum hoop (or the center drum and upper and lower flanges) must be grooved. The center drum hoop should generally be sandblasted or polished before grooving.

Before grooving, the cutting pattern should be inspected according to the drawing requirements and the actual bar conditions. Only after passing the inspection can grooving begin. During the grooving process, test checks should be performed using matching rods to correct cutting errors and prevent mistakes. The size and spacing of the grooves should meet the seam width requirements of the screen basket being processed. The grooves should be consistent, the graduations should be uniform, and the cut surface should be smooth. After cutting, the workpieces should be cleaned, stored neatly, and clearly labeled for assembly.