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EnglishViews: 0 Author: Site Editor Publish Time: 2026-07-27 Origin: Site
The metering rod, also called the coating rod and the coating metering rod, is a precision metering tool used in coating processes. It is widely employed in the production of coated paper, films, adhesive tapes, optical materials, and other products.
The metering rod is the core component in the coating process, enabling precise control of the coating fluid thickness on the substrate surface and achieving micron-level accuracy.
Typically, metering rods are mainly made of stainless steel. So the coating metering rods have excellent corrosion and wear resistance and are capable of withstanding the environments associated with various types of coating fluids.
If you want to further enhance the surface hardness and wear resistance of the metering rod and reduce friction, the surface can be chrome-plated.
The surface structure of the metering rod directly determines its coating performance. It can be broadly categorized into two types, smooth rods and grooved rods.
The surface of the smooth coating metering rod is free of grooves. It is primarily used for hydrodynamic metering, its diameter and surface finish are key factors influencing the coating weight of the metering rod.
The surface of the grooved coating rod is machined with continuous wavy grooves or wrapped with steel wire for volumetric metering.
The shape, depth, and width of the metering rod grooves directly determine the wet film thickness and are the key factors controlling coating precision.
Depending on the manufacturing process, the metering rod can be primarily categorized into two types, wire-wound and extrusion-type.
The wire-wound metering rod represents the most traditional manufacturing process for coating rods.
The manufacturing process of the wire-wound metering rod involves using a precision-ground stainless steel mandrel as the core and winding polished stainless steel wire around it at high speed.
The wire-wound coating metering rod forms grooves by winding steel wire of varying diameters. The diameter of the wire used determines the wet film thickness of the rod coating. Typically, the ratio of wire diameter to wet film thickness is 1:10.
Due to its simple structure and low manufacturing costs, the wire-wound metering rod is suitable for applications that require frequent changes in coating thickness. However, it poses a risk of wire breakage and loosening during coating.
The extrusion-type metering rod is manufactured using a cold extrusion process. Utilizing precision molds, continuous, uniform wavy grooves are extruded directly onto the surface of the stainless steel coating rod.
This manufacturing process avoids metering rod issues such as wire breakage or loosening associated with wire-winding methods. It offers superior precision and straightness, as well as a smooth, easy-to-clean surface, making it particularly suitable for coating processes with stringent cleanliness requirements.
To ensure the metering rod functions correctly and achieves its expected service life, regular inspection, maintenance, and care are required.
After the coating process, the metering rod must be removed and immediately cleaned with fresh water or a coating cleaning agent. Then, wipe the coating metering rod clean with a soft cotton cloth following the direction of the rod's texture, and apply a uniform coating of machine oil for protection. Finally, store it inside the telescopic tube.
When cleaning the metering surface, care should be taken not to scratch it. Avoid using bleach, detergents containing abrasives, steel wool, and abrasive tools to clean the coating metering rod.
Upon completion of the washing process, rinse the surface of the metering rod with clean water to remove the washing solution.
If there is dust or easily removable dirt on the surface of the metering rod, you can clean it with clear water or a mild soap-based detergent.
If binder residues adhere to the surface of the coating rod, it must be wiped clean using an organic solvent such as alcohol, ether, or benzene.
If the surface of the metering rod is contaminated with grease or lubricating oil, wipe it clean with a soft cloth. Then you should wash the coating rod with a neutral detergent, an ammonia solution, or a specialized cleaning agent.
If any bleaching agents or other strong acidic substances remain on the surface of the metering rod, it must be rinsed with water immediately.
Next, you need to saturate it with an ammonia solution or a dilute sodium carbonate solution, and finally wash it with a mild detergent or warm water.
If the rust is caused by surface contaminants on the metering rod, remove the contaminants and rust using a commercially available anti-rust paste, then clean the rod thoroughly with fresh water or a mild alkaline soapy solution.
